Nexus 7 2013, USB port (almost) dead

Nexus 7 2013, USB port (almost) dead - Nexus 7 (2013) Q&A

Updated my Flo to the latest versions of Unlegacy Android, TWRP and Magisk a while ago. Afterwards, it wouldn't charge. The USB settings behaved somewhat flaky too, so decided to go back to the earlier versions. Still wouldn't work. Noticed at that point that it wouldn't charge in TWRP either (it should, right?). Decided to try to flash the latest stock rom to rule out any software problems. Put the Flo in bootloader mode, where Fastboot wouldn't find it, no matter which USB port and cables I tried. Tried to reflash the bootloader instead, should rule out any software related problems too.
I've loaded up USBTreeview on the computer to monitor USB activity, and tried plugging the Flo in different USB modes. Nothing happens at all, the USB port seems completely dead.
Also opened the Flo up, stripped a USB Micro cable, and tested for continuity between the wire ends and points after the connector on the PCB. The connector turned out to be ok.
The strange thing is that it charges just fine if I turn it off completely. Assuming it has something to do with everything that could control the charging circuitry being turned off.
So, anyone got any ideas at all what to try next? I'm out of them myself.

.kaputnik. said:
....stripped a USB Micro cable, and tested for continuity between the wire ends and points after the connector on the PCB. The connector turned out to be ok....
Click to expand...
Click to collapse
If you refer to the daughterboard PCB then it is inconclusive. Continuity between the port and the motherboard PCB needs to be verified. The wide, silver cable between the PCBs is often problematic. The connections are....
A - 1 (+5V)
B - 3 (data)
C - 2 (data)
D - 4 (OTG)
E - 5 (GND)

k23m said:
If you refer to the daughterboard PCB then it is inconclusive. Continuity between the port and the motherboard PCB needs to be verified. The wide, silver cable between the PCBs is often problematic. The connections are....
A - 1 (+5V)
B - 3 (data)
C - 2 (data)
D - 4 (OTG)
E - 5 (GND)
Click to expand...
Click to collapse
Thanks for the suggestion
Checked the connections as per above, had continuity between all testpoints. The silvery FFC and its connectors seems to be fine.
Also pulled and reseated the FFC in both ends, just in case temporary contact was made somewhere when I removed and flipped the motherboard over to access the test points. No change though, the USB port is still dead
Edit: you don't happen to know what the 4 pin surface mount IC on the data traces close to the USB connector is? Two diodes integrated on an IC perhaps?

.kaputnik. said:
Thanks for the suggestion
Checked the connections as per above, had continuity between all testpoints. The silvery FFC and its connectors seems to be fine.
Also pulled and reseated the FFC in both ends, just in case temporary contact was made somewhere when I removed and flipped the motherboard over to access the test points. No change though, the USB port is still dead
Edit: you don't happen to know what the 4 pin surface mount IC on the data traces close to the USB connector is? Two diodes integrated on an IC perhaps?
Click to expand...
Click to collapse
I checked N7's USB port....
Unit off, charger disconnected, ohmmeter measures:
GND-5V: 8kohm
GND-D1: 3Mohm
GND-D2: 3Mohm
D1-D2: 8Mohm
(meter polarity makes no difference)
Unit on, Android running, voltmeter measures:
GND-5V: 0V
GND-D1: 0V
GND-D2: 0VCan you please verify the above?
You did test a few USB modes, but there is one, very low-level from the SoC itself, you have not tried:
- turn it off and disconnect USB
- press both vol buttons and...
- plug in to a PC
Now your PC should register a new USB\VID_05C6&PID_9008 device [in QHSUSB_DLOAD mode]
Yes, the IC is an ESD suppressor. It may even absorb the hit from a faulty charger and protect the tablet from destruction by excessive power supply...
:highfive:

k23m said:
I checked N7's USB port....
Unit off, charger disconnected, ohmmeter measures:
GND-5V: 8kohm
GND-D1: 3Mohm
GND-D2: 3Mohm
D1-D2: 8Mohm
(meter polarity makes no difference)
Unit on, Android running, voltmeter measures:
GND-5V: 0V
GND-D1: 0V
GND-D2: 0VCan you please verify the above?
You did test a few USB modes, but there is one, very low-level from the SoC itself, you have not tried:
- turn it off and disconnect USB
- press both vol buttons and...
- plug in to a PC
Now your PC should register a new USB\VID_05C6&PID_9008 device [in QHSUSB_DLOAD mode]
Yes, the IC is an ESD suppressor. It may even absorb the hit from a faulty charger and protect the tablet from destruction by excessive power supply...
:highfive:
Click to expand...
Click to collapse
You're absolutely right, had no idea about QHSUSB_DLOAD mode. It works, there's hope, the hardware might be okay after all! Odd though, imagined the bootloader USB code was quite low level and standalone too, but maybe it shares libs with the rest of the system or something?
The connection details from USBTreeview, if it's of any use. Looks just fine to me at least, P/C 28 is of course just the missing driver:
Code:
=========================== USB Port1 ===========================
Connection Status : 0x01 (Device is connected)
Port Chain : 1-1-1
Properties : 0x01
IsUserConnectable : yes
PortIsDebugCapable : no
PortHasMultiCompanions : no
PortConnectorIsTypeC : no
======================== USB Device ========================
DriverKeyName : ERROR_FILE_NOT_FOUND
+++++++++++++++++ Device Information ++++++++++++++++++
Device Description : QHSUSB_DLOAD
Device ID : USB\VID_05C6&PID_9008\6&3A6A7FD9&0&1
Hardware IDs : USB\VID_05C6&PID_9008&REV_0000 USB\VID_05C6&PID_9008
Driver KeyName : -
Legacy BusType : PNPBus
Enumerator : USB
Location Info : Port_#0001.Hub_#0004
Location IDs : PCIROOT(0)#PCI(1A00)#USBROOT(0)#USB(1)#USB(1), ACPI(_SB_)#ACPI(PCI0)#ACPI(USBE)#ACPI(RHUB)#ACPI(PRT1)#USB(1)
Container ID : {acbd03bb-d39a-11e9-844a-f46d044eca1c}
Manufacturer Info : -
Capabilities : 0x04 (Removable)
Status : 0x01806400 (DN_HAS_PROBLEM, DN_DISABLEABLE, DN_REMOVABLE, DN_NT_ENUMERATOR, DN_NT_DRIVER)
Problem Code : 28 (CM_PROB_FAILED_INSTALL)
Power State : D3 (supported: D0, D2, D3, wake from D0, wake from D2)
+++++++++++++++++ Registry USB Flags +++++++++++++++++
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\usbflags\05C690080000
osvc : REG_BINARY 00 00
SkipContainerIdQuery : REG_BINARY 01 00 00 00
---------------- Connection Information ---------------
Connection Index : 0x01 (1)
Connection Status : 0x01 (DeviceConnected)
Current Config Value : 0x00
Device Address : 0x02 (2)
Is Hub : 0x00 (no)
Device Bus Speed : 0x02 (High-Speed)
Number Of Open Pipes : 0x00 (0 pipes to data endpoints)
Data (HexDump) : 01 00 00 00 12 01 00 02 00 00 00 40 C6 05 08 90 [email protected]
00 00 01 02 00 01 00 02 00 02 00 00 00 00 00 01 ................
00 00 00 ...
--------------- Connection Information V2 -------------
Connection Index : 0x01 (1)
Length : 0x10 (16 bytes)
SupportedUsbProtocols : 0x03
Usb110 : 1 (yes)
Usb200 : 1 (yes)
Usb300 : 0 (no)
ReservedMBZ : 0x00
Flags : 0x00
DevIsOpAtSsOrHigher : 0 (Is not operating at SuperSpeed or higher)
DevIsSsCapOrHigher : 0 (Is not SuperSpeed capable or higher)
DevIsOpAtSsPlusOrHigher : 0 (Is not operating at SuperSpeedPlus or higher)
DevIsSsPlusCapOrHigher : 0 (Is not SuperSpeedPlus capable or higher)
ReservedMBZ : 0x00
Data (HexDump) : 01 00 00 00 10 00 00 00 03 00 00 00 00 00 00 00 ................
---------------------- Device Descriptor ----------------------
bLength : 0x12 (18 bytes)
bDescriptorType : 0x01 (Device Descriptor)
bcdUSB : 0x200 (USB Version 2.00)
bDeviceClass : 0x00 (defined by the interface descriptors)
bDeviceSubClass : 0x00
bDeviceProtocol : 0x00
bMaxPacketSize0 : 0x40 (64 bytes)
idVendor : 0x05C6 (Qualcomm, Inc)
idProduct : 0x9008
bcdDevice : 0x0000
iManufacturer : 0x01 (String Descriptor 1)
iProduct : 0x02 (String Descriptor 2)
iSerialNumber : 0x00 (No String Descriptor)
bNumConfigurations : 0x01 (1 Configuration)
Data (HexDump) : 12 01 00 02 00 00 00 40 C6 05 08 90 00 00 01 02 [email protected]
00 01 ..
------------------ Configuration Descriptor -------------------
bLength : 0x09 (9 bytes)
bDescriptorType : 0x02 (Configuration Descriptor)
wTotalLength : 0x0020 (32 bytes)
bNumInterfaces : 0x01 (1 Interface)
bConfigurationValue : 0x01 (Configuration 1)
iConfiguration : 0x00 (No String Descriptor)
bmAttributes : 0x80
D7: Reserved, set 1 : 0x01
D6: Self Powered : 0x00 (no)
D5: Remote Wakeup : 0x00 (no)
D4..0: Reserved, set 0 : 0x00
MaxPower : 0x01 (2 mA)
Data (HexDump) : 09 02 20 00 01 01 00 80 01 09 04 00 00 02 FF FF .. .............
FF 00 07 05 81 02 00 02 00 07 05 01 02 00 02 00 ................
---------------- Interface Descriptor -----------------
bLength : 0x09 (9 bytes)
bDescriptorType : 0x04 (Interface Descriptor)
bInterfaceNumber : 0x00
bAlternateSetting : 0x00
bNumEndpoints : 0x02 (2 Endpoints)
bInterfaceClass : 0xFF (Vendor Specific)
bInterfaceSubClass : 0xFF
bInterfaceProtocol : 0xFF
iInterface : 0x00 (No String Descriptor)
Data (HexDump) : 09 04 00 00 02 FF FF FF 00 .........
----------------- Endpoint Descriptor -----------------
bLength : 0x07 (7 bytes)
bDescriptorType : 0x05 (Endpoint Descriptor)
bEndpointAddress : 0x81 (Direction=IN EndpointID=1)
bmAttributes : 0x02 (TransferType=Bulk)
wMaxPacketSize : 0x0200 (max 512 bytes)
bInterval : 0x00 (never NAKs)
Data (HexDump) : 07 05 81 02 00 02 00 .......
----------------- Endpoint Descriptor -----------------
bLength : 0x07 (7 bytes)
bDescriptorType : 0x05 (Endpoint Descriptor)
bEndpointAddress : 0x01 (Direction=OUT EndpointID=1)
bmAttributes : 0x02 (TransferType=Bulk)
wMaxPacketSize : 0x0200 (max 512 bytes)
bInterval : 0x00 (never NAKs)
Data (HexDump) : 07 05 01 02 00 02 00 .......
----------------- Device Qualifier Descriptor -----------------
Error : ERROR_GEN_FAILURE
-------------------- String Descriptors -------------------
String descriptors are not available (because the device has problem code CM_PROB_FAILED_INSTALL)
Didn't think any measurements were needed now when I got the QHSUSB_DLOAD mode working, but did them anyways since you asked me to. Now I'm really confused. Strangely enough, some of my measurements are very different from yours, and meter polarity seems to matter here. Perhaps my meter uses a higher voltage than yours, higher than the ESD suppressor forward voltage, or something? Still hard to explain the differences with Android running though...
Plugged in and measured through the USB Micro cable I cut and stripped before:
Unit off, charger disconnected, battery still connected:
GND-5V: 7.8kOhm (polarity independent)
GND-D-: 18.5 kOhm (-probe on GND) 4.1 kOhm (+probe on GND)
GND-D+: >40 MOhm (-probe on GND) 9.3 MOhm (+probe on GND)
D+-D-: 9.3 MOhm (+probe on D-), >40MOhm (-probe on D-)
Unit on, Android running:
GND-5V: 5.2VDC
GND-D1: 0V
GND-D2: 0.31VDC
Redid the measurements twice with the same results.
As you probably have noticed, I'm very much a novice in this field. Got no idea what the voltages and resistances are supposed to be. Is it possible it could be something with the charging circuitry? Another thought, there's [only?] 209 kOhm between the mode select pin and ground. Is it perhaps possible that my device is stuck in OTG mode?
Ah, it's some kind of zener barrier. Thought it might be for signal processing only first, but hard to determine by measurements when you're not sure it's not broken
Once again, thanks a lot for your time and effort in helping me out with this. I really appreciate it. Even if we don't find a solution, it's at least very interesting and educative

.kaputnik. said:
.....Perhaps my meter uses a higher voltage than yours
....Still hard to explain the differences with Android running though...
Plugged in and measured through the USB Micro cable I cut and stripped before:
Unit off, charger disconnected, battery still connected:
GND-5V: 7.8kOhm (polarity independent)
GND-D-: 18.5 kOhm (-probe on GND) 4.1 kOhm (+probe on GND)
GND-D+: >40 MOhm (-probe on GND) 9.3 MOhm (+probe on GND)
D+-D-: 9.3 MOhm (+probe on D-), >40MOhm (-probe on D-)
Unit on, Android running:
GND-5V: 5.2VDC
GND-D1: 0V
GND-D2: 0.31VDC
.....there's [only?] 209 kOhm between the mode select pin and ground. Is it perhaps possible that my device is stuck in OTG mode?
....Even if we don't find a solution, it's at least very interesting and educative
Click to expand...
Click to collapse
Your ohmmeter is different but we should see comparable results from the more consistent diode-test:
Unit off, charger disconnected, diode-test measures:
GND-5V: 2.6V; 0.5V reverse
GND-D1: 1.2V; 0.7V reverse
GND-D2: 1.2V; 0.7V reverse
D1-D2: 1.5V; 1.5V reverse
GND-ID: 0.8V; 0.8V reverseAs for the differences in Android, it seems that your micro cable is from an OTG adaptor and has pins 4 and 5 shorted, hence you get this 5V out and also active data. Please disconnect it and check the ID pin on diode-test.
Let's see the hardware logs. Please 'install' the attached file in TWRP within 3 minutes from initial reboot. Then find 'logs.tgz' in the root of internal storage and attach it here or upload somewhere and post a link.
This case is very interesting indeed, cheers! :good:

k23m said:
Your ohmmeter is different but we should see comparable results from the more consistent diode-test:
Unit off, charger disconnected, diode-test measures:
GND-5V: 2.6V; 0.5V reverse
GND-D1: 1.2V; 0.7V reverse
GND-D2: 1.2V; 0.7V reverse
D1-D2: 1.5V; 1.5V reverse
GND-ID: 0.8V; 0.8V reverseAs for the differences in Android, it seems that your micro cable is from an OTG adaptor and has pins 4 and 5 shorted, hence you get this 5V out and also active data. Please disconnect it and check the ID pin on diode-test.
Let's see the hardware logs. Please 'install' the attached file in TWRP within 3 minutes from initial reboot. Then find 'logs.tgz' in the root of internal storage and attach it here or upload somewhere and post a link.
This case is very interesting indeed, cheers! :good:
Click to expand...
Click to collapse
Ah, good idea
Unit off, charger disconnected, diode-test measures:
GND-5V: 2.3V; 0.5V reverse
GND-D1: 0.9V: 0.6V reverse
GND-D2: 0.9V; 0.6V reverse
D1-D2: 1.3V; 1.3V reverse
GND-ID: 0.8V; 0.7V reverse.
Did all measurements both with and without the cable, just to see if the cable introduced any effects. The results were identical.
A little lower across the block, but generally much more consistent with your readouts
As for the differences in Android, it seems that your micro cable is from an OTG adaptor and has pins 4 and 5 shorted
Click to expand...
Click to collapse
Well, if it was from an OTG cable, the GND-ID resistance would have been somewhere close to 0 ohm rather than the 209 kOhm I got yesterday Re-measured GND-ID just in case, without the cable, directly on the connector pins. Still 209 kOhm.
If you'd like, I could double check by measuring the 5VDC-GND voltage with the device powered again, directly on the connector pins, without the cable. Would rather not though, it's far too easy to slip with the probes and short something out.
Ran the system log collector twice. Booted to TWRP and ran the collector as quickly as I could, booted the system and downloaded/deleted the logs from the device, rebooted to TWRP again, and let it sit for 2 mins before running it a second time, to really give everything time to initialize properly.
Had to zip the logs, the forum wouldn't let me attach .tgz files. Hope you can find anything out. Had a look in the logs myself, and quickly established that this is way over my head, you really need to know what to look for for those to be of any use

.kaputnik. said:
...Well, if it was from an OTG cable, the GND-ID resistance would have been somewhere close to 0 ohm rather than the 209 kOhm I got yesterday Re-measured GND-ID just in case, without the cable, directly on the connector pins. Still 209 kOhm. ....
Click to expand...
Click to collapse
So, if not the cable, then we have an internal issue - your N7 is stuck in OTG mode. This mode is ignored by the low-level QHSUSB_DLOAD and only then PC can detect it or CHARGE IT when off! (except for modified Android kernels which enable charging in OTG mode)
No doubt about it, compare the logs....
Code:
your dmesg
<7>[ 2.876586] id_pin_irq_work_function: gpio_get_value(APQ_OTG_ID_PIN) = 0
<6>[ 2.876586] id_pin_irq_work_function: APQ_OTG_ID_PIN is low : Host mode
dmesg in normal mode
<7>[ 2.077331] id_pin_irq_work_function: gpio_get_value(APQ_OTG_ID_PIN) = 1
Final check - unit on, Android running, USB disconnected (non-OTG mode):
USB pins 5-4, voltmeter measures... GND-ID: 1.8VIf you measure below 1.8V, it is confirmed, and we will search for a remedy next... :fingers-crossed:

k23m said:
So, if not the cable, then we have an internal issue - your N7 is stuck in OTG mode. This mode is ignored by the low-level QHSUSB_DLOAD and only then PC can detect it or CHARGE IT when off! (except for modified Android kernels which enable charging in OTG mode)
No doubt about it, compare the logs....
Code:
your dmesg
<7>[ 2.876586] id_pin_irq_work_function: gpio_get_value(APQ_OTG_ID_PIN) = 0
<6>[ 2.876586] id_pin_irq_work_function: APQ_OTG_ID_PIN is low : Host mode
dmesg in normal mode
<7>[ 2.077331] id_pin_irq_work_function: gpio_get_value(APQ_OTG_ID_PIN) = 1
Final check - unit on, Android running, USB disconnected (non-OTG mode):
USB pins 5-4, voltmeter measures... GND-ID: 1.8VIf you measure below 1.8V, it is confirmed, and we will search for a remedy next... :fingers-crossed:
Click to expand...
Click to collapse
Confirmed, the GND-ID voltage with Android running and USB disconnected is only 347 mV.
Powered the device off again, and did some resistance measurements while at it. As mentioned before, the GND-ID resistance is 209 kOhm (or 0.8V with diode test). Disconnected the silvery FFC in the USB daughterboard end, GND-ID resistance jumped to > 40 MOhm. Reconnected the FFC and disconnected it in the motherboard end instead, still > 40 MOhm. That should rule out any issues with the FFC and USB daughterboard at least. Diode test with the FFC disconnected gives, 3.07V, max probing voltage of my multimeter (getting the same reading with probes in the air).
Did a quick checkup of the motherboard with a strong flashlight and a loupe. Nothing obvious visible to the eye, like burned components/PCB, signs of water ingress, [conductive] debris, etc. Leaving the motherboard removed by the way, in case there's something specific you want me to check.
If you feel like opening your N7 again, as a reference, what is your GND-ID resistance reading (powered off, USB disconnected) ?
From your second post in the thread, it looks like you have access to schematics etc. Googled around some, but could only find this kind of documentation for the 2012 model. You don't happen to have a link? Would probably be incredibly helpful with pin designation tables for the FFC connectors, etc, if available
This is getting really interesting now by the way
Edit: Judging by the log, it looks like the the OTG mode is controlled by a GPIO "pin" being pulled high or low. Guessing the circuitry leading up to the GPIO interface is quite simple. If the problem is something with the circuitry, rather than with the GPIO interface itself, I'm no stranger to desoldering components, cutting traces, etc and completely disable OTG mode. I'm never gonna use it. The N7 is just a "secondary device" nowadays, mostly used for watching movies, HMI for the ODB interface in the car, and cyberloafing on the toilet
Edit 2: Took a second closer look at the motherboard, and this time I found something when focusing on the components! What looks like an inductor to me, at the power supply management chip, is busted. Even found the chipped off fragment in the case. See attached photos.
Could definitely explain why that GPIO pin isn't high enough. Doubting I've caused that when removing the mobo, been very careful with it.

.kaputnik. said:
Disconnected the silvery FFC in the USB daughterboard end, GND-ID resistance jumped to > 40 MOhm
what is your GND-ID resistance reading (powered off, USB disconnected) ?
it looks like you have access to schematics
looks like an inductor to me, at the power supply management chip, is busted. Even found the chipped off fragment in the case.
Click to expand...
Click to collapse
OK, the daughterboard is not faulty. I measure 300kohm GND-ID resistance. No worries about the ferrite bit from the inductor.
I don't have the schematics and they would not help much in this multi-layer, compact PCB, BGA design. It seems that there is a conductive leak from the pin to GND caused by corrosion, or internal IC voltage pull-up resistor failure. So, let's try a simple mod to correct this situation. Please solder a 100kohm resistor between +5V and the ID - the area around USB port is most convenient for it. If the resistor is not enough to increase ID to 1.8V, then try 10k next. If still not enough, use 1k, but not any lower values.
Should this mod be unsuccessful, you can always use Timur's kernel which enables charging in OTG mode. :victory:
:highfive:

k23m said:
OK, the daughterboard is not faulty. I measure 300kohm GND-ID resistance. No worries about the ferrite bit from the inductor.
I don't have the schematics and they would not help much in this multi-layer, compact PCB, BGA design. It seems that there is a conductive leak from the pin to GND caused by corrosion, or internal IC voltage pull-up resistor failure. So, let's try a simple mod to correct this situation. Please solder a 100kohm resistor between +5V and the ID - the area around USB port is most convenient for it. If the resistor is not enough to increase ID to 1.8V, then try 10k next. If still not enough, use 1k, but not any lower values.
Should this mod be unsuccessful, you can always use Timur's kernel which enables charging in OTG mode. :victory:
:highfive:
Click to expand...
Click to collapse
Got no means of measuring inductance, but a resistance comparison to the other inductors in the same area, which looks identical, suggests the coil is ok at least. Assuming those are only for filtering out high frequency ripple, shouldn't matter if the inductance is a little bit off. So, no worries
Will try the mod once I'm a little less shaky, was out for a few beers yesterday night Had the same general idea yesterday, but waited in case you had a more elegant solution
Really hoping it'll work, would be nice to have fastboot access etc.
Edit: you don't happen to have a suggestion of a point to tap 5VDC from, that's powered when the device is not in OTG mode, btw? Hard for me to find one with a device stuck in OTG

.kaputnik. said:
....you don't happen to have a suggestion of a point to tap 5VDC from, that's powered when the device is not in OTG mode, btw? Hard for me to find one with a device stuck in OTG
Click to expand...
Click to collapse
Sure, I propose either the 4V or precise 3.0V. This ~4V comes almost directly from unregulated battery (via a MOSFET only) and needs to be handled carefully. If you prefer a safer option, but hard to reach tap, go for the 3.0V. Also, the shielded area of ELAN IC, the touch control chip, could be explored for more regulated voltage options. Personally I'd use 4V as it is right next to the ID test point near USB port.
:fingers-crossed:

k23m said:
Sure, I propose either the 4V or precise 3.0V. This ~4V comes almost directly from unregulated battery (via a MOSFET only) and needs to be handled carefully. If you prefer a safer option, but hard to reach tap, go for the 3.0V. Also, the shielded area of ELAN IC, the touch control chip, could be explored for more regulated voltage options. Personally I'd use 4V as it is right next to the ID test point near USB port.
:fingers-crossed:
Click to expand...
Click to collapse
So, tested with a 100 kOhm between the 4V point and ID yesterday morning, but it wasn't enough. The ID-GND voltage landed lower than I expected. Had some social stuff going on for the rest of the day, and also today, so had to put it aside until now.
Decided to do it experimentally instead, so soldered a couple of salvaged DIP socket pins to wire pieces, connected them to the 4V and ID test points, and started working through my resistor assortment downwards. At 8k2 charging started to work. The ID-GND voltage was still far from 1.8V though, more like 1.2V or something like that, but hell, it worked, was happy enough with that
Soldered in a 6k7 resistor to have some margin, and put the device back together again. Now it's happily charging. Will try fastboot mode etc later on, but I believe we can assume the mission is accomplished
I'm extremely impressed by your incredible patience and pedagogic, thorough way of putting things, leaving nothing out! If you ever get any technical problems with your > 30000 ton merchant ship, I'll gladly help you in return; that's my field of expertise, and probably the only place where I possibly could measure up to your help with this
Once again, thanks a lot!
Edit: a couple of pics from the modding, if you're interested:

.kaputnik. said:
So, tested with a 100 kOhm between the 4V point and ID yesterday morning, but it wasn't enough. The ID-GND voltage landed lower than I expected. Had some social stuff going on for the rest of the day, and also today, so had to put it aside until now.
Decided to do it experimentally instead, so soldered a couple of salvaged DIP socket pins to wire pieces, connected them to the 4V and ID test points, and started working through my resistor assortment downwards. At 8k2 charging started to work. The ID-GND voltage was still far from 1.8V though, more like 1.2V or something like that, but hell, it worked, was happy enough with that
Soldered in a 6k7 resistor to have some margin, and put the device back together again. Now it's happily charging. Will try fastboot mode etc later on, but I believe we can assume the mission is accomplished
I'm extremely impressed by your incredible patience and pedagogic, thorough way of putting things, leaving nothing out! If you ever get any technical problems with your > 30000 ton merchant ship, I'll gladly help you in return; that's my field of expertise, and probably the only place where I possibly could measure up to your help with this
Once again, thanks a lot!
Edit: a couple of pics from the modding, if you're interested:
Click to expand...
Click to collapse
Great news! Every fixed Nexus 7'13 makes me very happy :victory:
I wish we had its service manual with complete schematic diagrams and could diagnose more problems with better efficiency. It is a 6 year old tech and I hope that the schematics will eventually leak out on the internet.
Note to future readers - the 4V track goes right down to USB port area and if you scratch the paint, you could solder a small SMD resistor there without any wires. Thanks to kaputnik's experiments we now know it should be around 6.7k-4.7k.
Cheers :highfive:

Related

[Q] Charging Range

What's the charging range for the Xperia Arc?
The outlet wall plug output is 5V DC 850mA
I'm thinking about getting a external battery, though it's output is 1A-2A.
(TeckNet iEP390 Power Station)
Will this harm my phone, or will it charge my phone faster than the wall outlet?

May caused a very large heat due to ammount of power which not used, where it can go, then in HEAT...
Use max 1A or anything belove it.
Above 1A can be risky and critical for phone, chargher, cabel or anything else.
Sent from my LT15i using XDA Premium

Any chance you know the charging range when connected to a pc?

PC gives to you 5V.

At what ampere?

that depends on charger and wire resistant.
I - Electric
U - 5v
R - resistor
I= U/R
I= 5:1 = 5A
I= 5/2 = 2.5A
I= 5/3 = 1.66A
I= 5/4 = 1.25A
I= 5/5 = 1A
ETC

The normal limit for a USB port on a computer is 500mA.
USB "chargers" can provide more (typically 850mA) and will charge the phone faster. However, as someone else pointed out, a proper USB PC port and/or charger will regulate the voltage to no more than 5.25V, which given the laws of electricity limits the current that can be drawn for charging. It is actually the phone that controls the charging, assuming a properly regulated input power. An unregulated battery would not be a good charging source.
The micro-USB connector is itself rated to a maximum of 1.5A.

Investigating the charging operations of the 5X

Since the Google engineer Benson Leung is reviewing some USB Type-C to Type-A/B adapters and bringing the proper USB spec to our attention, I decided to investigate some of the things related to charging in the Nexus 5X.
Related posts:
http://forum.xda-developers.com/nexus-5x/accessories/google-engineer-reviewing-usb-type-c-t3241104
https://plus.google.com/+BensonLeung/posts/LH4PPgVrKVN
https://plus.google.com/+BensonLeung/posts/3Xf724K84HP
Here is the relevant dmesg of me plugging in an out-of-spec (10kΩ pullup) cable:
Code:
[59722.367419] __qpnpint_handle_irq: 1 triggered [0x2, 0x13,0x0] usbin-uv
[59722.542304] fusb301 5-0021: fusb301_work_handler: int_sts[0x05]
[59722.542899] fusb301 5-0021: sts[0x2f], type[0x08]
[59722.542909] fusb301 5-0021: fusb301_src_detected: FUSB_STATE_ATTACHED_SNK
[59723.370779] msm-dwc3 f9200000.ssusb: DWC3 exited from low power mode
[59723.513914] dwc3 f9200000.dwc3: Avail curr from USB = 3000
[59723.724676] android_work: android_work: sent uevent USB_STATE=CONNECTED
[59723.729421] android_work: android_work: sent uevent USB_STATE=DISCONNECTED
[59723.834497] android_work: android_work: sent uevent USB_STATE=CONNECTED
[59723.846230] android_usb gadget: high-speed config #1: fe80f0c8.android_usb
[59723.902145] android_work: android_work: sent uevent USB_STATE=CONFIGURED
Note the line that writes "Avail curr from USB = 3000". This line indicates that the USB controller detected the 10k pullup in the connector and configured the maximum available current is 3000mA (aka 3A).
On the lock screen, it says "charging rapidly".
In this case, `/sys/class/power_supply/usb/voltage_now` shows `4609780`, which indicates that the USB voltage detected on the device end is about 4.6V, which is 0.4V lower than 5V.. So, even though it is pulling 3A and luckily didn't fry the USB 3.0 port of my laptop, it probably won't charge as fast as the LG charger due to the huge voltage drop..
---
Here is the relevant dmesg of me plugging in another out-of-spec (10kΩ pullup) cable (which is noticeably thinner than the one before):
Code:
[59656.433560] __qpnpint_handle_irq: 1 triggered [0x2, 0x13,0x0] usbin-uv
[59656.644386] fusb301 5-0021: fusb301_work_handler: int_sts[0x05]
[59656.645294] fusb301 5-0021: sts[0x1f], type[0x08]
[59656.645313] fusb301 5-0021: fusb301_src_detected: FUSB_STATE_ATTACHED_SNK
[59657.426205] msm-dwc3 f9200000.ssusb: DWC3 exited from low power mode
[59657.573627] dwc3 f9200000.dwc3: Avail curr from USB = 3000
[59657.784381] android_work: android_work: sent uevent USB_STATE=CONNECTED
[59657.788909] android_work: android_work: sent uevent USB_STATE=DISCONNECTED
[59657.853872] SMBCHG: smbchg_update_input_max: update iusb = 500
[59657.895507] android_work: android_work: sent uevent USB_STATE=CONNECTED
[59657.907950] android_usb gadget: high-speed config #1: fe80f0c8.android_usb
[59657.962062] android_work: android_work: sent uevent USB_STATE=CONFIGURED
Now, this might seem similar to the previous one.
But notice the additional line "SMBCHG: smbchg_update_input_max: update iusb = 500". What does it mean? The lock screen also shows "charging slowly" at the same time.
Searching `smbchg_update_input_max` didn't yield any results.
Looking at the sysfs, I found this interesting entry `/sys/module/qpnp_smbcharger/parameters/smbchg_ibat_ocp_threshold_ua` which has the value `4500000`.
It appears to me that the driver `qpnp-smbcharger` is detecting the USB voltage, and if the voltage is below 4.5V it automatically changes the maximum USB input current to 500mA in order to keep the USB voltage within range. This slows down the charging by quite a lot, but at the same time it prevents the USB port/charger/battery pack from becoming a flaming toaster.
Relevant kernel source code: https://android.googlesource.com/ke...allow-dr/drivers/power/qpnp-smbcharger.c#3093
I am thinking that it may be possible to limit the USB input current (to 0.5 or 1.5A) by software, so that even if the USB cable is out of spec and doesn't follow the correct pullup arrangement, it can be used to charge the phone safely without exceeding the safe current limits.
How do you think?

Your theory sounds promising... I wonder if there is already code on the phone to do something similar? DO we have a documented case of a Nexus frying a charger yet? I know all of Benson's work to date has been with a Pixel which has a much higher demand for power as well as more restrictive requirements allowing a charge. Benson mentioned that he will soon be getting a Nexus to test with.

I know this is a total n00b question but I leave my phone plugged in most of the time when I'm at home--is this in any way bad for the battery?

Hey does anyone know why when I select charging sound on in the settings, there is no sound when charging the phone?

minnemike said:
Your theory sounds promising... I wonder if there is already code on the phone to do something similar? DO we have a documented case of a Nexus frying a charger yet? I know all of Benson's work to date has been with a Pixel which has a much higher demand for power as well as more restrictive requirements allowing a charge. Benson mentioned that he will soon be getting a Nexus to test with.
Click to expand...
Click to collapse
I think I've seen a few post about it frying car chargers before. I am not really bothered enough to look it up though.
In theory it can absolutely happen for chargers of low quality or those lacking protection circuits (read: cheap Chinese ones). In reality though, the voltage drop may already be enough to cause the phone to switch to 500mA max. charging current.
Regarding the code, I am not sure if there are any exposed sysfs interfaces or ioctl's that would allow setting the charging current directly. But it is pretty obvious that there is already code inside the kernel that can set it, just perhaps not controllable within userspace. It wouldn't be really difficult for someone to add a sysfs interface in custom kernels though.

Does anyone know if we're safe with any cable when N5X shows only charging slowly?
I would think N5X shows charging slowly when it requests current of 500mA so it shouldn't damage the charger no matter how old it is.
Is my assumption correct?

LR07 said:
Hey does anyone know why when I select charging sound on in the settings, there is no sound when charging the phone?
Click to expand...
Click to collapse
I have this setting configured as well and it does nothing, but this is perhaps better suited for another thread.

BinkXDA said:
I have this setting configured as well and it does nothing, but this is perhaps better suited for another thread.
Click to expand...
Click to collapse
I actually think that the sound is to notify you when your phone is low on battery. You know when your phone is a 15% it alerts you?

LR07 said:
I actually think that the sound is to notify you when your phone is low on battery. You know when your phone is a 15% it alerts you?
Click to expand...
Click to collapse
I turned off the setting and when my phone got to 15% it still made the alert sound. So maybe there should be a sound when charging your phone

Please help - burned USB port on MTCC

Hi,
I bought a USB camera for my head unit (MTCC-KLD6-V2.91) from AliExpress, connected it (using a USB port which gets the power from the car, while the data gets into the head unit), and got a picture . After few seconds, it suddenly disappeared, so i did what i thought was wise - and tried the a different USB port (which gets the power directly from the head unit), but no still picture (i said - ohh well, cheap camera)
Trying to understand if that's a camera or a headunit issue, i tried to connect it to my PC, which happily was more sophisticated than the head unit, and notified me that the USB port is trying to consume too much power and got disconnected, well - that's a bummer! try to connect it again through a USB current meter - and it was shut down immediately - turns out the USB connector was defective, and when bent, was shortening the power lines.
I cut it out - replaced the connector, and got the camera to work (on my PC), but i wasn't so lucky with the head unit or the power adapter connected to the car, both aren't working anymore (the head unit works well - only the USB port isn't)
So I opened the head unit (hoping to see some burned fuse) - but no visible damage
Does anyone have an idea where/what to look for?
[ I'm not sure if the forum rules allows me to post link to the product i bought - but if anyone interested, message me and i'll be happy to share the link]
Thanks.

Burned USB
Hello, could you switch ON your WiFi interface on this headunit? Please send me a link to your headunit type. Maybe i can help you. BR Radek

ZelenyR said:
Hello, could you switch ON your WiFi interface on this headunit? Please send me a link to your headunit type. Maybe i can help you. BR Radek
Click to expand...
Click to collapse
i'm not sure i follow...
the device works well, everything but the USB port seems to not be affected by the shortage (so yes - i can turn on the wifi interface).
my device is :
MCU version：
MTCC-KLD6-V2.91
May 31 2016 19:54:14
Android version：
5.1.1
1024*600
Kernel version：
3.0.101+
[email protected] #11
Thu Jun 30 11:25:16 CST 2016
Build number：
rk3188-userdebug 22062016.17:05:11

burned USB
One day before I repaired one headunit with same issue and also reason of defect was same - high current from 5V supply on USB interface . Repaired MTCC has also another symptom and it was WiFi issue - when I tried to switch on WiFi interface system after few seconds switched it OFF. The reason is very simple - on that MTCC was supply of WiFi module connected to same 5V as USB ports.
5V on your mainboard will be probably generated by switching supply source and its current capability is bigger than 4A but this supply voltage is distributed to many subsystems and each trunk is switched by MOSFET. In my case weak point was inductor connected between 5V power supply and switching MOSFET. This inductor was burned by overcurrent . I think that in your case it will be similar. It is necessary to find path on PCB between supply source and +5V USB pin and on this path will be probably burned inductor. All is highly dependent on type of used mainboard.
BR Radek

Attached is an annotated image of my Klyde main board labeled KD-HCT-MB 2015/07/18 Rev-3.1 1535. The two switching regs on the right are controlled by the MCU; the upper one (U25) supplies the USB hub through transistors (Q8 & Q9) which are controlled by MCU pin 38. On my board there is an inductor (L14) near the USB device (U11) which supplies power to it. If you have a similar main board, that may be your inductor.

Burned USB
Hello, this is exactly picture of my repaired PCB. Inductor close to USB is used for separating path used for supply WiFi module ( there is 3.3V LDO supplied after MOSFET switch from this path close to WiFi). I don´t remember exact number of inductor but in my case was burned L16 ??? which is located on your PCB in group of components is on left side of the MCU under video switch, in middle of line of component above two electrolytic capacitors. This inductor is connected directly to 5V switching supply on one side and on oposite side is connected switching MOSFET which provides supply to USB ports (here is connected other inductor close the big black multiconnector).
BR Radek

ZelenyR said:
Hello, this is exactly picture of my repaired PCB. Inductor close to USB is used for separating path used for supply WiFi module ( there is 3.3V LDO supplied after MOSFET switch from this path close to WiFi). I don´t remember exact number of inductor but in my case was burned L16 ??? which is located on your PCB in group of components is on left side of the MCU under video switch, in middle of line of component above two electrolytic capacitors. This inductor is connected directly to 5V switching supply on one side and on oposite side is connected switching MOSFET which provides supply to USB ports (here is connected other inductor close the big black multiconnector).
BR Radek
Click to expand...
Click to collapse
Yes that group also includes the Q8 and Q9 I mentioned.

my device is :
MCU version：
MTCC-KLD6-V2.97
Android version：
5.1.1
1024*600
Kernel version：
3.0.101+
it is completely happened the same to me. When I did install my head unit it did have a smoke came out from my head unit look like something burned inside which look like burn by over current and then my wifi cannot work.
But can i ask how can test which compontent is broken and even i find out how can i replace it.
Look like the all the compontent is surface mount.
Thanks a lot.

Help!!! USB short circuit - USB and WiFi not working!
Hi
I have a similar issue. When cabling my car with a USB cable connected to my MTCB head unit I accidentally created a short circuit. I could see - and smell - the smoke.
The USBs and the WiFi are NOT working now. Everything else still works.
There is no signal at VCC pins in the USB ports and the WiFi is not working, so I presume the issue can be similar to what @ZelenyR and @dhmsjs described.
My board is a KGL-A90-MAIN-v06.1 - slightly different from @dhmsjs 's one.
I am posting the links to two pictures I just took - (sorry, the system won't let me attach them or add a link)
- Pic #1 (imageshack.com/a/img922/9544/VQeiqx.jpg). It shows the whole board, as a reference
- Pic #2 (imageshack.com/a/img924/4956/pfTsmB.png). It double-clicks into what I understand as the potentially faulty groups according to the info in this thread. I can't see any clear evidence of a burnt component; I can however notice some possible damage signs in the MOSFET (A79TF) (in yellow in the picture, look at that form of a 'bubble' in the middle of the component), but I am not entirely sure the component is damaged. The inductors L10 and L19 show continuity when measuring their resistance as well.
I would start replacing the MOSFET and - possibly - the inductors. Could you please help me:
(1) What type of SMD inductors do I need to use?
(2) Any idea looking at my board?
Many thanks!

santibiotico said:
...I can't see any clear evidence of a burnt component; I can however notice some possible damage signs in the MOSFET (A79TF) (in yellow in the picture, look at that form of a 'bubble' in the middle of the component), but I am not entirely sure the component is damaged. The inductors L10 and L19 show continuity when measuring their resistance as well.
I would start replacing the MOSFET and - possibly - the inductors. Could you please help me:
(1) What type of SMD inductors do I need to use?
(2) Any idea looking at my board?
Many thanks!
Click to expand...
Click to collapse
Given that the lnductors show continuity they are probably okay; I wouldn't try to replace them. Yes the MOSFET may likely be blown, especially if it has a "bubble" on it. That's what I would replace first.

Finally got to try and fix my unit
after trying all kind of 'external' fixes (such as getting USB to work by connecting an external 12v to 5v converter - which was faulty and caused my canbus decoder to always get 12v on the ignition wire - and yes, i tried to pull 12v from the canbus decoder ignition wire), i decided it's time to try and fix it in the right way.
i followed your advice - and found a path to the USB Vcc wire from the 7805 regulator, and i was kind of surprised - i have 5v (well, almost, 4.8) on the USB output, I connected some USB device - and the voltage dropped to 1.3v.
i narrowed it down to some component before the USB output, which has 5v on on end, and 4.8v on the other end, when i connect a USB device - the voltage on the 5v end stays 5v, but dropped to 1.3 on the other end - so i guess, eureka?
Now i just need to understand what is this component - where to get a replacement one and how to replace it (see attached image)
can you help identifying the component?
Thanks.

mrtowel said:
...can you help identifying the component?
Click to expand...
Click to collapse
Your board is different from mine, but very similar. On my board that component is labeled "L2" I think, although the printing is very poor so I can't be sure.
If yours is labeled L-something, then it is most certainly an inductor. They should normally have a very low resistance (a few ohms at most) and from the behavior you describe it sounds like this one has a fairly high resistance. So an easy check to confirm that would be to measure the resistance of the part with an ohmmeter. A high resistance would confirm that it is damaged.
As for replacement, I suspect that this is another case of a noise filter -- its purpose is to block electrical noise from the outside world from coming into the unit. But the only way to know for sure would be to draw out the whole circuit from 7805 to the USB port.
If it is just a noise filter then its value is probably not critical (any value of inductance is better than none), and for a test at least, you could just try jumpering across it. If that jumper gives you a solid 5v on the USB output, then that would also confirm that the inductor is the cause of your problem.
Make sure that the device you use to test the USB does not use much power! For instance your camera is probably not a good choice for testing.

dhmsjs said:
Your board is different from mine, but very similar. On my board that component is labeled "L2" I think, although the printing is very poor so I can't be sure.
If yours is labeled L-something, then it is most certainly an inductor. They should normally have a very low resistance (a few ohms at most) and from the behavior you describe it sounds like this one has a fairly high resistance. So an easy check to confirm that would be to measure the resistance of the part with an ohmmeter. A high resistance would confirm that it is damaged.
As for replacement, I suspect that this is another case of a noise filter -- its purpose is to block electrical noise from the outside world from coming into the unit. But the only way to know for sure would be to draw out the whole circuit from 7805 to the USB port.
If it is just a noise filter then its value is probably not critical (any value of inductance is better than none), and for a test at least, you could just try jumpering across it. If that jumper gives you a solid 5v on the USB output, then that would also confirm that the inductor is the cause of your problem.
Make sure that the device you use to test the USB does not use much power! For instance your camera is probably not a good choice for testing.
Click to expand...
Click to collapse
Eureka indeed, i soldered a jumper instead of the faulted inductor, and everything seems to work
do you think i better solder a replacement? or i'm all good with a simple jumper?

mrtowel said:
Eureka indeed, i soldered a jumper instead of the faulted inductor, and everything seems to work
do you think i better solder a replacement? or i'm all good with a simple jumper?
Click to expand...
Click to collapse
Congrats! The designers put that inductor there for a reason (why add the cost otherwise?) so a jumper is probably not the best solution. But if it works for you, that's what matters most. It's your choice which way to go.

dhmsjs said:
Congrats! The designers put that inductor there for a reason (why add the cost otherwise?) so a jumper is probably not the best solution. But if it works for you, that's what matters most. It's your choice which way to go.
Click to expand...
Click to collapse
I'm sure it's there for a reason, i'm just wondering what's the expected impact by not having that? less resilient to "noisy" USB devices? for me it actually protected the rest of the circuit from the over current.
if i'd like to replace it, what should i get? there is no indication of what exactly the value of it (in whatever unit inductors are measured)

mrtowel said:
I'm sure it's there for a reason, i'm just wondering what's the expected impact by not having that? less resilient to "noisy" USB devices? for me it actually protected the rest of the circuit from the over current.
if i'd like to replace it, what should i get? there is no indication of what exactly the value of it (in whatever unit inductors are measured)
Click to expand...
Click to collapse
Not USB devices so much as noise from the car's electrical system (spark plugs for example). Automotive environments are notoriously bad places for electronics to live in happily.
The units of inductance are "henries" or in this case microhenries. No way to tell the value now and I don't have a suitable meter so I can't measure mine. But again the value probably isn't critical, and any inductance is better than none. If you do want to replace it a good first order approximation might be to find one that is physically the same size. Pick one that's toward the upper end of the inductance range available for that physical size and you'll likely be fine.

Thank you so much... I fixed my wifi issue
Hi Guys, I've been reading this thread and fixed the wifi of my head unit MTCC-KLD6-V2.86... Like all here, all of sudden the wifi wouldnt switch on... After opening the unit and examining the main board, the L19 inductor was burnt (charcoaled ). As my electronic skills are very basic, I did what someone did here - to jumper the failed inductor and Voila!!! the wifi is back on working. I know there's a risk with this and simplest solution is not to use the USB cable that comes with the unit. I am happy with accessing internet via wifi/hotspot.. Hope this helps someone out there.
https://drive.google.com/open?id=0BzVz3275lE4aN3RNUGlpTE5rZVlXWmowckhGbHRtbm5PNGhz[/URL]
https://drive.google.com/open?id=0BzVz3275lE4aNmFZQWx0ZVB1NkxiT2cxZ0V3SUVUaFRBLVNj[/URL]
---------- Post added at 07:54 AM ---------- Previous post was at 07:49 AM ----------
mbchaves said:
Hi Guys, I've been reading this thread and fixed the wifi of my head unit MTCC-KLD6-V2.86... Like all here, all of sudden the wifi wouldnt switch on... After opening the unit and examining the main board, the L19 inductor was burnt (charcoaled ). As my electronic skills are very basic, I did what someone did here - to jumper the failed inductor and Voila!!! the wifi is back on working. I know there's a risk with this and simplest solution is not to use the USB cable that comes with the unit. I am happy with accessing internet via wifi/hotspot.. Hope this helps someone out there.
"https://drive.google.com/file/d/0BzVz3275lE4aN3RNUGlpTE5rZVlXWmowckhGbHRtbm5PNGhz/view"
Click to expand...
Click to collapse

Good info here

dhmsjs said:
Attached is an annotated image of my Klyde main board labeled KD-HCT-MB 2015/07/18 Rev-3.1 1535. The two switching regs on the right are controlled by the MCU; the upper one (U25) supplies the USB hub through transistors (Q8 & Q9) which are controlled by MCU pin 38. On my board there is an inductor (L14) near the USB device (U11) which supplies power to it. If you have a similar main board, that may be your inductor.
Click to expand...
Click to collapse
dhmsjs said:
Attached is an annotated image of my Klyde main board labeled KD-HCT-MB 2015/07/18 Rev-3.1 1535. The two switching regs on the right are controlled by the MCU; the upper one (U25) supplies the USB hub through transistors (Q8 & Q9) which are controlled by MCU pin 38. On my board there is an inductor (L14) near the USB device (U11) which supplies power to it. If you have a similar main board, that may be your inductor.
Click to expand...
Click to collapse
Hello. Sorry I reply here but I have got very similar main board as yours. I lost USB and wifi. What do you think what can be reason of that? Can you help me? I took off inductor L14. Can be that? Thank you and sorry

If you "took off" the inductor then yes that would disable the USB. In this situation the correct thing to do to "remove" the inductor from the circuit is to jumper across it. But why did you want to "take off" the inductor? Was it damaged? If the answer is yes, then you want to jumper across it, not remove it from the board.

Can Charge but Can't do any form of data transfer - USB help?

I thought I was lucking out when I got a 32GB Nexus 7 with a qi charger, decent condtion and cases for 40 bucks. USB port fried? easy fix.
I get the part 5 days late, and install it. I even install a new battery out of love! charging works but I never cared about that. I just want to unlock the bootloader but I can't because none of my computers will see it. windows 10 can't see it, linux can't see it, my mac can't see it. No response. But it charges. I've checked the white cable, reseated everything, no change.
what do I do? I'm really about to consider this a waste of 80 dollars and just return it or sell it online.

Galaxyninja66 said:
I thought I was lucking out when I got a 32GB Nexus 7 with a qi charger, decent condtion and cases for 40 bucks. USB port fried? easy fix.
I get the part 5 days late, and install it. I even install a new battery out of love! charging works but I never cared about that. I just want to unlock the bootloader but I can't because none of my computers will see it. windows 10 can't see it, linux can't see it, my mac can't see it. No response. But it charges. I've checked the white cable, reseated everything, no change.
what do I do? I'm really about to consider this a waste of 80 dollars and just return it or sell it online.
Click to expand...
Click to collapse
Can you confirm...
#1 N7 in fastboot mode, PC connected, on Linux command lsusb outputs among others:
Code:
Bus 001 Device 005: ID 18d1:4ee0 Google Inc.
#2 USB port external measurements (pic att):
Unit off, charger disconnected, ohmmeter measures:
GND-D1: 3Mohm
GND-D2: 3Mohm
D1-D2: 8Mohm
(meter polarity makes no difference)
Unit off, charger disconnected, diode-test measures:
GND-D1: 1.2V; 0.7V reverse
GND-D2: 1.2V; 0.7V reverse
D1-D2: 1.5V; 1.5V reverse

lsusb isn't showing any change, neither is dmesg.
I don't have the tool shown to get those kinds of measurements.
The person who sold me it has agreed to send me another one.

Question P6P not charging on PC USB port (random)

I do now own a dedicated P6 charger and usually end up charging my phone on the USB port of my PC during my workday.
I've noticed that occasionally the phone is simply not charging when connected to PC USB. Easy to verify with: 'adb shell dumpsys battery', e.g.:
Code:
Current Battery Service state:
AC powered: true
USB powered: false
Wireless powered: false
Max charging current: 1500000
Max charging voltage: 5000000
Charge counter: 2774000
status: 2
health: 2
present: true
level: 54
scale: 100
voltage: 3958
temperature: 238
technology: Li-ion
Then, after rebooting the phone, unplugging the USB cable, replugging it again, it starts charging again.
I have not found a way to reliably replicate the problem so I don't really know exactly when or why it happens.
I know that the USB port itself is fine. It works and my wife's phone consistenty charges fine on that port.
Anybody else having the same issue? I'll report it to Google ...

Did you try changing the PC USB port? And are you using a USB-C port?
A Pixel 6 Pro phone wants USB PD 3.0 PPS for charging, anything less than that and chances are that the phone will automatically shut down charging (on it's own) - Google says to prevent damage, I say to sell chargers. But the baseline is the same, it won't work reliably, or not at all.
On top of that comes the problem that Windows/ USB ports just suck. I have 4 front panel USB ports... and three of them don't like ADB, if I try to flash firmware from them on my phone, it will stuck/create bugs. If I use the fourth (middle right)... it will work without problems. Of course there is no other scenario on planet earth where the other USB ports ever caused me issues. That's tech just being non-compatible cr*p for no reason.

Morgrain said:
Did you try changing the PC USB port? And are you using a USB-C port?
A Pixel 6 Pro phone wants USB PD 3.0 PPS for charging, anything less than that and chances are that the phone will automatically shut down charging (on it's own) - Google says to prevent damage, I say to sell chargers. But the baseline is the same, it won't work reliably, or not at all.
On top of that comes the problem that Windows/ USB ports just suck. I have 4 front panel USB ports... and three of them don't like ADB, if I try to flash firmware from them on my phone, it will stuck/create bugs. If I use the fourth (middle right)... it will work without problems. Of course there is no other scenario on planet earth where the other USB ports ever caused me issues. That's tech just being non-compatible cr*p for no reason.
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I don't think its really a matter of USB PD/PPS. I think your second part, how much USB ports (and cables) can vary, is more likely. On new(ish) PCs or Laptops, USB ports are much better than they were 10-15 years ago. I can charge my Pro using many types of USB 2.0/3.0 Ports - PCs from 2009, laptops from 2010/2019, recent or older adapters (not PD/PPS etc). (repair laptops on the side so I have a stack of them). So the capability is there on the phone, so I'm leaning towards a USB Cable/USB port issue. And yes, the amperage the phone takes in can vary but if your cable, port and phone are working fine, the power should be consistent (always best to take in at least 700 mAh so the phone can charge, albeit at a slow and decent rate). just make sure you're using a quality usb cable ( I didn't believe in this much until I had an issue with fastboot/adb not working, new cable fixed it).
And for sure, USB ports on the front of PC's are notoriously horrible. So many different hardware, firmware, OS drivers (Linux can be problematic sometimes unfortunately) these types that vary so much (especially for USB-A - power, motherboard etc). Best to use the rear ports for consistency or a good powered USB hub plugged into the back.
The main benefit to PPS is the way it "steps" the voltage up or down, which is a benefit for fast chargers - but not really much benefit for charging using a USB port or adapters with lower amperage. But that's not to say that everything is all good, maybe because PPS is so new it might be causing issues on some Pixels, and the bugs need to be ironed out, I can't say for sure.
OP, are you using the original cable that came with your phone (usb-c port?)
- edit-- ok I see your comment, let us know

Alekos said:
OP, are you using the original cable that came with your phone (usb-c port?)
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Trying this now as we speak ;-)
Thanks for the tip.
See my previous reply to @Morgrain, getting a higher charging current on USB-C port and phone is indeed charging faster than on the USB-A port.

I built a new PC a year ago and it has to USB-C ports (one on the back, one via adapter cable to the motherboard - both I made easy access on the front of the computer case). I, too, have noticed that USB-C charges great (either OEM or an off-brand freebie but quality USB-C cable) through either USB-C port. Technically it's fast charging but it's nowhere near modern fast charging, so I'm not too worried about it.
I did try a USB-A port once and found it was charging too slowly to make sense, so I quickly abandoned it and have only used the USB-C ports and cables since when I'm working on the computer.
When I'm charging from my couch's or my bedroom surge protector's USB-A ports, the phone charges normally.

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