hello, �� i have been sitting on some microsoft surface pro 4 tablets for a while now. i was originally tasked with replacing the battery in one of the tablets, and ended breaking the screen and logic board in the process. decided to buy another tablet with the same specs. got that screen off successfully of the second tablet. the logic board appeared good, but i guess i shorted something out in the installation process of the logic which i've read is a common issue if there is no barrier between the logic board and battery pins. all that said, i ate costs of the repair and have been sitting on the tablets ever since. i have since ordered the ITE chip that supposedly fixes the issues with the no power after battery replace. however, on one of the tablets i have when i connect the charge cable / ac adapter into the charge port of the tablet i do not see the charge light. whereas with the other tablet i do so see the charge light. i have swapped the charge port connectors that attach the logic board of the tablets and still do no see the LED illuminate on the second logic board, thus ruling out the charge port connector as fault for the no LED charge light
i then downloaded the brd files for this tablet and the schematic (thank you �� very much badcaps forum).
i have never successfully used a schematic / brd view file to fix a component level fault on a logic board before, and i've read these tablets are an awful place to start to try and fix faults at a component level, however these are the devices i'm working with so giving it the ol college attempt.
i've read several threads on this forum related to no power issues with these tablets, and often i see mentions of follow the power sequence for the device, and for my case (the tablet with no light on the LED of the charge cable) this is what i have recorded so far.
BTW, the logic board for the tablets are the exact same, ie. x910540-007
1. using my multimeter i read ~= 11.7V on PD5503 both side
2. read ~= 11.6V on PQ5505 pin 2
3. read ~= 3.6V on PQ5506 pin 2
4. read ~= 11.6V on U5605 pin 6
4a. read 0V on pin 4 of the U5505 (which i believe should have ~= 3V)
on the tablet that shows the charge light i read ~= 2.8V on pin 4 of the U5505
i took all those voltages with the stock power connector connected to the tablet as i do not have a variable voltage power supply on hand. (just hobbyist here).
after reading those voltage levels on the tablet with the no LED power cable is it safe to think that the fault / reason for the LED on the power cable not lighting up is U5505? or is that suppose to be getting the ~= 3V from somewhere else that could possibly be the fault?
forgive me for my soliloquy, i just figure providing more information is better than providing not enough in the spirit of troubleshooting.
i then downloaded the brd files for this tablet and the schematic (thank you �� very much badcaps forum).
i have never successfully used a schematic / brd view file to fix a component level fault on a logic board before, and i've read these tablets are an awful place to start to try and fix faults at a component level, however these are the devices i'm working with so giving it the ol college attempt.
i've read several threads on this forum related to no power issues with these tablets, and often i see mentions of follow the power sequence for the device, and for my case (the tablet with no light on the LED of the charge cable) this is what i have recorded so far.
BTW, the logic board for the tablets are the exact same, ie. x910540-007
1. using my multimeter i read ~= 11.7V on PD5503 both side
2. read ~= 11.6V on PQ5505 pin 2
3. read ~= 3.6V on PQ5506 pin 2
4. read ~= 11.6V on U5605 pin 6
4a. read 0V on pin 4 of the U5505 (which i believe should have ~= 3V)
on the tablet that shows the charge light i read ~= 2.8V on pin 4 of the U5505
i took all those voltages with the stock power connector connected to the tablet as i do not have a variable voltage power supply on hand. (just hobbyist here).
after reading those voltage levels on the tablet with the no LED power cable is it safe to think that the fault / reason for the LED on the power cable not lighting up is U5505? or is that suppose to be getting the ~= 3V from somewhere else that could possibly be the fault?
forgive me for my soliloquy, i just figure providing more information is better than providing not enough in the spirit of troubleshooting.
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