820-00281 No PPDC_IN

Ryanlen2

Member
Board has no signs of liquid damage. Came in with dead battery and no power. When I plug in adapter I get .4## Volts on PPDCIN_G3H. Also QB400 gets very hot and after about 30 seconds the charger cuts off.
I only have the center portion of a donor for this board as I could not find the right side on ALI. I did however order FDPC4044's from mouser and new ISL's as well in hopes that those would be the issue. After replacing QB400 I still get basically nothing on PPDCIN_GH and QB400 is scorching hot.
I have zero experience with this board and to be honest am a bit intimidated, LOL. Here is what I get on he power meter. ------------> https://photos.app.goo.gl/fmqazwSWFTkddYmk9

Any help is appreciated. Thanks!
 

2informaticos

Administrator
Staff member
Post resistance to ground on R7020 and F7000.

Don't wait again 30s when you already detect overhrating.
In fact, never power up a board before check for shorts...
 

JohnB8812

New member
Resistance to ground on PP3v3_G3H and DC in? Seems like you have a short causing the fet to get hot possibly a CD3215
 

2informaticos

Administrator
Staff member
Don't think to start with 20V.
Always start with low voltage, no matters nominal voltage of the rail.
If you start with 1V, increase voltage maintaining ampers bellow current limit of the bench power supply.
 

JohnB8812

New member
Yeah I'd say start low around 3-4 volts then work your way up. For me, the DC in shorts usually are found at 5 volts so 20 is probably not necessary.
 

Ryanlen2

Member
trying to inject 3.5V on DCIN line. Here are 2 pics. One is with PSU set for voltage injection at 3.5 and the other is while attempting injection. Amperage goes up to 3.9 and board will only take .7 V.

https://photos.app.goo.gl/FwDpj7zjCVdMZLRB7

I did not force by raising the amps/voltage once I saw that the board wasn't taking it.

Is this a secondary short? What should I do?

Thanks for the help. Have a good one!
 
Last edited:
Top