HP G7-1000 series R22 mobo problem

[bicalov]

Hi Folks,

Need some help, please.

I have a G7-1000 mobo with AMD cpu that won'nt turn on.
Replaced U3 already, since this is often the cause by these boards. no luck.
I don't get the +VIN. Till PQ38 pin 4 19,6V is present and pin 1 and pin 3 are 0V.
When I detach pin 3 from the board, pin 1 becomes 25,6V and pin 3 = 19,6 V.
I don't measure a short on the island from pin 3, but 36,8 Ohm all the way further down the line on all the components.

Can somebody point me in the right direction? I need some advise how to look at this.

[cyberhack]

Re: HP G7-1000 series R22 mobo problem

PQ38 could be faulty, under load breaking down.

[bicalov]

Re: HP G7-1000 series R22 mobo problem

PQ38 could be faulty, under load breaking down.

Thanks, I will try.

[meritosari]

Re: HP G7-1000 series R22 mobo problem

Hi Folks,

Need some help, please.

I have a G7-1000 mobo with AMD cpu that won'nt turn on.
Replaced U3 already, since this is often the cause by these boards. no luck.
I don't get the +VIN. Till PQ38 pin 4 19,6V is present and pin 1 and pin 3 are 0V.
When I detach pin 3 from the board, pin 1 becomes 25,6V and pin 3 = 19,6 V.
I don't measure a short on the island from pin 3, but 36,8 Ohm all the way further down the line on all the components.

Can somebody point me in the right direction? I need some advise how to look at this.

36,8 ohm....its seem look like shorted. 19v rails must be higher than that.
if laptop can't power on, then first thing you do is make sure 19v have no short (+vad, vin, +B, vbat, pvbat)
second make some measurement on all big coil respect to ground.
when you confirm have no shorted, then you can connected the power cord to test voltages

[bicalov]

Re: HP G7-1000 series R22 mobo problem

thx meritosari, I will check

[bicalov]

Re: HP G7-1000 series R22 mobo problem

Update,
Measured all big coils and PL18 and PL19 show short.
PQ37 show short on pin 4, leading to PU1 pin 29.
PU1 pin 36 show short on pin, but not on resistor PR4 and cap PC4, so it must be PU1
Removed PU1 and short is gone. Removed PQ37 first to be sure it was PU1
Now wait for new ISL6265A for which I can't find a compatible.
Thank so far guys