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820-2915 L9510 pin 1 (PP1V0_S0GPU) short to ground

P

protocold

Member
When I received this, the LVDS connector on this board is trashed and someone shorted F9700 with solder.

I have measured diode mode for all big coil and found out that L9510 is shorted to ground. I removed L9510 and isolated that the short happen on pin 1(PP1V0_S0GPU).

where should I go next?
 
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2informaticos

2informaticos

Administrator
Staff member
You can compare with good board, but looks too low for me.
Very likely dead GPU; you should try disabling it.
 
P

protocold

Member
196 ohm for good board at L9510.

I have already flashed the gmux to disable the dead GPU. Perhaps the GPU is just hard shorted somehow then?
 
2informaticos

2informaticos

Administrator
Staff member
Does your board stays on with that short?

You need to isolate that power supply.
Remove R9500 and try again.
 
P

protocold

Member
I removed R9500. L9510 and C9510 are also removed at the moment.

The board will stay on with fan spin and it will chime, I have replaced F9700 and it measure 12.45v.

I will wait for the LVDS connector to arrive then.
 
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P

protocold

Member
Actually the 3 PPVOUT_S0_LCDBKLT pin pads for the LVDS socket are ripped by the previous guy who attempted the fix..

Can i just use regular tiny jumper wire to bridge those pins on the new LVDS connect back onto PPVOUT_S0_LCDBKLT signal? will those jumper wire too thin for the job?
 
P

protocold

Member
I just found out that PPVOUT_S0_LCDBKLT is shorted to ground as well.... but diode mode reading at L9701 is normal when compare to a working board.

what now?
 
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P

protocold

Member
Actually I found out the previous guy had created this crap next to the LVDS connector and messed up the PPVOUT_S0_LCDBKLT pins completely.

That person probably pushed the ground shield onto the micro via for PPVOUT_S0_LCDBKLT causing the short. When I use alchol and cotton bud to clean that spot there are lots of black crap coming out..I suspect this was burnt by bad solder iron somehow?!

After some cleaning and unbending the ground shield and the short is now gone. Diode mode reading now seems normal compare to a working board.

I wonder if this is still safe to continue ?
 
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P

protocold

Member
ok, i have now soldered a new LVDS connector back and also jumpered the 3 missing pins on the LVDS to PPVOUT_S0_LCDBKLT.

Backlight doesnt work. I can see images on the screen with a led torch shining on the screen.

PPVOUT_S0_LCDBKLT seems to be jumping between 19v to around 25v.
 
2informaticos

2informaticos

Administrator
Staff member
Did you try known good screen?

Seems that backlight us cycling.
You may need to change U9701.
Check traces and solders around it.
 
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