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[SOLVED]820-4924 no internal video

T

tech333

New member
Hello,

I have an 820-4924 that came in with liquid/corrosion around U8330 area and does not display video to internal but does to external.
I have cleaned, replaced U8330 and tested with a working display. All components in the area measure correct but I am not getting LCD_PSR_EN.
Can someone tell me what the PCH needs to output that signal, or any information on how this circuit works would help.

Thanks,

Mike
 
T

tech333

New member
Hello Duke,

No LCD_PSR_EN so 0 Volts on L8300. I did test with a known good working LCD. Correct me if I am wrong but isn't 820-4924 a 2015 board. I have a known good LCD for 2013-2014 I can try if I am incorrect.

Thanks
 
D

dukefawks

Administrator
Yeah sorry it is 2015. The problem is that there should be a short pulse on L8300. This enables the system to identify the LCD. If there is no LCD detected it will go low again. So you cannot just check these signals after you turned it on. Check for a pulse on PSR_EN, preferably with a scope as multimeter may be too slow to catch. Check soldering on U8330 again and check if 3V is on pin 8.
 
T

tech333

New member
Yup, there is a pulse but voltage was not getting through U8300. Replaced and cleaned corroded pads and all is good with test LCD. Original LCD has a short on PP5VR3V3_SW_LCD. Do you think short could be in the display cable or is LCD shot?
 
2informaticos

2informaticos

Administrator
Staff member
Coonect only the cable.
If short persists, display should be good.
Don't power the unit; only check in diode mode...
LCD should have internal fuse in that rail.
So probably you have bad cable.
 
T

tech333

New member
No short with only cable connected. Signs of liquid in the display also.
Thanks for the help Duke and 2Informaticos.
 
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