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820-3332: Bootups but no image, backlight, or HDMI feed.

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cobragfox

Member
Have a 820-3332 with image issue. It boots up and chimes, but no image to the display or to HDMI.

LCD_PWR_EN: 0v
EP3V3GPU_EN: 0v
GPUVCORE_EN: 0v
PPVCORE_S0_GFX_REG: 0v (resistance check is 16ohm approx on PH2 and 18ohms approx on PH1) but assuming this is due to the GPUVCORE_EN being 0v

I replaced U9100 with no change. (Does this chip have to be from a donor board or can one purchase online (like digi-key) work, as this is what i did)?

Any suggestions
 
2informaticos

2informaticos

Administrator
Staff member
Post volatges at pins 9 and 28-30 for J9000.
Pins 28-30 must get voltage at least few sec when hear chime.
Then LCD_HPD should go high too.
LCD supposed to be connected...

Did you try a known good panel?
 
C

cobragfox

Member
All measurements done with know good display connected

Pin 9: 0v
28-30: 0v (u9000 pin2 5v, pin1: 0v).

Had the probe on each pins before applying power to the board for each test.
 
2informaticos

2informaticos

Administrator
Staff member
Any short there?

The LCD panel is not detected, so no image...

Pins 28-30 must get voltage (for short time) even without screen connected.
 
C

cobragfox

Member
There is no short on any of this pins, Without the screen connected, pins 28-30 is reading 0v. I believe the issue may be due to the enable signal thats reading 0V, but i replaced the GMUX chip already, U9100
 
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