PS1Digital Solid Light No Signal

[nelsonra]

I installed my GPU flex and the PS1 booted successfully with Xstation installed on my PU-18 5501. Everything worked fine, but the sigtest revealed Xs on G3, G4, G5 were not properly connected. So I removed the GPU flex again and resoldered to the GPU getting better alignment now. I get a solid LED on the PS1digital but no signal to the TV. Confirmed 3.3v and 5v on the PS1Digital power pinouts. Focused on PCK and CLK connections and touched up the flex points to the chip many times. I still can't seem to get a signal. At least twice, the screen showed a gray screen with a few pixelated lines of color after a few minutes of being powered on. I powered off/on again and can't get a signal. I also checked continuity on the flex cable and the GPU legs for PCK and CLK. I noticed that if I touch the test lead (ps1 powered off) to PCK, GND, and 3.3 legs of the GPU chip show continuity to ground. Is that normal? I also put the test lead on the end of the flex cable following the trace from the PCK chip leg, I get continuity but also on GND and 3.3 legs on the same flex trace for PCK. Is that normal?

Thanks for any help for a novice to intermediate mod install hobbyist.

http://imgur.com/a/XLwjrZA

http://imgur.com/a/3sEyKqk

[UPDATE] 2021/03/04 - This was my bad. Two vias closest to the chip legs had filled with the tiniest blobs of solder and were bridging the flex cable from underneath. Unfortunately for me, removing the flex warped the original one and had to buy a replacement. Wicked up the vias and applied a thin strip of kapton close to the chip legs to prevent solder bridging. Soldered on the new flex and it fired up right away. Sigtest shows all points .

 

[CZroe]

I had the exact same experience with ground vias near the chip invisibly shorting to a pad underneath, but my issue was the audio IC/audio flex. I also had to remove the flex and use kapton. I also had the flex fail (broken traces inside) after all the troubleshooting. Unfortunatly, my replacement audio flex failed too as have others (I’ve installed dozens) so it is REALLY fragile and doesn’t tolerate much flexing (despite the name ). The traces break right where they leave the pads and go under the top conformal layer.

FWIW, you can’t rely on the PS1Digital’s test points for checking 5v short to ground. The audio flex is so fragile that the short may remain isolated to the PSX mainboard and there is no other 5v to the PS1Digital. I have bypassed the audio flex and wired power directly to restore some failed audio flexes.