After checking the address lines, ADDR2-3 seems dead (short to GND), ADDR4-5 is not healthy (very low resistance to GND compared to other lines, but still has signal on power on).
And its looks like another CPU kicked the bucket (lifting these pins of the cpu restored the resistance on the bus)

If 12V is missing, you don't get RGB output. Actually seems a common fault. Seems like the dac fails (cant see 12V on it, though there was), but never bothered to really look into it. https://www.exdwh.com/data/STV8438CV.pdf You can even check the gerbers: no 12V trace goes to the RGB DAC. Not ever...

exxos wrote: ↑Sun Sep 02, 2018 6:00 pm No video can be bad NVRAM settings, or missing 12V on the video DAC.

Tbh the video DAC does not need 12V but the PAL/NTSC encoder does -- if you have it (and a modulator) installed.
If the internal fan spins, then you have 12V.

A while back bought a broken Falcon mobo off ebay, but after a few tests and checking of logic chips in a TL866 programer (result: no tested chip worked) I concluded all the chips have been killed off :( After some time of gathering parts and changing, finally ordered the last parts: AJAX, COMBEL, S...