Sorry I was wrong to attach the image ... the diagram of J8 is still different from my connectorThe schematic you have attached is J7 and you're looking at J8 on the motherboard. I've attached the schematic for the power supply, which has J8 on there.
unfortunately I have not yet measured anything because I do not understand how to do it ....Oh yes I see. I think if you measured the voltage across the yellow wire and ground, that should be 5v. If this is true then I think the AC line would be good, because the ac line feeds the 7805 regulator via a diode and then the output goes to J8 pin 5.
yes i have switching power supply!oh wait - you must have a switching power supply, hence no VR1 or VR2. That makes sense now. I think if you still measure the yellow wire to a ground point with your multimeter (red probe touching the metal clip on the yellow wire on the connector at J8) and then the black probe on a ground point on the motherboard it should read +5v
that makes more sense now. So pin 1 isn't needed on J8 then, thats why you only have four pin connector. The notes where at the bottom of those schematics.yes i have switching power supply!
Those numbers look goodOk i measured J8 connector (from power supply):
YELLOW= 4,98 V
ORANGE= 12,5 V
BLUE= 0V
Cpu signals???I concur, the DC voltages are fine. Good guidance @eight088.
So @Desperado, we have power, but no video signals at all. It is, therefore, not surprising that the monitor screen is black and that the initial fault is on the PET logic board.
So, what is your next step?
Dave
pin 40 - ResetSpot on my friend!
So, which ones?
Dave