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I have 28V on the board but seems like it isn't getting to U2 some how. It's measuring 0.7 - 2.4V. Only 3.2V at C12

C19 measures in range in circuit, but hard to tell without completely removing it

It also has a mod on the height potentiometer toggling between 151k ohm and 76k ohm

Hey all, does anyone know which part of the Lisa video board is responsible for vertical deflection? It worked in the seller's pictures but complete collapse when I turned it on. Probably broken solder joints right? Or which capacitor should be replaced first

Thanks for the updates! I have one that was working before which I think has the exact same issue. Where do you get the replacement parts?

Does anyone know where the right most trace beside UA15 and UB15 is supposed to go to? The one corroded with green goo. Is this the trace to adb power or something else?

UD7 and UD8 are pretty hot to the touch. The other chips in that row are warm but not hot

Yeah, Unfortunately I don't think it's the monitor 🥲. It's an 12 inch Apple RGB and still works with my other iifx. I know there are 2 breaks around ub15 for the serial port but that shouldnt affect video and have been there for a while even before when it was working.

My C32 is 2.2V, is that normal? A32 and B32 are +12V which is correct A1 and B1 are -12V and C1 is 5V seems to me that A2, B2, C2 aren't voltage lines on mine

Yeah, about the same (showing 13-14 for me). So that seems correct to me! Recapped the rest of the board except for the radials and still no video as expected. I feel it's really unlikely that corrosion can eat through traces within an hour so that really makes me suspect it's one of the chips...

The voltages on those pins all seem correct. Does anyone know if C9, C10, C12, C13, C21 should beep when testing on both ends of those caps? Seems strange that it would even though the voltages are correct

I have yet to swap and try another psu since all voltages seem correct. 12V on yellow, 5V on reds and -12V I haven't recapped any of the radial caps and a few 47 16v but don't think those can affect nubus right?

Video died on a working Macintosh IIx after leaving it on for a while. Turned it off, waited an hour or so, turned it back on and now no video. It still chimes and boots fine, just no video, completely black screen. Tried the same video card on another machine and the card works. Tried another...

sent PM!

It's difficult to see but likely something inside the ribbon then. All exposed pins outside of the ribbon are connected between the 3rd and the 4th cable. A replacement lm64p791 is hard to comeby nowadays

if it's the row driver I would be losing 1/4 of the screen right? not only 1/8

I reflowed the ribbon cable right under those lcd caps but that didn't seem to make a difference. I noticed that usually if it's a ribbon issue I should lose 1/4 of the bottom screen right and they'll show up yellowish?

Check all the address and data lines around the asc chip. Mine turned out to be the r/w line

actually, listening closely to the speakers, there is the famous mac death chime a few seconds after a white screen comes up. It is very very faint, even with headphones. Not a caps issue because it's already been recapped and the sound is loud and clear after it boots. What's weird is that it...

oh you are right! CONTROL-COMMAND-RESET does seem to boot it faster. Weird. Tried clearing the pram a few times but that didn't help