Howdy!
I’m looking for some advice on fixing a G3 AIO “Molar Mac”. If I disconnect the CRT display cables from the wings card then it’ll boot perfectly fine with an external screen. However if i try to use the internal display then it doesn’t work. On start up there’s no chime, no LED, but the fan does start. The power supply kicks into action and the CRT seems to want to start but it makes a weird sound and the resistor at R726 gets very hot (not visibly but I can see it with an IR camera). So far I’ve tried:
Reflowing all the commonly known bad solder joints
Replacing the flyback transformer
Replacing the C5404 transistor (I believe this is the HOT)
I’ve tested and replaced many of the caps on the power supply, analogue board, and neck board. The few I haven’t all tested ok on a cap tester tool (I know that isn’t an absolute on them working.. but I’m not made of money!)
Replaced the R726 resistor with what I *think* is the same value, but it’s hard to be sure as it’s discoloured, but the rings came out to the same value as it tested as so I don’t think that was the issue.
Anyone have any ideas? Alas I have practically no PSU/Analogue board experience. I also don’t have any other AIO systems I can swap parts with (they’re practically impossible to find in the UK!). What I do have is quite a few spare 5500 style machines that I know it shares some of its components with.
Anyone have any ideas on what could be causing this or where I could find more information?
I’m looking for some advice on fixing a G3 AIO “Molar Mac”. If I disconnect the CRT display cables from the wings card then it’ll boot perfectly fine with an external screen. However if i try to use the internal display then it doesn’t work. On start up there’s no chime, no LED, but the fan does start. The power supply kicks into action and the CRT seems to want to start but it makes a weird sound and the resistor at R726 gets very hot (not visibly but I can see it with an IR camera). So far I’ve tried:
Reflowing all the commonly known bad solder joints
Replacing the flyback transformer
Replacing the C5404 transistor (I believe this is the HOT)
I’ve tested and replaced many of the caps on the power supply, analogue board, and neck board. The few I haven’t all tested ok on a cap tester tool (I know that isn’t an absolute on them working.. but I’m not made of money!)
Replaced the R726 resistor with what I *think* is the same value, but it’s hard to be sure as it’s discoloured, but the rings came out to the same value as it tested as so I don’t think that was the issue.
Anyone have any ideas? Alas I have practically no PSU/Analogue board experience. I also don’t have any other AIO systems I can swap parts with (they’re practically impossible to find in the UK!). What I do have is quite a few spare 5500 style machines that I know it shares some of its components with.
Anyone have any ideas on what could be causing this or where I could find more information?
