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Hi Alex, I haven't switched it on for about a month so I'm no further ahead! Sounds like you have changed most things! Do you have the resetting problem too?

Hi everyone, Well i thought i had the Mac in a stable condition after all your great advice but having gone back to it after about 10 days its back to the constant reset on boot issue. I have checked the voltages while it is doing this and its reading (at the drive port) 4.75 and 12.3v. If i...

It's version 7.1, I would really appreciate the ram upgrade, I'll dm you.

Yes I do

One more update, i have been starting the computer up and testing it over the last couple of days. Basically it starts, wobbles for a bit then boots and all is well. I think i may leave it alone and see how it goes. Just one more question, after it boots it shows it has about 800kb left of the...

Ok, another update! I have put the hard drive in and it spins up and accesses without a problem (so far). So hopefully the cap change fixed the hard drive issue. Still have to wait a few minutes from cold for it to stop wobbling. I might try reflowing some solder joints around the power supply...

Yeah I read about the optocoupler, I have ordered the diodes that are suggested on that thread. If I get it to a state where all that is wrong is that it takes a few minutes to boot without screen wobble I'm not sure if it's worth changing more components incase it triggers more problems!

Yeah definitely, it doesn't currently have a hard drive in it, I need to collect it today. Once I have it in hopefully it will read it reliably and the remaining issue will only be a wobbly screen for a couple of minutes.

Hi Josh, This is with all replacement caps.

So I've made some progress thins morning! I tried adjusting the potentiometer again and got it to exactly 12v with the screen still wobbling. After a couple of minutes there was a beep and it booted to the question mark icon! After another few minutes the screen stopped wobbling. So I'm now...

Ok having slowly moved the potentiometer from side to side there is a bit of an improvement. There is no resetting now, just a wobbly screen. Whereas before the wobbly screen would steady after a few minutes now it is staying wobbly. Could it maybe be a diode problem? Taking the board out a...

Brilliant, found it thanks. I'm gonna give it a go.....

Any idea where on the board pp1 is located? I'm looking now and can't see it

Thanks very much for that, gonna take a while to get my head around them!

Thanks for that, I'm pretty sure I have the correct caps in the correct places now. Not sure if I should desolder them and check the polarities, I was very careful putting them in though!

I have tested the outputs on the FDD connector. The results are as follows; Pin 5 -11.75v steady Pin 6 +4.33v fluctuates when it resets Pin 7. +11.07 fluctuates when it resets Pin 8. +11.07 fluctuates when it resets I haven't had a good look through the schematics yet, will do later.

I don't have the schematics, i couldn't find them. Do you have a link? I do have an oscilloscope so i will have a look at the 5v supply line Thanks for the link, the only difference is the cap at the top of the cluster on my board was 1000uf 35v and on that picture it is 470uf 50v. I know that...

I haven't checked the voltages yet, I could find the right schematic. Didn't think about the floppy drive connector! I'll check tomorrow and report back, thanks for the quick replies!

Hi Philip, No it's in Hertfordshire, we have a small vintage computer room in the museum which we are working on at the moment. I've heard about the new one in Derby, looks great!

Hi everyone, Im currently trying to fix up a Mac Classic for a museum i volunteer at, but am not having a huge amount of luck. I will describe my process so far. When the Mac was given to us it wouldn't boot from the hard drive, it would only produce a question mark icon. It did, however, boot...