Macintosh Classic II - Display Issue. Video Output With Corrupted Image

Hi everyone,

I’ve been lent a Macintosh Classic II that seems to have had very little use. I’m in Spain, where the mains voltage is 230 V. It probably has the typical capacitor problem, I assume. When it powers on, it doesn’t manage to show an image — I’m attaching a photo of how it looks.

I opened it and cleaned it thoroughly, and surprisingly it didn’t have much dust. I still haven’t removed the socketed chips or the memory modules to clean them properly — I’ll do that soon.

You can see a video of it powering on at this link: https://streamable.com/h1w9ef.

The photo shows how it was starting up before the first cleaning, and the video shows how it starts up now.

I’d like to know where to start.

I suppose the first step is to replace all the capacitors, although I don’t know if there’s anything specific to keep in mind with this model.

Do you know if it’s necessary to do any kind of repair on the CRT?


I appreciate any advice. Thank you very much.

Jorge.
 

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This is typical from bad caps and low voltage.
Check for the 5 volt rail at the HD Molex.

Don’t much you can do until caps have not been removed.
 
Yes, agreed, these ones are especially bad for caps being crappy. You will need to recap before you do much more, I'm afraid.
 
welcome Jorge,

The Classic/Classic II as you will discover from searching here was a very budget Apple design and will need recapping of both the analogue board and motherboard combined, with a deep clean of everything in the process. After this, pay some attention also to the optoisolator CNY17 and power control IC TDA4605 which often fail from cap leakage/age
 
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