68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.
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. Posted by: mallynoshow on 2025-12-27 02:52:42
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. Posted by: bibilit on 2025-12-27 03:49:53
Yes, agreed, these ones are especially bad for caps being crappy. You will need to recap before you do much more, I'm afraid. Posted by: cheesestraws on 2025-12-27 04:20:43
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 Posted by: Byrd on 2025-12-27 04:21:03