In this series of earlier posts and I had posted some notes on acquisition and repair of an all original MAC 128k. One thing I didn’t mention is that the video on the machine was a bit intermittent. This has bugged me a bit and yesterday, I decided to figure out what was going on. The symptoms were intermittent video, either working normally, or completely black. Taking the machine apart, I determined that wiggling or touching the connector that leads from the digital to analog board could cause the video to go on or off.

Some websites and an old book, “Macintosh Upgrade and Repair Secrets”, say that this sort of problem is often due to bad solder joints on the connectors on the analog board. Following those directions, I pealed off the plastic cover and resoldered the joints on the analog board. However, this did not affect operation. Figuring that I had nothing to lose, I then touched up the joints on the connector on the digital board. Wiggling this connecter seemed to affect the problem, so I was kind of hopeful that resoldering that connector would do the trick. Sure enough, the intermittent operation seems to have disappeared once I resoldered those joints. Now, I just need to find some foam with adhesive on both sides to use, to put the plastic panel back over the analog board and I think I’ll be back in business.

I hope I don’t have any further issues, at least for a while. By the way, my opinion is that those connectors could have used a bit more solder in the first place, and this probably contributed to the issues.

This experience with a MAC 128k shows how even a lightly used old computer that is in excellent cosmetic condition, may need some work in order to get it running like it was new. I had three problems with this machine that needed addressing.

Note that there are high voltages in this system and it should only be operated by experienced technicians when the cover is removed.