A Mac 128k that starts up and displays the Sad Mac with vertical lines has what- capacitor failure? A friend has asked, and I have never even seen one of these before, so any help would be appreciated.
More details please. This is not a common problem. Vertical bars would indicate incorrectly installed ROMs, but since you don't tell us if this is a new acquisition or something that happened since the last time you used it ... well you see the problem here. And what is the Sad Mac code?
I haven't actually seen the thing, but the chap whose PB170 I have been working on has just gotten a Mac128k boxed with all accessories, but that is behaving in the way described.
If it has been sitting in someones basement/attic for all these years it has been subjected to many seasonal thermal cycles. It definitely possible the ROMs could have creeped their way out of the sockets causing some kind of weird ROM error.
With only 3 electrolytic caps on the logic board, and with an absolute dearth of reports of bad caps bringing down these boards, it is unlikely bad caps are the root cause of your problem. Nevertheless, those 3 electrolytics do have meaning, and the fact is that by now all 3 are certainly on their last legs, if not dead. That's why I replaced mine with tantalum versions. You can read more about this in the description under my 128k logic board photo. (Don't forget to click "ALL SIZES" to see the large size.)