Dead AIM 65??

I would disagree with (6). My metric for how well a classic computer repair has gone is how few components I replaced before I found the real cause. My aim, of course, is to make measurements, think about them, then replace just one part (or a small set of parts, all shown to be defective) and get the machine to come up first time. Alas I am not that good. I would totally agree with that. You can do a lot with minimal test equipment if you really understnad what you are doing, and can think about the symptoms. Occasionally. I find myself saying 'If only I had a 64 channel logic analuser I'd get this darn computer working'. What this generally means is that I don;'t really understnad what I am doing. And after a lot more thought, I realise I could have found the fault with nothing more than a VOM and logic probe. I've recently been chatting to a chap in Germany about repairing an HP9810. I've suggested measurements to try (he knows what he's doing, he's jsut never worked on a bit-serial processor built from TTL before). I explain what he's looking for, what his results mean, etc. On the second chip replacement, the machine came up (and I think the first one he replaced was defective too). That, IMHO, is real debugging... Yes, the soldering iron is often the last thing you use when repairing a classic computer. Your first steps _must_ be to make measurements and think about them. And please don't get me started on the ridiculous idea of replacing random parts until the machine seems to work... -tony