02-08-2016, 10:05 AM
I've yet to work on a 7000-series. We have one at work, and there's every chance I could inherit it when we eventually decide to throw it away, but I don't think I will (although I'll probably pass it on via the forums rather than see it skipped). As lovely as it obviously is, it just doesn't appeal. not least because of the amount of custom Tek ICs contained within. The thing about curating old gear like this is that it has to be sustainable, so the fewer custom parts, the better. Specific CRTs and PSU transformers are unavoidable, as are switches and potentiometers in many cases, but if the electronics could be as "vanilla" as possible, so much the better 
HF PSU transformers tend to fail - the types used in Philips PM3215/7 and similar can fail with a short between 2 windings - that's because there's nearly 2kV between them. The same failure mode can affect many other 'scopes - I have a Tek 576 curve tracer at work that I think probably has the same fault. Odds of finding a replacement? Pretty slim...
I've got a good reputation for fixing switched-mode power supplies, and I run a 4 day course at work telling people how they work, and how to fix them. However, that reputation is partly because I've learnt which ones to try, and which ones to walk away from. Modern supplies tend to "wear out", with capacitors and start-up faults being the main problem - and that's thanks to designers (of ICs and switching transistors, as well as the overall supply) getting good, meaning that "blow ups" are much rarer than they used to be. But even so, if a PSU has blown up, you've basically got to be prepared to replace every bit of silicon and probably many other parts as well. Worth it sometimes; but often not. The trend to putting everything inside a single 8 (or 7!) pin DIP makes that easier for the smaller units...
HF PSU transformers tend to fail - the types used in Philips PM3215/7 and similar can fail with a short between 2 windings - that's because there's nearly 2kV between them. The same failure mode can affect many other 'scopes - I have a Tek 576 curve tracer at work that I think probably has the same fault. Odds of finding a replacement? Pretty slim...
I've got a good reputation for fixing switched-mode power supplies, and I run a 4 day course at work telling people how they work, and how to fix them. However, that reputation is partly because I've learnt which ones to try, and which ones to walk away from. Modern supplies tend to "wear out", with capacitors and start-up faults being the main problem - and that's thanks to designers (of ICs and switching transistors, as well as the overall supply) getting good, meaning that "blow ups" are much rarer than they used to be. But even so, if a PSU has blown up, you've basically got to be prepared to replace every bit of silicon and probably many other parts as well. Worth it sometimes; but often not. The trend to putting everything inside a single 8 (or 7!) pin DIP makes that easier for the smaller units...
