On 5 February 2014 09:17, Mark Wickens <mark at wickensonline.co.uk> wrote: On 05/02/2014 08:00, Cory Smelosky wrote: On Wed, 5 Feb 2014, Google wrote: On 5 Feb 2014, at 05:26, Cory Smelosky <b4 at gewt.net> wrote: So, my VAXstation 4000/60 shut off and I had difficulty getting it to turn back on. Seems like a not-to-abnormal situation, right? PSU's getting old or overheating protection kicked in? That's not the weird part! It may have overheated, I do know power switches can get flakey in VS4000s but the symptoms tend to be it won't turn OFF not on't turn ON but I guess if the switch is not contacting correctly it could be that too. the switch isn't, as far as I can tell, directly controlling the current, it is in some kind of latch circuit that unlatches when you flick it to 'OFF'. I think it's an early 'soft-power' implementation. I moved the UPS further away. Very possible it got bumped and got too close to the UPS. Full explanation: http://dectec.info/vaxstation-4000-power-switch-issues-and-cleaning/ Thanks! Also talk to Mark Wickens, he's had a few issues with 4000/90 PSUs. When I rebooted the system...it had decided it was suddenly /2015/ and all the licenses expired. I've heard of systems resetting to the past when something happens...but NEVER the future! That is odd, but Mark W remarked on my blog about one PSU failing and spiking his 4000/90 so badly it fried several parts, it's possible it could have upskittled the TOY clock? Fans would click for a second and then kick right back off. It stopped doing that until I removed all the drives. Plugged 'em back in after opening the PSU to look for obvious faults and found none. Everything is working fine now...Strange. I had a hard disk taken out by a power spike. I also had firmware corruption that required reflashing the EEPROM, but I don't remember if that was related to the PSU. They draw 30 watts when switched 'off' so it's definitely worth turning them off when not in use. Twitching fans might indicate over-current protection kicking in. I know one thing however - switched mode PSU experts are few and far between! Don't I know it! I think that if you want to collect vintage hardware you either need a tame PSU repair man, or you need to start learning. I don't have such a person to hand, or at least not one I want to ask too often anyway, so I need to learn. This is happening a bit, but I am very slow, and I need more test equipment, like the ESR meter that has been suggested. Regards Rob