After recently purchasing another Apple IIgs I brought it home to find it containing a Vulcan GS, a Transwarp GS (!!), a Roger Wagner audio digitizer, and a Chinook 4Mb RAM card.
However, shortly after acquiring the IIgs, the fan in the Vulcan power supply died. No sweat I thought, this should be a five minute fix! How wrong I was... After replacing the fan with a known-good surplus fan I had not in use, I put the Vulcan GS power supply back in and <click!> <click!> <click!> <click!> <click!> <click!>... The power supply was shutting itself down, starting up, shutting down... You could see the power light on the motherboard flashing on and off repeatedly. Damn!
The symptoms are usually indicative of too much load (i.e. a short) or a lack of load. The fan swap was a simple replacement with no soldering (just plugged into the power supply circuit board), so I was a bit surprised. I re-opened the case and checked for anything obvious (foriegn debris, loose wires, etc). Nothing. Hmm... sounds like one of the electrolytics may have died. So a day or two later, I replaced every single electrolytic capacitor in the power supply. I turned it on confident that this will fix it. <click!> <click!> <click!> <click!> <click!> <click!>... Nooooooo!!
I spent ages tracing the circuits and testing here and there... but, whilst I'm handy with a soldering iron, I'm really only a pretend hardware guy - and this was rapidly exceeding my hardware troubleshooting skills.
After a few days of testing and pulling my hair out - I decided that enough was enough! Time to replace the innards of this power supply. I'd heard of others doing this, and I'd already performed the same thing on a normal IIgs power supply using the same strategy as Andrew Webber, however the Vulcan GS is a different beast as the space is very tight. I'd heard of the Meanwell PT-65B being used in the Vulcan GS, and I was initially going to do the same. The local supplier I'd used previously for my Meanwell power supply had sold out and there would be a wait of several months. Hmmm....time to look for another power supply?
And after doing several hours of research, I had found one. Not only does it have the right dimensions, it has a quad output supply. No need to rig up a voltage regulator to derive the -5V from -12V. Yes!
I bought mine from Jameco at the bargain basement price of US$13.50 each (I bought 2).
Here is the installation procedures I used to modify the power supply to fit inside the Vulcan GS:
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