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Help! Power supply

Y

Yzzerdd

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Oct 20, 2006
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I think the power supply in my AT&T 6300 is shot. It had been good, but over the last few months I've noticed problems. 3 months ago, my HD would park itself, whil the system is on. It only parts when power is removed. Now, on start up, the monitor doesn't get video, so all I get is a gray screen. The HD much of the time doesn't do anything eith, nor does the floppy. Some times, the only thing that powers up is the system fan. Then at other times it works fine, for a few hours. Anyone think it is the power supply, like I do? I sure hope it is fixable, I can only imagine the difficulty of finding the exact model for this computer.

--Ryan
 
If you had a picture of this power supply, it would be a huge help. I have a pile of old power supplies, but mostly generic Baby AT style and a few AT and XT clone style. While it wouldn't be origional, you might even thing about finding a way to fit a baby AT supply in the case, they're small so they ususally fit, have plenty of watts, and you can use a chunk of sheet metal from a junk ATX case to make an adaptor plate. If I knew what yours looked like, I could tell you if I had one.
 
If it's a generic power supply, then it's not worth it, but...
If you're REALLY careful, and know how to use a soldering iron, have some solder (& a sucker too if possible) you could try repairing it, it really sounds like the 12V has got an intermittent fault, probably down to a crystalised joint around something that gets hot on the 12V side of things.

After it's powered down leave it 20 mins or so, then carefully open the case and short out the big reservoir capacitors with a plastic handled screwdriver. This is the bit you really have to be careful with, as one of those capacitors can hold enough charge to stop your heart. They normally discharge within a few seconds of powering down the supply, but if there is a fault they can still hold charge for weeks. putting a screwdriver across the terminals is a good way to make sure.

trace the low voltage bits back from the output wires, and look for bad solder joints. I'm fairly sure you'll find more than one.

Suck them clean if you can, and re-solder them, do as many others in the same area as you can before you get bored.

Check you haven't left any blobs or whiskers in the works, put it back together & give it a whirl.
 
The only AT&T box I've ever seen was a socket 7 machine. It was nothing special, just a white box clone with an AT&T logo on it. Are you sure its a proprietary PSU?
 
This one is running an 8086, at 8MHz, much less than socket 7. I am relatively sure it is proprietary, because of it's connectors and such to the motherboard. Pictures will come later this evening
 
I have the technical reference for the AT&T PC 6300 (it was my first machine as well, still have it) and I would be happy to scan the power diagrams for you. It should be possible to alter an existing power supply to work.

I'm at work at the moment, so I'll have to scan these when I get home in a few hours.
 
I'd definatley appreciate that. BTW: I may not have those pics untill tommorow, I am exausted after moving muliple humongous desks(one rool-top). Hmm... Doesn't look like me have a smiley for tired.. Oh well, I guess the text for it would be :)sleep) or :)tired). :lolsign:

--Ryan

EDIT: had to take off the : at the end of sleep and tired, it kept making a smilie. ; wouldn't even work, it made a wink.
 
My 7-yr-old son Max broke his clavicle falling off his bike tonight. No scans, sorry :) Bug me via trixter _at_ oldskool _dot_ org if I forget in the next two days.
 
Ok, he's back in a sling but I'm off the computer for the next few days, sorry. If I'm still not back on in a week, email me. I may be the only person left on the earth with the full tech ref for the AT&T PC 6300 :) so don't let me forget!
 
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