Ibm Pc At 5170 - UK Vintage Radio Repair and Restoration Discussion Forum

liamoliver · 8th Jul 2007, 11:12 pm

I recently aquired a huge load of old computing equipment (including a CGA monitor for a PC 5150) from a house clearance in Kenton. In addition to a lot of rubbish taken purely out of pity I recieved this: an original PC AT. However, despite being told that it worked when last used (about ten years ago) it does not. Seemingly the power supply is at fault, as when plugged in the cooling fan does not spin up. There is a slight crackling noise coming from the PSU when turned on, and after a while it trips my circuit breaker. Is there any way this could be repaired, as I greatly doubt that I would ever find a suitable replacement now?

GMB · 9th Jul 2007, 9:58 am

Your best chance to repair it is to spot the failed components which will probably be capacitors. My experience is that if it isn't anything fairly obvious then it is hard to diagnose the fault.

I think the only difficulty replacing an AT power supply may be getting one that physically fits. It established a standard of the electrical details which didn't change much over the years and indeed I probably have a few slightly later ones that would power it OK. The variations were in details like the switch-on arrangements.

liamoliver · 9th Jul 2007, 7:44 pm

How exactly would I test the components? Can a faulty capacitor really crackle and trip the switch?

Nickthedentist · 9th Jul 2007, 7:53 pm

Quote:

Originally Posted by liamoliver

How exactly would I test the components? Can a faulty capacitor really crackle and trip the switch?

There are often capacitors connected directly between Live+Earth and Neutral+Earth. If one of these is faulty, an RCD will certainly trip.

I would find these capacitors and TEMPORARILY remove them both. This might get things working. But do replace them to prevent severe interference etc.

Note that power supplies like this contain big eletrolytic "can" capacitors, which can store quite a charge for a while after unplugging. Obviously, this can be a severe shock hazard, so be careful!

Nick.

8th Jul 2007, 11:12 pm	#1
liamoliver Retired Dormant Member Join Date: Mar 2007 Location: Nr. Harrow, NW London, UK. Posts: 104	Ibm Pc At 5170 I recently aquired a huge load of old computing equipment (including a CGA monitor for a PC 5150) from a house clearance in Kenton. In addition to a lot of rubbish taken purely out of pity I recieved this: an original PC AT. However, despite being told that it worked when last used (about ten years ago) it does not. Seemingly the power supply is at fault, as when plugged in the cooling fan does not spin up. There is a slight crackling noise coming from the PSU when turned on, and after a while it trips my circuit breaker. Is there any way this could be repaired, as I greatly doubt that I would ever find a suitable replacement now?

9th Jul 2007, 9:58 am	#2
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,100	Re: Ibm Pc At 5170 Your best chance to repair it is to spot the failed components which will probably be capacitors. My experience is that if it isn't anything fairly obvious then it is hard to diagnose the fault. I think the only difficulty replacing an AT power supply may be getting one that physically fits. It established a standard of the electrical details which didn't change much over the years and indeed I probably have a few slightly later ones that would power it OK. The variations were in details like the switch-on arrangements.

9th Jul 2007, 7:44 pm	#3
liamoliver Retired Dormant Member Join Date: Mar 2007 Location: Nr. Harrow, NW London, UK. Posts: 104	Re: Ibm Pc At 5170 How exactly would I test the components? Can a faulty capacitor really crackle and trip the switch?