Vintage IBM Power Supply Trouble

[vintageibm]

The IBM 5150 is a vintage computer from 1981.

The other day I turned on my 5150 for the first time in about a month or so. It powered on fine ran for about 25 minutes. Then it froze up and I turned it off waited about 30 seconds turned it back on. I was greeted with a crunching sound and an odd smell, no pops or anything like that. It never turned back on. So I removed the power supply from the case toke off the cover. I don't see anything really that "looks" bad. The power supply will give a short burst of power maybe a second or two then it's dead again? Any ideals? The fan in the PSU is good. I am thinking caps but none look bad.

[etnietering]

Re: Vintage IBM Power Supply Trouble

The crunching sound may have been something shorting. Pictures will help people identify and diagnose your problem.

[PCBONEZ]

Re: Vintage IBM Power Supply Trouble

Does it run with drives disconnected?

[Wizard]

Re: Vintage IBM Power Supply Trouble

Caution. These early SMPS blow up or refuse to work if attempted to run unloaded.

Some of these SMPS were contracted out to Zenith which means lot more in-house part numbers on components. :o

Cheers, Wizard

[370forlife]

Re: Vintage IBM Power Supply Trouble

I thought the majority of them were astec.

[Wizard]

Re: Vintage IBM Power Supply Trouble

We're talking about 1981-1986 vintage. Between 65W to 80W range for these depending on PC or XT models. These PSUs can not handle a hard drive and a controller at ALL.

And was not always Astec, some was odd make, many were Zenith sourced. Particularly Zenith SMPS design is *downright* strange.

Cheers, Wizard

[washu]

Re: Vintage IBM Power Supply Trouble

The original PC was the one that came with the weak 63.5 watt power supply. It had no HD option.

The XT came with a 130 watt and and had a HD standard at first. Only later was the XT sold with the HD optional. The 130 watt supply could even run two half hight drives.

As to minimum loading, the 192 watt supply in the AT required a fairly hefty minimum load. If they didn't have a hard drive they were shipped with a big power resistor hooked to the 12V line. It dissipated almost 30 watts.

[PCBONEZ]

Re: Vintage IBM Power Supply Trouble

Thanks boys.

First - I said "drives".
If you saw something hard you must have been looking somewhere else.

Next:
Having at one time had ~10 IBM 5150's and ~30 XT's running simultaneously in my garage,, I kind of know what they are.

The first forum I ever had a membership in was the IBM XT Club [or something like that.]

Retrofitting IBM 5150 with larger PSU's and 10-20Mb hard drives by way of kits was very common and probably the norm if it was used in a business.
http://www.myoldcomputers.com/museum/comp/ibmpc83.htm
The ones I had came from a school closure and only one 5150 that didn't have a hard drive.

~~

Since a shorted drive motor [regardless of the kind of drive] will keep the system down I'll repeat my question.

Does it run with drives disconnected?

.

[PCBONEZ]

Re: Vintage IBM Power Supply Trouble

I remember now. - The site for the IBM XT Club was "Uncreative Labs".
The site died when the owner quit but the members got together and restored in via Internet Cache, saved web pages, and their memories.
http://www.uncreativelabs.net/

If you look at the last member on this page
http://www.uncreativelabs.net/pcxtclub/oldxt.htm
He had a 5150 with a 20Mb Hard Card.
A Hard Card was basically a hard drive built onto an ISA card and the controller is integrated on the card.
I had a few of those back then too.