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IBM 5160 smoking PSU

B

Bernie250

Member
Joined
Dec 17, 2017
Messages
21
Location
the Netherlands
I got me a pretty IBM XT 5160 yesterday.
It's been on someone's attic for 1 or 2 decades...
So I take the thing apart, 5151 included, cleaned the outside and remove all the dust from the inside.
Everything looked just fine, all the parts are perfect and shiny.
So I hook it up, power it up and than there is that smell.
That smell of you did something bad, you let the smoke out!:mad:
I traced the source of the smoke leak to the PSU and guess what?
The transformer melted on one side!:confused:

I expected some issues with caps or the likes but not the tranny melting?
Isn't that supposed to be the most solid piece in the PSU?
Anybody else had similar issues?
The PSU was an ASTEC AA12151.

I guess I need to get myself a replacement power supply.
Any suggestions anyone?
 
The most expensive and hard to find piece, Some manufactures include multiple fuses / fusistors to protect the transformers but if one goes short there's not a lot you can do unless you can find another suitable transformer. PSU's suitable for the 5160 do appear on ebay or some people have gone the transplant route, Find yourself a suitable AT or ATX PSU and transplant the innards into the 5160 PSU case.
 
I'm going through a big lot of equipment from a recent pick-up and actually have a PC/XT 63.5W supply, in the box that its replacement came in. Supply tests OK on my D'Asaro Designs load tester, and also runs a 5160 640K motherboard just fine. PM me if you need it, it may be too expensive to ship depending on where you're located. Do note that you'll want a higher wattage supply if you're going to run an old MFM hard disk (I suspect that's why this one was replaced).
 
OK so here's the offending tranny.
I pulled the plug as soon as I smelled trouble, which was right about after HDD drive spin up completed.
As you can see damage is not that bad, but black goo started to come out together with some smoke and that smell.
album.php

Is it beyond repair?

Secondly, if my math is correct wouldn't I need a 130W replacement PSU? :
album.php
 
Bernie250 said:
OK so here's the offending tranny.
I pulled the plug as soon as I smelled trouble, which was right about after HDD drive spin up completed.
As you can see damage is not that bad, but black goo started to come out together with some smoke and that smell.
album.php

Is it beyond repair?

Secondly, if my math is correct wouldn't I need a 130W replacement PSU? :
album.php
Click to expand...

You could probably have the transformer rewound; but the cost will far exceed that of a complete replacement power supply.

Also yes you probably need a 130W if you are running a HDD. Some people have had success using a 63W but the results are sketchy at best.
 
damn. A blown transformer is probably the only part of a PSU (and pcb) that is not feasibly replaceable. Literally anything else can easily be found and replaced. Also, in my experiences transformers generally don't go bad, something makes them fail.

I can't think of the phrase right now, but I would consider that PSU beyond economical repair. Can we get a few pictures of the damage? It might not be as bad is it has been made out to be.
 
Here it is :
attachment.php

attachment.php


You can see it has deformed underneath the copper foil and the goo coming out the side.
I'm not familiar with the schematics of the power supply but since it's not a switched power supply I'm guessing :
-mains power is connected to one side (230V in my case)
-a rectifier of some sorted on the other
-followed by some caps to stabilize the voltage
-and then some other parts to split up the voltage into usable levels. (-12, -5, 5 & 12)

What do you guys think?
Bin it? Of fix it?
 
I'd replace the unit. Or do what chuck suggests, and put a "new" supply into the old shell. It sounds like a fun project to be honest.
 
Looking at the photo it doesn't look blown, deformation under the copper foil is normal. I've never had a switch mode supply where the main transformer died, the feedback transformer in an apple supply yes but never the main one.
Is the goo you describe wet?
Could it have come from another component?
For instance when the RIFA caps blow they spray dark brown goo everywhere.
There is no goo inside that transformer to leak out. Just insulated copper wire on a plastic form and lacquer to hold the windings in place.

I'd be looking elsewhere for the fault.
 
Bernie250 said:
...I'm not familiar with the schematics of the power supply but since it's not a switched power supply I'm guessing :
...
What do you guys think?
Click to expand...
I think it's a switching supply; what makes you think it isn't?
Bin it? Of fix it?
Click to expand...
Replace it, unless you find a short that only overheated the transformer without actually seriously damaging it.

m
 
I would also be looking elsewhere. I second you've mistaken a bad conformal coated transformer for blown RIFA's. It's rare for transformers to just randomly burn up.



Or, since we know what the fault is and it's supposedly non-repairable, hang a load off it and plug er- right back in for some fireworks.
 
word of caution, the magic smoke takes DAYS to fully dissappear. i popped a transistor last week or so. stank my garage up for almost 3 days.
 
David_M said:
Looking at the photo it doesn't look blown, deformation under the copper foil is normal. I've never had a switch mode supply where the main transformer died, the feedback transformer in an apple supply yes but never the main one.
Is the goo you describe wet?
Could it have come from another component?
For instance when the RIFA caps blow they spray dark brown goo everywhere.
There is no goo inside that transformer to leak out. Just insulated copper wire on a plastic form and lacquer to hold the windings in place.

I'd be looking elsewhere for the fault.
Click to expand...

OK, let's get to the bottom of this. I hate assuming things.
So how do I take that black plastic thing apart that's binding all the cables together out of the metal casing?
(without damaging it)
I have decades of experience in operating computers all sizes and shapes but not in repairing power supplies.
So I will need some help from you guys.

attachment.php


I found the RIFA's you are referring to. On some other forum they refer to these as ticking time bombs....
Seems mine are in less than optimal condition.

attachment.php


No black goo though. And the goo on the transformer has solidified.
 
Bernie250 said:
So how do I take that black plastic thing apart that's binding all the cables together out of the metal casing? (without damaging it)
Click to expand...

A small section of it should pull out sideways from the rest of it. You may have to twist it around in the hole so that the small section lines up with the metal cut out.
 
The RIFA's will need replacing but i can't see anything obviously burned in the pic, Is the Fan OK, Can you turn the fan blades freely.
 
The fan is fine, it will spin if I blow at it, I don't even have to touch it.
I'm seriously considering recapping the power supply to see if that helps.
Perhaps one of those (RIFA) caps started venting electrolyte on or near the transformer.
My nose told me the smell was the strongest there and I took the crappy coating job for melt damage.

For me this is just one big adventure so recapping is sheer entertainment.
And I could use the practice...
If it works that's great, if it doesn't I'll perhaps loose a handful of Euros on it.
Does this make sense?

If I do choose to recap, will I be OK if I just replace the big electrolytic caps and RIFA's?
Or do I also need to replace the....what is that brown thing mica? caps?

What do you guys think?
 
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