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IBM 5170 power supply blew up

offensive_Jerk

offensive_Jerk

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I had a post HERE about an issue with a 5170 fixed disk card being wonky. I had replaced the three caps on the bottom of the card just to try and see if that helped... It didn't.

It was advised to try the card in another machine which I was doing. This is a 5170 that I hardly use. The old Seagate was being cranky and noisy when I was first attempting to boot which I find these 5170s do to me. I have to "warm" up the hard drives for them to boot. This one squealed more than the others. I got a couple of 601 disk errors at boot, and then was able to boot the hard drive.

The machine booted, but failed reading a file and locked up. I rebooted and then the system locks up after posting. I figured command.com or something got corrupted on the lock up. I boot from floppy and ran Norton Disk Doctor and it marked some bad sectors. Then I rebooted again a few times and the 601 error went away.

Suddenly it wouldn't boot from the hard drive anymore. The last message I see on screen was a hard disk error of some sort (can't remember) and then smoke came billowing out of the computer. I had the top case off and it seemed to be coming out by the power supply.

I took the power supply apart and noticed what I believe to be filter caps are blown. One blue on appears outright blown, and damaged the nearby red colored cap. I also noticed the other blue cap has a crack in the center of it. Smelly smoke and lots of it.

Is there any problem with any of the computer's circuitry that would have caused these caps to blow? Could it have been the questionable Fixed Disk adapter that I replaced the caps on? Or something with the hard drive that maybe shorted the power supply since it suddenly stopped detecting at boot? I'm guessing the answer is no, since these are "line" capacitors but I really don't know anything about this stuff when it comes down to it.

Would I be alright just installing all new caps in this section of the power supply? It seems the other board on the PSU seems to have some questionable caps of the smaller physical size that appear somewhat bubbled out. Not sure how far I should go with this.

caps.jpgsmoke.jpg
 
From what I can see, these caps are on the AC input side of the PSU. They're not "filter" caps in the sense of DC smoothing, but rather to prevent EMI from radiating back into the AC line.

There are purpose-made caps "safety" capacitors for this purpose. Usually X2-rated poly film caps. This topic has been discussed before on this forum.
 
I've read some posts on this, but I just wanted to confirm that it's unlikely that anything on the computer side would have caused this, like a short on the motherboard or peripheral for example. I'm just guessing the hard disk going offline right as this was happening was a coincidence. Might just be paranoid about it.
 
offensive_Jerk said:
I've read some posts on this, but I just wanted to confirm that it's unlikely that anything on the computer side would have caused this, like a short on the motherboard or peripheral for example. I'm just guessing the hard disk going offline right as this was happening was a coincidence. Might just be paranoid about it.
Click to expand...

Those wima capacitors probably have blown many years ago, as they always did on every power supply that used them (and the much worse RIFA). They should be replaced with good quality X1/X2 capacitors.
Frank
 
I'm not familiar with these types of components. I see a few of these that I removed seem to be y/x2 rated.
I am having a hard time searching for these on Mouser. They also offer 3 different types of "Safety capacitors." Not sure which one would be the best choice. They have Polypropylene, Paper, or Polyester.
They also have several choices for type: Ceramic Disc, MLCCs, Safety Film, and Suppression film. Do I want Safety film?


The ratings on the caps I removed are:

QTY 4: Y/X2 .0047uF 250v
QTY 3: X2 0,1 275~ (I assume this means 0.1uf, 275V?)
QTY 2: Y/X2 .01uf 250v










Untitled by offensive_jerk, on Flickr
 
iz8dwf said:
Those wima capacitors probably have blown many years ago, as they always did on every power supply that used them (and the much worse RIFA). They should be replaced with good quality X1/X2 capacitors.
Frank
Click to expand...

In other words, they fail with age and there is nothing to "prevent" this. It's a feature to force replacement of older components that are no longer functioning. Replacements are cheap and easy to source. You can also run without them entirely if you wish but your system will no longer be FCC compliant.
 
offensive_Jerk said:
I'm not familiar with these types of components. I see a few of these that I removed seem to be y/x2 rated.
I am having a hard time searching for these on Mouser. They also offer 3 different types of "Safety capacitors." Not sure which one would be the best choice. They have Polypropylene, Paper, or Polyester.
They also have several choices for type: Ceramic Disc, MLCCs, Safety Film, and Suppression film. Do I want Safety film?


The ratings on the caps I removed are:

QTY 4: Y/X2 .0047uF 250v
QTY 3: X2 0,1 275~ (I assume this means 0.1uf, 275V?)
QTY 2: Y/X2 .01uf 250v
Click to expand...


Planning on ordering the following:


Replacement for QTY 4: Y/X2 .0047uF 250v
https://www.mouser.com/ProductDetai...=sGAEpiMZZMu3dWSqd4Tl0M18jU2Z1emC8fsP2s4HX84=


Replacement for QTY 3: X2 0,1 275~:
https://www.mouser.com/ProductDetai...3dWSqd4Tl0Fd7dHVopjbi8f0SngMoodfPSeA4cWRTTw==

QTY 2: Y/X2 .01uf 250v
https://www.mouser.com/ProductDetai...3dWSqd4Tl0Fd7dHVopjbi3ikVpuYWuE9YcDm76vdtow== ??????

Can't really find a Y/X2 substitute. I read you can use a Y2 for an X2 substitute, but what do I substitute for Y/X2?
 
offensive_Jerk said:
I'm not familiar with these types of components. I see a few of these that I removed seem to be y/x2 rated.
I am having a hard time searching for these on Mouser. They also offer 3 different types of "Safety capacitors." Not sure which one would be the best choice. They have Polypropylene, Paper, or Polyester.
They also have several choices for type: Ceramic Disc, MLCCs, Safety Film, and Suppression film. Do I want Safety film?


The ratings on the caps I removed are:

QTY 4: Y/X2 .0047uF 250v
QTY 3: X2 0,1 275~ (I assume this means 0.1uf, 275V?)
QTY 2: Y/X2 .01uf 250v










Untitled by offensive_jerk, on Flickr
Click to expand...

Only the blue/golden variety need substitutes. The other ones (reddish) are very high quality usually and almost never fails (I haven't ever needed to substitute one).

Frank
 
iz8dwf said:
Only the blue/golden variety need substitutes. The other ones (reddish) are very high quality usually and almost never fails (I haven't ever needed to substitute one).

Frank
Click to expand...

I agree, the red ones are made by Mitsubishi and are close to 100% reliable. I have never seen one fail. On the other hand the Wima ones shown are prone to failure, the case insulation cracks and lets in water molecules from the atmosphere, because they are metallized paper types, this causes further expansion and cracking of the case and ultimate failure & smoke, so common with that type of X2 cap. So I would put the red ones back in after a capacitance and leakage check.
 
When I started my 5170 for the first time (probably in years) I think I remember a sound like a "spark" but no magic smoke. Is that likely that one of the caps blew?

I'm thinking I should order some caps and try to replace them. The IBM AT I think have no RIFA caps?
I have a Mac Plus and a period external hard drive, and the hard drive I did understand have the RIFAs, it does work, but I do not dare to use it anymore as I read about these RIFA caps.

What is the best way to go? I rather buy some caps and then open up and replace the caps in my computers at a slower pace, I do not want to open up all PSUs at once, as I do not have the time nor space to keep them opened until all is replaced. Some caps seem not easy to source either?

Are most of these PSU caps the same, so I can order perhaps 5-6 pcs and replace one machine at a time?
 
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