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IBM 5154 Magic Smoke released

Taffer

Taffer

Experienced Member
Joined
Jun 24, 2019
Messages
52
Location
Buffalo, NY
I've been trying to get my hands on a 5154 for years, so was very pleased to find one this weekend, even more so when it booted up and worked, but within 15mins or so out came the magic smoke.

20240427_214540.jpg

After some research on youtube, minuszerodegress, vogons, and here, I'm suspecting the "WIMA MP 3", which is the likely culprit. I've replaced RIFAs before my TRS80 Model 3 and it appears to be a similar line filter.

Is there anything else I should consider replacing while I'm in there (assuming the WIMA is the culprit)? Deoxit some pots?
Or just replace what's broken and move on with life?
 

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VERAULT said:
So did it work after it smoked? If so you have your answer on what it was and how not severe the issue is.
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I immediately turned it off and unplugged. I figured I'd better not turn it back on until I disassemble and investigate what blew up for fear of causing more damage.
 
Taffer said:
I immediately turned it off and unplugged. I figured I'd better not turn it back on until I disassemble and investigate what blew up for fear of causing more damage.
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I understand thats a natural instinct. However. Power it back on. Does the unit still power on and work? If so you simply blew the 120V AC supression capacitor.... NO BIG DEAL... That was my point.


If not no harm in trying it will just require further troubleshooting. My guess is the obvious supression capacitor which is just a daily thing on these old machines and not even worth mentioning.. Its like saying "I have been driving my car and now the oil is all black!" Its just something that happens after 40 years.
 
Taffer said:
Is there anything else I should consider replacing while I'm in there (assuming the WIMA is the culprit)? Deoxit some pots?
Or just replace what's broken and move on with life?
Click to expand...
When the safety/suppression capacitor blew in my 5154, and I had the power supply cage open to replace it, fitting a new capacitor was all that I did. I saw no reason to do anything else.
 
Great. I've got replacements on the way from Mouser. Like Adrian Black says, no reason to replace caps etc if they are working.
 
5154 back in business after replacing what turned out to be RIFA branded safety caps.

Also found an ibm EGA card ram expansion in my parts bin. Had no idea what it was until researching the IBM EGA card from this recent haul. What blind luck! Will now need to populate the rest of the sockets.
 

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You should scrape away as much of that brown/black glue on the board as you can. It's corrosive, and slightly conductive.
 
modem7 said:
Supporting photos at [here] and [here].
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If those are original standoffs, they are taller than I would expect. I see the expansion board propped out by the standoffs leaving less space to a card installed in the next slot over. That makes installation with the plastic shield present more important so as to not scratch up the backside on the neighboring card.

There are other possibilities for standoffs that may work. My reproduction card with the standoffs I used sits more flush. I believe I was not worried over the spacing between cards when I installed it. See here for other examples of spacing with the installed expansion module and standoffs present:
 
Thanks for the help about standoffs. I forgot to mention, I noticed a capacitor hanging off the board. Wonder if it was this way from the factory or if it was fixed by the previous owner (who was the original owner).
This is the back of the main board on the bottom of the monitor, visible when laying on it's face with just the cover off.
 

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Taffer said:
Thanks for the help about standoffs. I forgot to mention, I noticed a capacitor hanging off the board. Wonder if it was this way from the factory or if it was fixed by the previous owner (who was the original owner).
This is the back of the main board on the bottom of the monitor, visible when laying on it's face with just the cover off.
Click to expand...
I sense that you are seeking comment.

My 5154 does not have a capacitor soldered in that position (although there is a ceramic capacitor soldered on elsewhere, very far away). But a possibility is that my 5154 is earlier than yours, and precedes the time that an Engineering Change added the capacitor. If your 5154 is working as expected, then I suggest that you ignore the capacitor.
 
the3dfxdude said:
If those are original standoffs, ...
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Except for colour, they appear to match the ones shown on the 'ebay item' card at [here].

the3dfxdude said:
... they are taller than I would expect. I see the expansion board propped out by the standoffs leaving less space to a card installed in the next slot over. That makes installation with the plastic shield present more important so as to not scratch up the backside on the neighboring card.
Click to expand...
I have my IBM EGA card fitted in my IBM 5170, and I ended up deciding to leave ISA slot 2 empty.
 
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