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IBM 5155 not working under 220V

mrlinuxguy

New Member
Joined
Jan 5, 2013
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2
Location
Bordeaux, France / Prague, Czech Republic
Hello everybody! This is my first post here, but I'll probably be coming back for more, seeing as how I collect old computers (I can't believe I didn't see this site before). Since I don't know what else to say, I'll just go straight to the point of this post.

I recently acquired an IBM 5155 in working condition in the US, and had it shipped to a family member's home, where I was able to test it out (it worked fine, and I was able to run PC-DOS on it with a floppy, and write programs in BASIC).

Seeing as I only have one permanent place where I can store these (my collection) at the moment (and it's in Europe), I had to bring it back with me.
Upon arrival back here in Europe, I had set the power supply switch to 230V, plugged it in, and turned it on. Unfortunately, and much to my display, it doesn't turn on properly at all. Instead, it comes on for about a second and shuts off again.

During that fraction of a second, I do manage to hear the CRT starting up, if I keep my ear near the back of the power supply. The PSU's fan turns on as well, and the two lights on the front of the 5 1/4 floppy drives flicker on, before it all shuts off. Turning the main power switch to "O" then "I" again produces the same result.

Two things have crossed my mind: Either it was damaged (or something slipped out, eg card/cable) during it's way back here, or the PSU doesn't agree with 220V. Since I don't have a transformer here, I cannot test my hypothesis that only the 220V part of the PSU is't working, and I unfortunately don't have the time to tinker (let alone take it apart) around with it at the moment. I'd just like to be able to try and get some vague idea of what the problem could be, I'm heavily leaning on a faulty PSU.

Thank you for your time.
 
Welcome to these forums

Power supply

Refer to http://www.minuszerodegrees.net/5155/psu/5155_psu.htm

To test the power supply (at 220V), disconnect it from everything (repeat: everything) else in the 5155, and then per the web page pointed to, connect the supply to an adequate load. Then see if the power supply starts.

Finding an adequate load can be tricky. Per the web page, I found that approximately four to five standard IDE drives are required. You should not use any component of the 5155 as a load, because what you choose might be faulty (shorting out the power supply).

Significant 5155 infomation is at http://www.minuszerodegrees.net/index.htm
 
Tantalum capacitor

The IBM 5155 contains an early 5160 motherboard.

Failing tantalum capacitors is common in the 5155/5160 - see some history recorded at http://www.minuszerodegrees.net/vcf_motherboard_failure_history.htm
It could be that when you turned on the 5155 on arrival in Europe, a tantalum capacitor went short circuit.

See http://www.minuszerodegrees.net/failure.htm

Have you done a visual inspection of the motherboard and the cards? You may spot a faulty tantalum capacitor, if the capacitor shows visible indication of failure.

Otherwise, because the 5155 contains an early 5160 motherboard, the diagnostic procedure at the following page applies:
http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm
 
220V to 110V power adapters are cheap enough ($10 - $15) that if you do find that 220V in not working you could run it through one of those.
 
220V to 110V power adapters are cheap enough ($10 - $15) that if you do find that 220V in not working you could run it through one of those.
Any 220VAC to 115VAC down-converter device (e.g. a transformer) would need to be adequately power rated in order to handle the load presented by the 5155.
The 5155 power supply is rated at 114W, and so assuming a fully optioned 5155, then a down-converter rated at 114W or more is required.
A 100W device might suffice in the OP's case, but if was me buying a transformer, I'd be buying a 150W one.
 
Hello again,

I have finally found some time to open up the computer and see what was wrong. As it turns out, during shipping, one of the power connectors got unseated from the motherboard enough for it not to want to boot, yet not to be visible. I re-seated the power connectors after measuring for any shorts, which i did not find. Ever since, the system has been working fine under 220V again.

Thank you for your help.
 
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