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Power Supply Testing 5150

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Dec 6, 2009
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Hi all, I have a power supply from an 5150 and It won't stay on for then a few milli-sounds enough to slightly spin the fan, then it's dead. I have removed the power supply and tested it with known good system and with no system and with a load like and HDD still nothing so the fault is inside the power supply itself. I don't know if this means anything but I toke the voltage readings from the molex plug and the 5 volt jumped right up to the normal range however the 12 volt did not so well so I am thinking its in the 12 side of the supply unit. I have just a muilt-meter for testing so please try to give simple step by step help. Thanks and have a nice day.

Note the caps look good, no pop tops or anything like that, nothing looks burt or shorted.
 

modem7

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Then I have the schematic diagram. I'll scan it then post it. It will be useful for others contributing to this thread.

Regarding the 12 volt line not rising like the 5 volt one. Was that the +12 volt or the -12 volt line, or both? Could be a red herring, but worth investigating.
 
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That's looks really hard, I have no ideal what that means or how to read it. It was the +12 becuse it was molex 4 pin plug.

Then I have the schematic diagram. I'll scan it then post it. It will be useful for others contributing to this thread.

Regarding the 12 volt line not rising like the 5 volt one. Was that the +12 volt or the -12 volt line, or both? Could be a red herring, but worth investigating.

 

nige the hippy

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first check c33 isn't shorted, then check CR9 is a diode & not a piece of wire (electrically speaking)!

And (as usual) beware, this thing can kill you, even when switched off!

If you have the pcb exposed, give it 2 or 3 minutes to discharge after switching off then short out the big reservoir caps with a meaty old screwdriver
 
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Hi, both those parts give me numbers on the continuity test so I guess that means thay are good and not shorted. Thanks

The supply has been unplugged for a month or more now.




first check c33 isn't shorted, then check CR9 is a diode & not a piece of wire (electrically speaking)!

And (as usual) beware, this thing can kill you, even when switched off!

If you have the pcb exposed, give it 2 or 3 minutes to discharge after switching off then short out the big reservoir caps with a meaty old screwdriver
 

Chuck(G)

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The +12V thing may be a red herring--the PSU is designed so that -5 and -12 and +5 appear first, then +12 (not doing this can damage devices).

Have you performed a continuity test with the PSU completely disconnected (and power off) of all of the outputs to ground to see if one isn't shorted (i.e. possible bad capacitor or transistor)? The output circuitry on the PSU isn't terribly complicated (assuming that this is the correct model--there were several designs used for the 5150--mine, for example, had an AC fan).
 
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Hi, I tested all of the wires and I don't find anything that has an open short. Anyone have anymore ideals? Thanks and have a nice day!

Edit: Just for the hell of it, I tested a run of the mill AT PSU, the numbers are much lower and do not keep going up till it reads unlimited.


The +12V thing may be a red herring--the PSU is designed so that -5 and -12 and +5 appear first, then +12 (not doing this can damage devices).

Have you performed a continuity test with the PSU completely disconnected (and power off) of all of the outputs to ground to see if one isn't shorted (i.e. possible bad capacitor or transistor)? The output circuitry on the PSU isn't terribly complicated (assuming that this is the correct model--there were several designs used for the 5150--mine, for example, had an AC fan).
 

Lorne

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Not to muddy the waters of this thread, but I'm watching this post with interest.

I have a PSU (suposed to have been NOS) for a 5150 (or 5160) that I believe has the exact same problem. It was made in Mexico, IBM P.N. 6447192, 130 watts output.

When I flick the power switch, the fan spins for maybe a half a revolution. The +5V jumps on my volt meter to 5V and then slowly drops to zero as the power disappears (almost as though something is discharging). The 12V jumps to 2V and then drops to zero.
If I flick the switch on and off several times in a row, the fan doesn't spin. If I wait a minute before turning it on again, the fan again spins for a split second.

ruthlessperson: is your PSU doing exactly the same thing?
 
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Lorne yes that is the same thing mine is doing same thing to the "T" . This is a 2nd 5150 PSU unit that I have seen do this. Now yours makes a third, maybe if we all can troubleshoot and solve this we can find a common problem point in these PSU's, and have much more easy fix down the road. Did yours pass all the checks listed in this post so far?


Not to muddy the waters of this thread, but I'm watching this post with interest.

I have a PSU (suposed to have been NOS) for a 5150 (or 5160) that I believe has the exact same problem. It was made in Mexico, IBM P.N. 6447192, 130 watts output.

When I flick the power switch, the fan spins for maybe a half a revolution. The +5V jumps on my volt meter to 5V and then slowly drops to zero as the power disappears (almost as though something is discharging). The 12V jumps to 2V and then drops to zero.
If I flick the switch on and off several times in a row, the fan doesn't spin. If I wait a minute before turning it on again, the fan again spins for a split second.

ruthlessperson: is your PSU doing exactly the same thing?
 

Lorne

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I haven't done those checks yet, but I will, and I'll let you know what happens.

Something else came to mind.
Way back in April/09, patscc (I don't know what's happened to him - must be hanging out with Terry Yager) had a problem with a Heathkit H8 not working.
He solved the problem fairly quickly.
His fuse in the PSU was OK, there just wasn't any AC power getting to the PSU.
Turns out his on-off switch wasn't on-ing.
His volt meter read open in each position.
He saturated the switch with contact cleaner and it worked.
He said it was another case of grease gone bad.

So I'm wondering, could it be something wrong with our on-off switches?
They make contact for a split second, and then contact is broken?
Just a thought.
 
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Lorne, that's what the problem with mine was I check the reading with the swtich open and closed both showed unlimited number. So I rocked the switch back and forth for about a min really fast. Toke the reading again and it showed 0 in the on and unlimited in the off. So I hooked up the PSU to two drives hit the swtich and it came to life.




I haven't done those checks yet, but I will, and I'll let you know what happens.

Something else came to mind.
Way back in April/09, patscc (I don't know what's happened to him - must be hanging out with Terry Yager) had a problem with a Heathkit H8 not working.
He solved the problem fairly quickly.
His fuse in the PSU was OK, there just wasn't any AC power getting to the PSU.
Turns out his on-off switch wasn't on-ing.
His volt meter read open in each position.
He saturated the switch with contact cleaner and it worked.
He said it was another case of grease gone bad.

So I'm wondering, could it be something wrong with our on-off switches?
They make contact for a split second, and then contact is broken?
Just a thought.
 
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Yes that was it... that's all I had to do to fixed it, rock the swtich back and forth fast for about a min.

Thank you for that and thanks to the others for helping.

Are you saying that was it?
The PSU works now?
It was the switch?
 

Lorne

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OK - I'm going to go try flicking my switch too.

Then I have to remember who the other person was that had this same problem.
Edit: It was dongfeng
 
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Chuck(G)

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I'm glad you got the thing going. Some of us anticipate that you've done the obvious--e.g. check for voltages on the primary side of the PSU, including line filter components, rectifier, fuses, etc.

Perhaps we need to assemble a troubleshooting guide for folks here.
 
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Well I am a total newbie, I think that would be wonderful ideal to make a troubleshooting guide. The only thing I did was narrow it down the PSU it self and the fues looked good, and northing looked burt or poped. After that I was cluess. ;-)


I'm glad you got the thing going. Some of us anticipate that you've done the obvious--e.g. check for voltages on the primary side of the PSU, including line filter components, rectifier, fuses, etc.

Perhaps we need to assemble a troubleshooting guide for folks here.
 

Lorne

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And mine is fine too.
It wasn't the switch though.
I thought it was for a 5150, but it turns out it's for a 5160.
Duh!
No load = no power.
Swapped it out with the PSU in my 5160 so it had a load, and it works fine.
 
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