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Any way to replace 5160/5161 power supply?

Trixter

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Chicagoland, Illinois, USA
After 15 years of searching, I'm now the proud owner of a 5161+cards+cable (without emptying my bank account, which is why it took that long). Unfortunately, the 5161 130W power supply is completely dead. I plan on following the procedure at http://www.minuszerodegrees.net/5150_5160/MDC/minimum_diag_config.htm tomorrow night to completely verify this, but there is no activity at all when the switch is flipped, not even a small fan move.

I've spent the last 45 minutes searching the forums for what to do, and all of the (very helpful) advice was for repairing the power supply, and all of that advice strikes fear into my heart. I have never built or repaired anything with a soldering iron, I don't own a multimeter, and even if I did I wouldn't understand how to use it or interpret the results. I feel very helpless in this area. I am knowledgeable in many specific areas of 51xx hardware, but electronics repair is not one of them.

Other than taking a few electronics courses at a local community college, is there any practical (ie. component swap and maybe a few cut/reconnected wires) way for me to fix this situation? Is it possible to replace the power supply completely and not have it look like a complete farce, for example? Or maybe, open it up and throw out everything but the red switch and replace with guts from a $20 new supply?
 
.... Is it possible to replace the power supply completely and not have it look like a complete farce, for example? Or maybe, open it up and throw out everything but the red switch and replace with guts from a $20 new supply?
Yes. Replacement of the power supply on a 5161 is an extremely simple matter. I haven't looked for a new power supply for a 5160 or 5161(I think they are the same) recently, but if you find one, it's very easy. As far as opening the old one and repairing it goes, that would be a little above my skill level, so I won't give you any advice there.
 
You may want to peek inside the PSU just to see if there's a blown fuse (it happens sometimes when the line filter caps go kablooie). A visual inspection won't hurt.
 
Or maybe, open it up and throw out everything but the red switch and replace with guts from a $20 new supply?

This is exactly what I did, and it isn't terribly difficult, though it did require some soldering. I think it was this one that I used and it is still ticking away nicely, though if you start with an AT power supply rather than an ATX I think you'll be able to get away without resoldering the actual power connectors (and therefore without having to test it with a multimeter). I'm pretty sure the big red switch is soldered on though so you won't be able to get away without soldering altogether.

The board of the replacement PSU I used was smaller than the XT PSU's board and the mounting holes didn't match up so I screwed in one corner and just used some plastic spacers I found in my junk box to stop the board moving around and shorting against the case.
 
A bad capacitor on the motherboard (C32?) can give the effect of a bad PSU.

The 5161 doesn't really have much of a motherboard. It's just a clock generator, a bus and the PSU. Everything else is cards plugged into the bus.

Some time ago I had a similar situation, and then it was the line filter cap on the 12V line that had gone. It should be obvious if something similar has happened, and as mentioned; it's worth having a look inside the PSU.

Otherwise, an alternative if the PSU is totally dead, is to replace the contnent with the contnents of a generic AT-style psu. Just make sure to discharge the caps before you start moving the cirquit boards around.
 
I have done it with ATX before.

- ATX to AT power adaptor - or cut/resolder lines off a dead PSU
- connect the switch output to the PSU input (make a plug adapter or join the two sets of wires + heatshrink)
- make sure the board is earthed (metal to metal may not happen if you make an adaptor)
- make sure green power-up line is connected to ground
- remove unneeded lines like 3.3V
- make an adaptor board out of plastic, perspex, or wood or something
- join the fan wires to the old fan

I prefer to do this than to sacrifice another AT supply (which are rare enough) when we have so many ATX units going to the tip.

(This doesn't replace any of the good/better advice posted above, just passing it on in case it helps)
 
I do not own a 5161 so never looked insise one, are the power supplys the same as in a 5160 or even a 5150, but less wattage?
 
Thanks so much for the words of encouragement. I agree that I can at least open it up to check, so I proceeded to do that this evening. (In moving the hard drives forward to get the power supply to "unhook" and come out, I couldn't move one of the drives more than 1cm even though there were no screws holding it in any more -- that was troubling, but I managed to get the power supply out.)

However, in trying to open the PS, I came across two of these:

2013-02-12-21.13.jpg

They look like hex/torx screws except there is a pin in the middle of the depression, preventing me from using my hex wrench to unscrew them. I can't seem to get the two metal halves of the PS apart without undoing these two odd screws.

I've never seen "keyed" torx screws like this before. Are the bits for these easy to find? Or should I buy a vicegrip and try to unscrew it by grasping the head?
 
Security Torx. You can get driver bits at your harware store or ebay. Don't use vicegrips it will tear it all up.
 
On the bottom of the case, is there a circular plastic hole? There maybe screws inside there holding the drives in still. That's where I was having issues too.
 
in trying to open the PS, I came across two of these:

That's really bizarre - that can't be stock, surely? I'm not sure when those screws started showing up, but I'd have thought it would be much more recently than they stopped making 5161s. I know the PSU in my 5160 didn't have those, at least, and none of the ATX PSUs I've taken apart had them either. I'm curious about what that PSU is now and why it has such unusually stringent security measures.
 
On late model 5160s, IBM got their PSUs from a number of sources. I've seen the security Torx screws on the 4869 external floppy boxes as well.

Sometimes "tamper-proof" doesn't mean beans, however. Last week I re-LED-ed a bunch of night lights (white LEDs to decrease in brightness as they age--and I'm cheap). All were buttoned up using tri-wing "tamper proof" screws and all could be unscrewed using a plain flat-blade screwdriver.
 
My 5150 and all my 5160 power supplies had at least one of those security screws.
I also find them in Compaq all the time, so generally have the piece ready to go. Any half decent security bit set should have them in a few sizes.

FYI: Those other tiny bolts (8.5mm??) are the same size as the screwdriver fitting, so if you remove your bit, the driver works directly on them (well it did for me, I thought it was pretty sweet)

The infamous line filters can be found on the small circuit board that hangs off the rear of the PSU, they will most likely be torn apart. I'm hoping you find a blown fuse to go with it (although I haven't seen that happen myself, my machines have all powered through the pop, including last weeks IBM 6150! God that gave me the willies)
 
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On the bottom of the case, is there a circular plastic hole? There maybe screws inside there holding the drives in still. That's where I was having issues too.

Sure enough, there is, with one screw! So that's what I was running into. I don't recall seeing this on my other machines, but then again I have probably looked at the bottom of them less times than I have fingers.

I used more-than-usual force trying to get the drive out; I hope I didn't flex the circuit board beyond operational capacity. I think I heard it give a little crackle at one point :-(

I will purchase security torx bits tonight and see what I find.
 
If you lived in Florida, I'd have repaired the PSU for you. I'm quite good with an iron, and a multimeter (though I usually use my oscilloscope so I can check for ripples and stuff.)
 
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