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tempest
June 22nd, 2016, 04:10 PM
The power supply in my 5150 makes a 'whining' sound when I turn it on. Eventually after a few minutes it goes away, but I'm wondering if this is a sign that it's dying. I've cleaned it out and there's no dust or gunk on the fan blade, but I wonder if it needs to be lubed or something.

mlaferriere
June 22nd, 2016, 04:16 PM
Does the pitch or volume change if you unplug the motherboard and just leave a minimal load on it, say the two floppy drives?

Stone
June 22nd, 2016, 04:19 PM
Does the pitch or volume change if you unplug the motherboard and just leave a minimal load on it, say the two floppy drives?I seriously doubt the load has any affect whatsoever on the PSU's fan speed. It just loosens up with a little running time.

tempest
June 22nd, 2016, 04:29 PM
I've noticed it change with the disk drive is accessed after the memory test.

So it's the fan then?

Chuck(G)
June 22nd, 2016, 04:58 PM
Do you have the black 62.5 watt power supply with the AC fan? That shouldn't be affected at all by load.

Most likely, it's probably a loose core in the transformer. Although the PSU switches at an ultrasonic rate, sometimes harmonics can cause audible vibrations.

tempest
June 22nd, 2016, 05:31 PM
It's a silver (well metal colored) 63.5W power supply. I assume this is the original one.

As long as it's nothing serious I can live with it. Repairing power supplies is well beyond my abilities.

mlaferriere
June 22nd, 2016, 05:46 PM
I seriously doubt the load has any affect whatsoever on the PSU's fan speed. It just loosens up with a little running time.

I was thinking more of the whine caused by excessive or out of spec load on the power supply as opposed to fan noise. If it is just fan noise I apologize for the post but at least that would be an easier fix. :-)

http://superuser.com/questions/832480/why-do-some-ac-adapters-and-power-supplies-generate-a-whining-noise-and-what-ca

I have an 5160 XT board with a shorted cap that makes the PSU whine that sounds like a cricket when I power it on. I could YouTube a video of it if anyone is curious. One of the 12V caps is shorted on my MB.

retrogear
June 22nd, 2016, 06:13 PM
Capacitors as they weaken cause an increase in AC energy in the transformer which creates an audble noise.
The noise will vary in frequency with load because that's how a SMPS regulates itself. AC energy generates more heat internally
because of the power efficiency loss so will degrade slowly over time.

tempest
June 22nd, 2016, 07:59 PM
I can make a recording of the sound if it will help.

GiGaBiTe
June 22nd, 2016, 08:19 PM
Capacitors as they weaken cause an increase in AC energy in the transformer which creates an audble noise.

No, this is not what a worn out / failed capacitor does.

A capacitor can maintain or exceed its rated capacitance to the end of its useful life and beyond.

What causes the chain of destruction in-circuit with the failing capacitor is the fact the capacitor starts leaking DC across the anode/cathode. This voltage causes other components to run out of spec, generate tons of heat and eventually turn into a charcoal briquette or blow up.

Chuck(G)
June 22nd, 2016, 10:09 PM
It's a silver (well metal colored) 63.5W power supply. I assume this is the original one.

As long as it's nothing serious I can live with it. Repairing power supplies is well beyond my abilities.

I don't know when IBM switched from the black PSU with AC fan to ones with a DC fan. My 16-64K 5150 had the black one.

Personally, unless it's very loud, I wouldn't tinker with it, particularly if you don't have any experience troubleshooting or repairing power supplies.

Malc
June 22nd, 2016, 11:15 PM
I don't know when IBM switched from the black PSU with AC fan to ones with a DC fan. My 16-64K 5150 had the black one.

I don't either, Though i don't remember having / seeing an original 63.5W 5150 PSU with a DC fan, My late model 5150 with original 63.5W PSU has an AC fan as does a couple of spare's i have.

retrogear
June 23rd, 2016, 03:18 AM
Sorry GiGaBiTe, I beg to differ. I had serviced various SMPS at component level for 20 years. I've seen open capacitors cause the strangest sounds out of the transformer, even sounding like sizzling bacon in a frying pan.

Tempest, you could try sharing a recording but not sure if anything would be audible outside of the fan noise

tempest
June 23rd, 2016, 05:13 AM
I'll try and get a recording tomorrow.

I don't think this is fan noise. I'm used to old fans and squeaky fans, this sounds more 'electrical' to me.

Stone
June 23rd, 2016, 05:44 AM
The power supply in my 5150 makes a 'whining' sound when I turn it on. Eventually after a few minutes it goes away,...This is a classic description of an old fan (or motor) warming up.

tempest
June 23rd, 2016, 07:11 AM
This is a classic description of an old fan (or motor) warming up.

I hope so. I just want to make sure there's nothing wrong with it.

Also, I forgot to mention that I currently have the case off. I'm sure it will be a lot less audible once I put it back on.

Chuck(G)
June 23rd, 2016, 07:21 AM
Try blocking the fan from rotating temporarily by inserting something that interferes with rotation. For the very short time that you perform the test, it won't hurt the PSU or the fan. You should have your answer in 10 seconds or less.

tempest
June 23rd, 2016, 11:50 AM
Try blocking the fan from rotating temporarily by inserting something that interferes with rotation. For the very short time that you perform the test, it won't hurt the PSU or the fan. You should have your answer in 10 seconds or less.

That's a good idea. I'll give that a try.

tempest
June 23rd, 2016, 05:41 PM
When I blocked the fan the whine really dropped (still there a little but a lot quieter). I guess it is just the fan. Does it need to lubed or something?

Stone
June 23rd, 2016, 05:44 PM
No, it needs to be replaced.

tempest
June 23rd, 2016, 07:02 PM
Can you just replace the fan or does the whole power supply need to be replaced?

Chuck(G)
June 23rd, 2016, 07:14 PM
You can replace just the fan, but you'll have to open the PSU to see what kind you have (and its dimensions).

tempest
June 24th, 2016, 05:13 AM
We'll see how adventurous I feel. If it's not causing any problems then I really dont mind the noise.

Stone
June 24th, 2016, 05:20 AM
If the noise suddenly stops it could be that the fan has seized.