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Figuring out the output of a power supply

Gargen

Gargen

Golden Member
I have a power supply (not a computer power supply, but rather a part from inside a larger piece of equipment) that produces an unknown voltage and frequency and I'm trying to figure what that output is.

It's possible that frequency and voltage may be as low as the standard 120v/60Hz or as high as in the thousands (at least one of the two would need to be increased a lot, and voltage is almost certainly increased). The total output is probably in the 20w-30w range. There seems to be some kind of serial number on it (9900103144), but it otherwise has no identifying marks.

What's the best way to find out the output of the power supply without buying expensive equipment? Is this something I can take down to a local electrical supply store and have measured?
 
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The best way to figure this out is to know what the PS came out of, and backtrack it that way. Whatever it came out of probably has specs and parts lists. If not, just knowing what it came out of can give you a clue about the PS.
 
First, "power supply" almost always refers to AC input, DC output, so the output wouldn't have a frequency.

But really... you need a multimeter. Every man needs a multimeter.

What is your purpose? To list the specs and sell it?
If you have any purpose in using it, you need a multimeter.
 
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LTC8K6 said:
The best way to figure this out is to know what the PS came out of, and backtrack it that way. Whatever it came out of probably has specs and parts lists. If not, just knowing what it came out of can give you a clue about the PS.
Click to expand...

edro said:
First, "power supply" almost always refers to AC input, DC output, so the output wouldn't have a frequency.

But really... you need a multimeter. Every man needs a multimeter.

What is your purpose? To list the specs and sell it?
If you have any purpose in using it, you need a multimeter.
Click to expand...

It's a part out of a custom piece of electronics (with no markings at all so I can't look up the thing it came out of) that I want to replace. It is AC output and is probably very similar to (and may actually be) a florescent lighting ballast.
 
Take a picture. The voltage rating on the caps on output side give you a decent clue. The rating of the rectifier etc will give you more clues. Depending on the supply you may not be able to just hook it up and test with a meter. There may be loading requirements to actually bring output in to spec. You may need to test with a large megaohm resister.
 
Touching your tongue to the contacts is the best way. I've used this method to test 9V batteries for years, and it should work on anything electrical.
 
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Gargen said:
It's a part out of a custom piece of electronics (with no markings at all so I can't look up the thing it came out of) that I want to replace. It is AC output and is probably very similar to (and may actually be) a florescent lighting ballast.
Click to expand...


I mean... someone made the thing.. I find it really hard to believe that there is no way to track down even a person who worked on it.

In all seriousness, if you don't know how to use a multimeter (and it sounds like you don't) I would find someone with a bit more elec knowledge to help you. If this super secret piece of equipment has a power supply which is so difficult to source then the other bad parts will be impossible to find if you blow them up.
 
wtf application is this? it could be anywhere from 120 to kV AC or DC?

nobody at a local university/store is gonna hook it up to anything unless you tell them what it came out of.
 
Just tell us what you got it out of and what you are trying to do.
Is it a ballast for a light fixture? What type of lamps?

If it is literally a black box with wires on it, you will need an oscilloscope and multimeter to see what the output is.
 
I would start my working my way down. Assume it's high voltage. Put the two probes in a bucket of water. Turn it on. If the water bucket does not explode, and it's just making small bubbles, then it's probably a lower voltage that is safe to use a multimeter with.

Results may vary, and I may not be held responsible for arc flash, water damage, electrocutions, or other damages. 😛
 
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