Recurring Power Supply Failure

triley · January 30, 2018, 04:21:AM

Hello Roundtable,
Guys I have a newer pacific hydraulic press with NC style controls. I have a recurring power supply failure and i'm looking for some advice.

It is a 3.5 amp 24VDC power supply. Fuse didn't blow the on the original supply. So I assumed it gave up and ordered another one. Turns out about two weeks later same problem came back, no 24V again.

I checked the power supply and found a good fuse but no output again. I thought they maybe sent me a bad one and I made the mistake of ordering another one and same thing happened. 3rd one has failed and i don't understand if it's not being overloaded what could be going on...

Any thoughts on my recurring power supply failure?

Triley

floridadoug · January 30, 2018, 04:59:AM

I'll assume you've checked the current draw on the output and the fuse you also checked for proper sizing. ?? these would be the first steps in identifying a recurring blown power supply.

triley · January 30, 2018, 08:44:PM

The fuse was original as far as I know. The new power supplies both came with 4 amp mdl glass fuses so I am assuming that is the proper sizing. As for amps, i didn't bother checking because the fuses didn't blow.

floridadoug · January 31, 2018, 03:56:AM

This shouldn't be hard to nail down, how about the incoming voltage, did you check and see if it is within spec? I'm assuming it is 120VAC. You can do this without replacing it again.

But I do think you'll need to put another power supply in place in order to do some real time monitoring. I would replace it and check incoming and outgoing voltages making sure they are accurate.

triley · February 02, 2018, 03:50:AM

What kind of fuse should I use in a DC power supply? When you buy these new, are you suppose to fuse them yourself based on load?

I am going to replace it again and check both incoming an outgoing voltages, infeed current and outfeed current so I have all the bases covered.

floridadoug · February 02, 2018, 03:22:PM

It should be fused properly when you buy it. You'll find your problem once you have verified input and output voltages and currents. (or infeed and outfeed voltages and currents)

triley · February 04, 2018, 06:06:AM

OK, all the measurements look OK, 120VAC In 24.8VDC out. Currents are well within spec only around 2.5 amps DC on the out put side with the machine running.

I stumbled on something else though, the temperature of the cabinet. i noticed that it has been hot in there recently but think think much of it. There are two cooling fans to circulate air in the cabinet, both are not working. Turned out one fan had seized and tripped a breaker. I disconnected the bad fan reset the breaker and now at least one fan is working while I order another one. Now I'm thinking that the cabinet temperature has something to do with component failure. I'll know more this week after the machine has been running for a while.

floridadoug · February 05, 2018, 03:59:AM

I love it when a plan comes together.... That's making more sense now.

EltonMos · February 13, 2018, 08:09:AM

Quote from: triley on February 04, 2018, 06:06:AM
OK, all the measurements look OK, 120VAC In 24.8VDC out. Currents are well within spec only around 2.5 amps DC on the out put side with the machine running.

This very well may be true. I've heard that high temperatures can do that. I'm really interested to find out what was the cause of all this so please keep us posted, Triley.

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Recurring Power Supply Failure