I was recently asked to repair 3 modular power supplies. I usually mainly work on Audio systems but I do have a reasonable understanding of linear PSU and SMPS design and I have a good amount of general fault finding experience. All of the units were the same model (ACE450F by Cosel). They have 4 otuput rails (5v, 15v, 24v and 48v). Two of the units had no 48v outputs and the third unit was dead altogether. I have managed to get all three units up and running correctly with no loads but now I need to test them under suitable loads. the labels on the unit state that the output power rating is: 400 / 450W MAX and then the individual outputs state the following: 
> 5V  10A
> 15V  20A (27A)
> 24V  6.5A (8A)
> 48V  3.2A (4A)
I'm looking at buying some wire wound load resistors to build a dummy load but I'm a little unsure of what values I should be using.
Can i just calculate resistance using V / I for each output or do I have to calculate the power first? I'm guessing where it says OUTPUT: 400 / 450W MAX is referring to the maximum combined load of all outputs... is this correct?
I understand that I might be completely wrong here so I thoughts it's definitely best I obtained a little advice so as to not blow up the PSU's which I have just spent a day fixing.
Thanks in advance
> 5V  10A
> 15V  20A (27A)
> 24V  6.5A (8A)
> 48V  3.2A (4A)
I'm looking at buying some wire wound load resistors to build a dummy load but I'm a little unsure of what values I should be using.
Can i just calculate resistance using V / I for each output or do I have to calculate the power first? I'm guessing where it says OUTPUT: 400 / 450W MAX is referring to the maximum combined load of all outputs... is this correct?
I understand that I might be completely wrong here so I thoughts it's definitely best I obtained a little advice so as to not blow up the PSU's which I have just spent a day fixing.
Thanks in advance
Attachments

1.5 MB Views: 4