[Mini Miller]

I just picked up a complete Sola CVDC (constant voltage DC) power supply today from the local surplus place. The part number is 28-1561-2 and it is rated at 48 volts DC @ 10 Amps. It is a rack mount PS from the Telco industry. I was hoping to use the transformer for my CNC mini mill project but I am having trouble finding any useful info about it. It seems to be a very popular power supply but I can't find a wiring diagram online.

When connected to a 122 volt AC input, I get the following on the secondaries:
red wires - 534 volts
yellow wires - 69 volts
green and black/green - 234 volts

I am assuming that I would use the 69 volt secondary but wouldn't that produce over 80 volts when rectified? Also, the 534 volt pair scares the beans out of me. Any help is appreciated.

Thanks,
Jamie

[ViperTX]

Well, I'm not familiar with that unit, but you mentioned Telco....so, I suspect that the 48VDC rating is really the rating for the input, the output depending on whether this was used to power units most likely 120 VAC, or it could have been used to provide a DC to DC conversion which is more typical use.

[Al_The_Man]

AFAIK these are DC supplies if so have you got your meter set to dc and not ac? If this is one of the Sola switching supplies you could be getting strange readings without a load, maybe if you post a photo I would recognize the type.
Al

[Mini Miller]

Hey guys, thanks for the responses. I know that this is an unregulated, not a switching supply. Plus, I took my my measurements from the transformer only, as you can see in the attached pics, it is disassembled. If you have any info on how I night use this thing please let me know.

Thanks,
Jamie

[Al_The_Man]

I guess you have to ask why did someone disassemble it? You are Probably have to get the hook up from sola if they will supply it. The reason you may have got strange voltages is that these operate on a resonant circuit with a large capacitor connected across the ac for regulation, the transformer works in part saturation (high current) at all times so they usually run hot, (hence the vented cover on the txfr).
Al

[tekno]

I have used these in telecom systems. We connect them to small back up battery systems and the power supplys are good for the 48 volts / 10 amps. Im not sure why your getting the strange reading. I have a westcom system in storage that is 120 to 48V /10 amp output. I'll try to remember to take some photos for you..

From what I remember Sola makes the power supplys for many companies that put there name on it..

[Mini Miller]

Update: I forgot to post that the component in this picture was attached to the 2 red leads. That is where I read the 534 volts. Does that help sharpen the picture any? I think I am gonna put the supply back together and see what I get.

Thanks,
Jamie

[Al_The_Man]

From your first post, the red leads are AC so this would probabally be the resonant capacitor for regulation.
Al