1. Home
  2. Electronics Repair
  3. Power/Mate corp BPA-10E

Power/Mate corp BPA-10E

I have a Power/Mate BPA-10E with issues. It is adjustable from ~2.5VDC to ~13VDC (The panel meter is 0-10VDC, so I assume that that's what it should be adjustable throughout). I'm checking the output with a calibrated Fluke 87, so it's not just that the meter needle is offset or something of that nature. I'm trying to figure out what's going on in the unit. Does anyone happen to have any schematic or service manual for this unit? The unit regulates properly on both current limiting and voltage regulation, but it seems to be offset by ~2.5V. It's possible someone modded the supply to run at 12 or 13V so they could run car equipment or something like that, I don't know the history of the supply, I just don't want to be using it if something's wrong. I suspect that a voltage reference in the regulator circuit has gone high, all I've found are three zeners, two 13V's and one

6.3V, I haven't gotten them off the board to test them yet, and I'm no good at reverse engineering from board to schematic and these zeners might not even be the original parts. Any thoughts on this subject.

(note, how do the "pros" test zeners? I want to see if I test them the same as you guys)

Same song, second verse. This unit has five output transistors (one drive and four outputs, from what I can tell). Their labelling is

QP0010

274 date code

Any idea what these original transistors are? Via diode test they are NPN devices. This supply is 10V 10A, linear, so assuming they dissipate maximum voltage of 10V, maximum current of 2.5A each, they are 25W or so (I know, very brutal calculations, please don't tear me apart for it). Should common new transistors such as 2n3055's or something along that line work? Any idea what the originals are, what their ratings are?

I know the info is vague, but any help is appreciated.

Thanks, Steve

Reply to
sck0006
Loading thread data ...

. .

Steve-

Not being familiar with that power supply, it isn't clear what your problem is. Exactly what is it that is "offset by ~2.5V"? Does the built-in meter read something different from your Fluke? If the panel meter agrees with your Fluke, then it would appear to be working properly.

Power dissipated by the transistors is computed by voltage DROP, not output voltage. Measure the voltage between collector and emitter while the supply is delivering rated current, multiply by rated current and divide by the number of transistors.

It is possible that the maximum current rating only applies at maximum output voltage. I assume you have checked the manufacturer's web site for data.

Without a cross reference to the Power/Mate proprietary part numbers, the best you can do is guess. The 2N3055 is as good a guess as any.

Fred

Reply to
Fred McKenzie

Sorry, didn't mean to be unclear. The panel meter (analog meter) is correct, agrees w/ the fluke. THe voltage at a minimum is about 2.5v, and max is around 12.5V. That's what I meant by the offset, the supply I believe should be adjustable from 0 to 10, not 2.5 to 12.5 (the panel meter is 1-10V). I was trying to be clear that the meter was not the problem, and ended up being more confusing than anything.

Yes, I now realize my errors in the calculation. Funny, that's why I wrote that note about the calculations being brutal, because I knew I was doing something wrong but was too tired to figure it out.

I wasn't able to find specs on the supply anywhere. The only Power/Mate website I could find is

formatting link
which doesn't seem to be the right company, or they switched.

Anyway, thanks for the reply, hope I cleared things up.

I guess I just need to start checking parts on the board, there really aren't that many, and I can just check them all (really efficient...). Should solve the problem. I hope Steve

Reply to
sck0006

Steve-

As far as I can tell, Power Mate Corporation may have been absorbed by another company. They don't seem to be doing business under that name any more. (If you had a 20-year-old Allied catalog, it might have more data.)

I found several of their power supplies for sale at various surplus outlets as well as on eBay.

One BPA-10C was listed on eBay as being 0 - 10 Volts at two amps. With your four output transistors, ten amps might be possible at the higher voltage if the power transformer and rectifiers can handle it. Otherwise, four might be necessary to deliver two amps at minimum voltage since voltage-drop is greater.

Typical power supplies of this class used a uA723 voltage regulator IC to drive the transistors. If yours has an IC, even if it has a proprietary part number, look for typical circuits on a 723 data sheet and see if anything looks familiar.

It is possible that yours is working perfectly, and that your assumption it can be adjusted all the way to zero is incorrect. Being able to adjust it above 10 volts is misleading, since it may not be able to maintain the higher voltage under full load.

Fred

Reply to
Fred McKenzie

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.