Anybody own the MPJA 9616PS / Circuit Specialists CSI3003SM power supply?

[AndyCC]

I bought the MPJA 9616PS power supply about six months ago, and have been very happy with it. The other day, though, I was using it to charge a lead acid battery... and I plugged the battery in backwards. Feeding all that current through the power supply didn't do it any good. It looks like R6 took most of the punishment.

I know there was some discusson on CPF about the MPJA power supplies. Does anyone have a 9616PS, and if so would you mind opening it up and telling me what the value of R6 is?

Based on the lack of debris, I'm tempted to think it's just a jumper rather than a resistor with a nonzero value. But I'm hesitant to just stick a wire in there and power it up.

Some day I'm going to learn about using fuses...

 

[AndyCC]

Today I replaced the existing lead in there (which was 20 gauge wire) with some 22 gauge hookup wire I had on hand. So far so good - the voltage seems close.

I don't think I quite trust the current anymore... at rest the meter's reading about 0.2 A rather than 0. I'm not sure if that has to do with my choice of R6 or with something else I stressed when I pushed 13.8 V through there backwards.

At any rate, I have a power supply again, even if it's a little degraded.

 

[Steve K]

it's a shame that you can't get a schematic for the power supply (I'm assuming that you contacted the manufacturer, right?).
Hard to even guess what might be causing the bad current measurements. You might do a close inspection of the board and look for high resistance connections, damaged parts, etc. If it hasn't caused any damage of significance, then perhaps just run a few tests to see if this is a constant offset of 0.2A, or if there is a gain error too.

I think you were correct to just jumper R6. It's not uncommon for a circuit board to be designed to include certain features, but not actually install those parts for low-cost versions. I've seen lots of parts with zero ohm resistors installed, or nothing installed on the pads (for surface mount components). You might inspect the bottom of the board to see if any connecting traces or parts also suffered damage.

 

[AndyCC]

it's a shame that you can't get a schematic for the power supply (I'm assuming that you contacted the manufacturer, right?).

Unfortunately, I can't even tell who the manufacturer is. Both companies that sell it just re-badge it, I suspect - and there's no identifying marks on the PCBs.

Thanks for your comments. There is a suspiciously bulging capacitor near R6, and I think that's what I'll attack next. It seems like there is gain (it's not just an offset of 0.2A).

Thanks again!