BM235 Faulty/variable DC voltage readings

[ClifS]

I have been using this BM235 since 2018, and for my use it has been more than adequate.

I turned it on a couple of days ago and nothing. Checking the batteries, I found they needed to be replaced. There had been some minor leakage, but it didn't go anywhere other than the battery contacts, which I cleaned with electronic cleaner solution and a bit of rubbing(nothing extreme).

When I put in the new batteries and set the meter to DC voltage(auto) it showed 1.5 volts or so, slowly counting down. When I installed the probes and shorted them together the voltage dropped about .05 volts, once again slowly loosing voltage. When I disconnected the probes, the voltage rose back to where it was originally, and slowly counting down.

I cleaned the battery contacts again and also rubbed a pencil eraser on the pcb battery contacts. Putting the unit back together and inserting the batteries, I get the same response but the initial voltage is about .5 to .6 dc and counting down. Response to shorting the probes is the same, about .05 v dc down and slowly counting down. Disconnect the probes and the voltage goes back up to the original voltage, slowly counting down.

Of course DC mV are doing the same thing, but all other features are normal.

All of this appears to be some sort of slow capacitance discharge, but I'm stumped.

Any and all suggestions would be greatly appreciated.

Clif

[J-R]

Is it possible that the batteries or the cleaning solution may have leaked a little onto the PCB?  Maybe pull it apart and inspect everything under magnification.

[shakalnokturn]

Visible or not, your symptoms are typical of a contaminated PCB.
In your case I'd disassemble fully and scrub the PCB in warm water with a toothbrush.

[ClifS]

Thanks for the response guys. The tear down begins this morning. Setting up the microscope.

Any other suggestions folks?

Clif