Multimeter always OL

[AcM]

Hi all,

I've a multimeter Vemer VE8020, it's based on the tc820clw ic.
Suddenly in all selector position it shows on the display OL.
No burned components or visible damage, as the issue affects all the measurements, I'm focused on the reference or maybe I'm wrong, I noticed that never changes the value changing the range.
Any idea o suggestion?

Regards

[markusdd]

as an idea: could also be of mechanical nature, i.e. cracked solder joint(s) somewhere, as there is a whole lot of THT components I think this would be worth a look.

also, the big fuse holder also looks a bit unhappy/corroded, maybe it's just a contact problem there?

[Jwillis]

Could be  probe leads have break in wires. Set multi meter to continuity and plugged one probe lead into a port and probe the other port. Repeat with the other probe. 

[DaJMasta]

Just to be sure, you've checked the battery too, right?

[AcM]

Hi all,

thanks for the reply, battery is ok and also the leads are ok.
I went through all the solder joints but nothing changed.

Any other hints?

[rsjsouza]

If it shows OL on volts and current, then any issues on the input circuit can be ruled out - after all, disconnects and bad contacts would show instead "0" (zero).

My suspicion would be something on the upper digital side of the equipment, more specifically in the Vin pins of the TC820 (datasheet is available). I would start measuring the input voltage across both pins and see if it is too high (the datasheet would give additional info, but it is probably 200mV) and measure backawrds from that point in case the voltage is indeed too high.

In case the voltage on the ddvice is zero, then I would suspect the TC820 is damaged.

Good luck in your repair