Calibration on common multimeters?

[retiredcaps]

Those are excellent "see through" photos.  Mirroring and flipped over helps a lot.

Here are some thoughts and suggestions.  Bear in mind, I'm still a newbie in many ways and learning about how a rotary switch works is one of them.

I circled in blue what I think are the three solder joints for each of the three pots.  Please verify.

In yellow, I traced out where VR2 goes to in the rotary switch.

In red, I traced out where VR3 goes to in the rotary switch.  For VR3, you might want to verify with continuity that I have mapped this out correctly?

If you read this blog

http://www.righto.com/2013/04/tenma-72-7740-multimeter-review-and.html

you can see how the rotary switch works.

If you can determine the same for the DM-55, then maybe that will tell what VR2 and VR3 do?

[Jidis]

Hey again Retiredcaps,

Thanks! Here are some of the pot traces from the bottom of the board which are blocked by the pots,etc. The stuff in your pictures seems to map correctly as well, and the three pot's pins are correct. I tried to get those two pictures as close as I could to the same size, so I can page up/down in my picture viewer and bounce between them, keeping all the pins aligned. The viewing angle of some of those parts on the outside edge makes them look like their pins are in different spots, but bouncing to the top view can give you a better idea of where they really land.   

Don't spend too much time on this. I've got a feeling it's not a very common meter. BTW, that stuff on the rotary dial in your link is fascinating. I was recently wondering how difficult it would be to "re-case" one of those (gasp) Harbor Freight meters (DT-830x) and do a PIC app to use individual pushbuttons for selection, but then got to thinking it would require a bunch of relays or something to replace the dial. I'm not sure people actually determined what the processor was in those either, but the meter itself is all over everywhere.

Take Care

<EDIT>- I forgot- that center pin of VR1 (middle pot) has a solder blob right next to it in those shots. It looks like a pin, but it's nothing.