Metex DMM calibration manual

[IvoS]

I am trying to find calibration manual for this Metex DMM M-3270. This multimeter is (I guess) 14 years old but I love it so much, the rotary switch click feel is best out there. There are 4 trim pots on the board plus one trim pot under the LCD, I have no idea which trim pot to turn for voltage, resistance etc. adjustments.
 Any ideas?

[alm]

You could try to find out if Conrad rebranded it at some point, they sometimes have schematics and calibration instructions available. They have sold a bunch of Metex products under their own brand 'Voltcraft'. I believe these days it tends to be Uni-T. Once you've found an article number, you should be able to find the manual on the English or German website. Their German website is the oldest and usually the most complete.

Failing this, the only option I see is trial and error. Only four trimmers, and a limited number of options. My guess is one for DC voltage gain, one for AC voltage gain, maybe one for DC offset or for the lowest DC range.

[grenert]

Many years ago Radio Shack sold some rebranded Metex meters.  Perhaps you might find one that looks like yours and has a manual available.

[retiredcaps]

Schmatic for your multimeter is at

http://elektrotanya.com/metex_m3270_multimeter_sch.pdf/download.html

[IvoS]

Thanks very much.

[retiredcaps]

Let us know which VR controls what.  My schematic reading skills are terrible.

[IvoS]

Finally had some time to play with my old METEX meter. I adjusted everything except current, there is no adjustment trimpot on the PCB. I would have to grind off the shunt or change resistors around it. Another trimpot VR1 is under the display which makes it inaccessible to turn with display in place.