Siemens Multizet A1000 Analog Multimeter Calibration help

[Francenthusiast]

Hi !

I am now owner of that 1983 german beauty (a Siemens Multizet A1000) and I seems that it's not calibrated (not zeroing when shorted in ohm range, not 0V when shorted in volt ranges, etc)
The problem is that I have no manual (RTFM will not work this time), I search over internet but no luck...

I guess that I have to play with the two buttons "M" and "E" which I already did, but both of them modify calibration... (And I mean by that it would have been easy if one potentiometer was of ohm ranges and the other for volts but nothing easy here.)

My questions are: can someone knows how to calibrate it (the procedure) ? Do someone have a operator manual ? 

Thanks in advance !

[Francenthusiast]

Sorry to revive this thread, it's just to try a last time to ask if any good soul can help me
Thanks again !

[branadic]

Could it be possible that one is for zero and the other for full scale?
E and M is nothing I'm familiar with.

[Francenthusiast]

Maybe... Both E and M change the reading no matter where I put the selector knob.
Does E and M evoke something to you in german ?

[JS]

  I'd guess the same, one for max, one for zero. Even if that's way out of specs, do the measurements make any sense? measure 10V source, does it say something within one or two volts or it goes crazy? Same for ohms, etc. Worst case maybe 20%+20% of the range, would make me think it could be calibrated, if it measures 1V when you put 10V it's probably something else.

  Nice pics, that's by far the most complicated analog meter I've seen inside, that's a lot of 4k logic to be called analog anyway...

JS

[Francenthusiast]

Thanky you JS, that's the informations I was looking for !
Google translate says to me that "calibration" is "Eichung" in german, so maybe "M" stands for "Maximum"...
After 2 long hours playing with it, I have roughly calibrated I think... (since I don't have the official procedure, I can't definitely say that it is): I first used a small cable to short the two plugs and adjusted "E" to zero on the one ohm range, then still shorted I adjusted "M" on µA rangeto get zero, then back on ohm range and repeat the procedure to readjust it precisely. It gives good ohms and amps reading, no matter the scale but the voltage is a bit off but not by very much (9.6VDC for 9.79V, 227VAC for 234...)
I think it'll be more than enough !

[HighVoltage]

M stands for Mechanik = mechanical zero adjustment, this is for the analog mechanical dial only

E most likely stands for Elektrisch = Electrical adjustment, most likely for the OHM zero point

All these old meters had a mechanical dial adjustment and and electrical ohm adjustment.

Your calibration adjustment is done from the other side, with some potentiometers on the PCB

[Francenthusiast]

Oh ! I didn't even thought about removing the label to see what's under ! Thanks a lot HighVoltage !

So is the right procedure is:
- ohms range, Positive and Ground shorted: tweak "M" to zero
- voltage range, plugged on known voltage battery: tweak "E" to the good value.
Am I good ?

[JS]

  In analog meters the mechanical zero is usually calibrated before each use, depending on the precision of the measurement. If you are trying to measure a low value in a given scale is quite important to do so. Note that for resistance you would be considering the resistance of the leads and all around so won't be true zero while for voltage or current it will be much closer (just noise), so when measuring low resistance values you usually set zero  and then measure, then zero back in the voltage range.

  For the electrical calibration, would do the job for the gain, or max, range, etc. Again, if you are trying to measure a given value and you have a similar reference you could calibrate right before with that reference to use the instrument to make the transfer.

  Now days it doesn't make much sense doing that, when using analog meters you are not expecting to get a highly accurate or precise value (usually) but take advantage of the continuity of the measurement. One application where a DMM can beat an analog is checking a potentiometer, if it has some problem in the trace you'll see the needle dancing instead of going smoothly in one direction as you move the wiper, in that case the calibration is not important. Some people like to do quick checks with analog meters, then again, you're not looking for 0.5% measurements. For those applications when you see the meter is not making much sense you check the calibration.

JS

[Francenthusiast]

using analog meters you are not expecting to get a highly accurate or precise value

Yes I knew it, back in the days in was a pain in the ass even if parallax is precise but anyway, I want to use it just from times to times and also because I love electronics ! Maybe some hype got me

Thank you so much everybody !

[JS]

  I know, I have a REALLY cheap one, REALLY cheap! just to use in case of emergency, or for that pot checking and that kind of stuff. Few weeks ago I crossed one for $15 (much more expensive than the cheap one) and I was tempted to buy it, it had center zero for few ranges (Ithing it was 2 voltage ranges) but even the smallest voltage rating was too high for any standalone zero detector use.

JS