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I received a S1057B test set the other day. I have since replaced all 4 D cell 1.5V batteries in addition to the 1.5V N cell battery in the meter compartment. I still can't get meter setting 4 to allow me to adjust to center scale. I have checked all switch connections for voltage,continuity, and current. I am getting current flow to the + post of the meter when I hook my meter in line. As I adjust the Zero Center Adjustment pot this current varies from around 15uA to around 25uA which would lead me to believe that everything is functioning correctly with that part of the setup as this is a 50uA full scale meter. That would be half scale.
Well the other problem is when I hook the test set up to my Mitrek I can't get a reading in any meter position etc. I can't get a reading of the internal 4 D cell batteries either when I select that metering position. I have checked both meter protection diodes and they show to be good. I do not have a cap checker here at the time (at my girl friends house and I forgot my cap meter ).
So my question is this have I overlooked something or is the meter movement itself bad? Is this a common problem? I hate to know that this unit is in such nice shape and the meter is bad. Anyone know of a reasonable replacement or should I just look for another test set? Thanks ahead of time Shane
My recollection is that you need to check the manufacturing date on the test set.
I fit was made fefore January 1, 1970, it needed to be modified to work with Mitreks (and Micors)
Also look for the number SLN-6056A-4 on the test set cables, and anywhere on the inside of the test set chassis.
If it has that number, its supposed to already have been modified.
In which case, I have no guess why its not working.
Maybe find another Mocom or Micor and see if it works correctly on those.
Check the N-cell battery holder for corroded connections. The circuit is very sensitive to any contact resistance. I have seen the problem where it looks like the battery is getting weak and the zero shifts. You put in a new battery and it drifts off zero again in a few days. You wiggle the battery in the holder and it zeros again. Clean up the contacts and all is well.
As mentioned above, there are modifications on older units required for Micors and Mitreks. I thought I had the mod info somehwere but I can't find it right now.
I guess I should have put in my original posting that the meter does not move at all. It remains on the left side of the meter movement at all times. It does not move when you try to check the voltage of the internal D cell batteries either. Best I can tell the meter will not move at all.. I will clean the contacts tomorrow with some emory cloth and contact cleaner. If it still doesn't work I will post on here for some more ideas.. Thanks for the help thus far guys...
The meter "remains on the left side of the meter movement at all times."
I would say the meter movement is:
1. Jammed or jumped off the jewel bearings.
2. Open coil can test w/ohm meter.
3. metal shavings in air gap between meter movement coil and magnet.
There are two diodes, back to back, accross the meter coil, could be shorted!
Diodes are good checked them first thing.. I have taken meter apart and removed front cover Needle moves freely without binding,etc. So that rules out jumping off etc. When i test the two rear studs marked + and - i get nothing on the ohm meter. I guess the internal coil is open! Blah.. Anyone know of a suitable replacement meter? I don't know of anything else it could be....
Just find and buy a similar sized 50ua meter and remove the face from the old one and put it on the new one, go through and tweak it up and your done.
I did that on an "A" model test set that had a broken meter. I found a panel meter over at http://www.allelectronics.com that was nearly perfect, the case size was just a tiny bit smaller so i just trimmed the face from the old one and put it in the new one.
Have a look on ebay and search for panel meters, plenty of them show up and are a lot cheaper than getting another test set that might have the same problem anyway!
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