Hickok 6000a meter issue
 

I got a hickok 6000a that works for the most part. but the meter i think is bad.

Its supposed to be a 100ua meter, but it is taking 342ua to deflect the meter fully.

Because of this, its throwing everything off. cant bring line test into calibration, all micromhos readings are super low, the list goes on.

Any way to recalibrate for this high of a uA? or where to obtain a replacement meter?

Just a couple thoughts (Am not real familiar with this piece):
Is the movement sticky?
Is there an internal adjustment for the movement? Or the circuit?
Change/add a shunt resistor?
I just fixed a Simpson 260 Series 4 that was like that. Needed a new meter. Took more of everything to deflect it fully.

its the same issue.

no sticky, just something wrong wtih the meter itself.

One guy quoted me $250 for a meter!! id rather junk it before i pay that.

Almost need a linear transistor amplifier to get this thing to operate correctly on its original meter, or a simple op-amp circuit to increase the meter gain to 340ua.

$250! Tell him you'll sell him a "holder" for his meter for $500! If your SURE it's the meter, and it can't be disassembled to be looked at, you'll need a new one. You could put a different meter in it of 100ua, and keep looking for a correct replacement. Just "reference" the new one to the original. Keep us informed!

I have seen somewhat similar things with very old meters. It seems the magnets lose their strength over so many years. I think the only options are to recharge the magnet or replace the unit. Well, you can get fancy I suppose and build a little amplifier to convert 100 microamperes to 400 or so. A current gain of 4 is easy, and the unit can be powered with a lithium cell or a couple of alkalines.

The magnetic flux probably decreases exponentially with time, meaning that the change is slowing down and it probably will be consistent for quite a while.

One more option is to recalibrate the scale and only use the first quarter of the pointer travel.

yea i dissasembled the meter, nothing there except a spring, coil and a BIG magnet.

Don't mess with it too much-I'm 50/50 fixing movements. You may want to apply current to it and watch the mechanics of it.

I have, its perfectly linear.

342ua for full-scale yet?

yup. 342uA for full scale. and no jerkyness.

He came and picked his tester back up yesterday. i told him there was nothign I can do. i think he trashed it.