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Hickok 6000A tube tester meter fix

Fitzgreen505

Fitzgreen505

Member
So, I was trying to "fix" my Hickok 6000A tube tester and I put a multimeter across the leads of the meter.

Ouch. The meter was exposed to the voltage of the DMM and doesn't work any more. Flips to max with just a tiny bit of AC.

So, I was wondering if anyone knew:
1) a way to fix the meter and make it return to normal?

or, 2) what would be a sane replacement (not the $200 meter) for a the Hickok 6000A meter. The manual says it's a 0-100 microamp, 66K meter. Will anything with those specs work as a replacement?
 
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The meter movement may be okay. Take it out of circuit and put 100uA through it. Maybe 10VDC across 100K with the meter movement in series.
 
Sorry. That was a typo. I just did this with a 100K ohm resister that actually measured 98.6K. I hooked that up to the positive and the negative to the negative and ran 9.68 V. However, I wasn't sure how long I needed to run it to affect the meter. At any rate, for the short but measureable 9.86V, the meter behavior didn't change. I assume I'm doing it wrong.
 
Fitzgreen505 said:
At any rate, for the short but measureable 9.86V, the meter behavior didn't change. I assume I'm doing it wrong.
Click to expand...
So you're saying that the pointer slams against the peg with less than 100uA flowing through the coil? Did you try a lower voltage or bigger resistance?
 
Thnks very much for help.
Question 1. Yes. It slams against the peg at less than 100uA.
Question 2. No, I haven't tried to change the voltage or resistance. But I will try that.
For how long does the current have to through the meter?
 
We're not trying to rejuvenate the meter, just trying to prove it's good or bad. Apparently it's not a 100uA meter -- maybe 50uA?
 
It's 1165Ω / 100μA...

I have a dead one that I've been trying to replace for a back-up tester. 58.25mV should give you half scale.
 
Thnks very much for help.
Question 1. Yes. It slams against the peg at less than 100uA.
Question 2. No, I haven't tried to change the voltage or resistance. But I will try that.
For how long does the current have to through the meter?
 
When I pass 50 uA through the meter (5VDC through a 100 Kohm resistor), the meter goes to the 1/2 position (Line adjust). Raising the voltage also increased the meter. I tested it through a 270K resistor and at 5V, it was showing about 1/4 position. So, I think the meter is still good.
Now, I'm just trying to figure out how make the meter work in the tester circuit.
 
I suspect few of us have ever dealt with an issue like this. It's going to be a huge pain to track the meter connections through all of that switchgear. Maybe you could start by protecting the meter (and C9) with a large series resistance, so you can bring AC line voltage up to normal, and then attempt to collect clues by trying various operating modes. You might also poke around for abnormalities with a multimeter.
 
I can't figure out what in the world you might have done with the multimeter to cause this behavior, unless you inadvertently shorted something.

Do you have the schematic for the 6000A?
 
Alan Douglas wrote a book "Tube Testers and Classic Electronic Test Gear", available from Amazon.
Maybe it's worth $30 to see if it points you in the right direction.
Morgan Jone's wrote a section about meters in his book "Building Valve Amplifiers". It's been awhile, but I thought there was a section about determining a meter's sensitivity there.
I have a different Hickok tester, and it's tricky-there's a movable shield around the meter that affects the readings.
Good luck
 
Thanks. Yes. I have the schematic. I think I inadvertently applied voltage across the terminals by trying measure the impedance. It must have affected the coil.
 
Fitzgreen505 said:
Thanks. Yes. I have the schematic. I think I inadvertently applied voltage across the terminals by trying measure the impedance. It must have affected the coil.
Click to expand...

The results you're getting - centered needle at 50uA - would indicate that the meter coil is OK.
 
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