Superior TV-11 Tube Tester

[J Luth]

I was just given a Superior TV-11 tube tester. It needs a little work that will not be to bad.
The main problem is the meter adjustment is not working correctly. I opened it up and found that a couple of winding's on the the adjuster are burnt. SCHEMATIC AND PHOTOS ATTACHED.

Would like to know what could be used to replace it?

The schematic shows it as a 250 Ohm but the one installed reads 350 Ohm.

[g1]

I would call that 'line adjust' rather than meter adjust. I doubt it gets used near either end so a 250 or 350 should both work there, the wattage rating would be the important spec.
Is it working aside from those bad spots? And they are right in the area of most use? If so, if it was mine I would swap the wires to the ends around which should move the bad spots to an unused section.

[Enzo]

Agree^^^

Value is not critical. Wattage is though. The 0.27A rating on the part with the 350 ohms leads me to think it is a 25 watt part. It LOOKS like a 25w part.

[J Luth]

G1

It is used to set the meter in the center of it's range. Appears to be in the area of most use.
When turning it to set the meter the needle starts to move up but before it is centered the pot reaches the broken spot. When it's turned past the break, the meter jumps up past the center and I can hear a growl.

Tried the tester without centering the meter with the pot set just before the break. Everything appears to work OK. I haven't checked any of the resistors in the unit. I bet both of the caps in it are bad.

[J Luth]

Wondering if this would work.

https://www.newark.com/ohmite/rhs350...ive_Components

[Enzo]

Should work, yes.

[Mick Bailey]

The tester has a 2-wire mains connection with no earth and no isolation, though.

[J Luth]

Thanks Enzo

[J Luth]

Mick
You are correct

[g1]

One side of the line goes straight to that pot. That's why I call it line adjust. It affects the meter by adjusting the voltage going to the whole unit.
I still say you should swap the end wires around and see if it is still a problem. I think it will work fine that way.

[Helmholtz]

I wouldn't use the thing without an isolating transformer.