This is a Hickok 534 that I repaired and calibrated for a Customer. The Customer asked me to wire a Bias fuse bulb and test points for checking plate current.
The Hickok 534 has a built in multi-tester with VOM capability. This model has a common failure in the multi-tester circuit that switches the meter from tube testing to multi-meter testing that causes the meter to not operate when testing tubes.
The plate current test points have a precision resistor so a millivolt meter can be installed to measure the voltage across the resistor that is proportional to the current in the plate circuit. A current meter is not required to measure the plate current and a jumper is not required to test tubes when not measuring plate current.
It is a good idea to install a Bias fuse bulb in tube testers that don’t have a fuse bulb. Over current through the Bias pot can cause damage and there are no replacements available for the custom wire wound Bias pot.
Just curious how you got the surface so shiny. And…do you repair and calibrate Jackson 648? If so, how much? Thank you!
I didn’t do any cleaning of the deck. It came to me from the Customer looking like that. Contact me through the contact form and we can discuss your Jackson 648.
I have a TV-3A that has a similiar problem, the bias mMho’s adjustment is off causing meter reading to be very low, not reaching the tube test side of the scale, are the 534 and TV-3 related in a similar way. Just scratching my head red and losing hair.
They both use the Hickok mutual conductance circuitry. Your TV-3A probably needs to be checked and calibrated.