Impedance of a degaussing coil?

[Jon1967us]

The reason why I ask is because the thermal control over the degauss function in a set that I was working on is a bit different than most I've encountered.

The backstory is I had a symptom on an Admiral color portable hybrid where rolling partially colored bars were visible. I determined that after start up, AC current continued to leak into the degaussing coils. This sometimes happens if you put the wrong thermistor in a conventional circuit.

This set uses an unusual "thermal switch" which from the outside looks like a conventional circuit breaker. The filament section of the power supply is tapped and run into this switch, which apparently heats up a resistive element to close the switch, thus turning off the degauss.

The switch wasn't "closing" entirely and so the degauss continued to be energized, thus producing the rolling color bars.

Once the switch was bypassed/shorted and made permanently closed, the symptom went away. At first I thought simply unplugging the degaussing coils would fix the problem, but this smoked the resistor R254, due to too much current flowing through it and the thermal switch not closing sufficiently.

Long story short, I was interested in the impedance of the degaussing coils as a way to figure out how much current it takes off that resistor as the thermal switch tries to close. Also, as a way of determining a possible appropriate thermistor replacement.



Haven't had any success finding a replacement for this littelfuse part so far. So far just shorting the thermal switch seems to be working fine, but the downside is the degaussing is disabled. I may just need to pull the switch, open it and perhaps it's just oxidized, has carbon buildup or something.