Chassis KCS126A. When I turn on the TV, the thermistor glows for a second or two along the disk edge...just in one pinpoint spot. Then it disappears. RCA part number is 107191 and it's 120 ohms cold. If I take it out and put in a 8 ohm resistor and always bring the TV up on a Variac, would I be hurting the set? The cold resistance on it now is around 8 ohms.

If you always use a Variac, you don't need a resistor at all. Just put an AC voltmeter
on the 6.3 volt filament line and see what setting you need on the variac to get
6.3 volts when warmed up.

The most likely use is to ramp up voltage from a cold start.
On turn on the thermister starts at 120 ohms & quickly goes to near zero ohms.
This limits the surge of the PS electrolytic caps charging up.
Most sets use a @5.6 5Watt FUSE resistor for this.
Test is to jump it & bring up on variac.This is NOT a fix but lets you
check the set out BEFORE you chase & spend $$ on parts.
Thats probably what you have ( without seeing schematic ).

73 Zeno:smoke:
LFOD !

The most likely use is to ramp up voltage from a cold start.
On turn on the thermister starts at 120 ohms & quickly goes to near zero ohms.
This limits the surge of the PS electrolytic caps charging up.
Most sets use a @5.6 5Watt FUSE resistor for this.
Test is to jump it & bring up on variac.This is NOT a fix but lets you
check the set out BEFORE you chase & spend $$ on parts.
Thats probably what you have ( without seeing schematic ).

73 Zeno:smoke:
LFOD !

Thanks!!! I had a Zenith from the late 50s that used that same value resistor on the line. I'll try it

Chris

...

Based on the description it sounds like a standard modern CL-90 thermistor would sub... If you're ordering caps for it just add one or two to your cart on mouser or digikey, install it, and have a set you don't need to power up with a variac at the end of the resto. (I'd wait till the recap is done to install the thermistor).