View Full Version : Three legged thermistor on a CTC-53?


Kamakiri
05-18-2016, 06:05 AM
Picked up a CTC-53 portable recently, and while giving it the once over, I spotted a weird thermistor with three leads towards the back of the chassis near the picture tube. Almost looks like a big integrator. The leads were separated. Never seen one before. Talked to a friend and said that those were a common failure point but he couldn't remember what they do.

In lieu of a Sams on this set, does anyone happen to remember what they do, and what would serve as a replacement?

miniman82
05-18-2016, 09:20 AM
Sure it's a thermistor and not a three legged MOV?

dieseljeep
05-18-2016, 10:11 AM
Sure it's a thermistor and not a three legged MOV?

IIRC, it's in the deguass circuit.
Strange thing, my basic CTC51K, 14" similar chassis, doesn't have a deguasser, never came with one. :boring:

Kamakiri
05-18-2016, 10:49 AM
Sure it's a thermistor and not a three legged MOV?

Might be, I've never seen one before so I'm not certain.

That's what Ed was thinking, something in the degauss circuit. I had thought of just unplugging the degauss and try firing it up. Might not be a bad idea to get a Sams on it first though to be on the safe side.

BigDavesTV
05-18-2016, 12:35 PM
Hey Tim, That is a three-legged thermistor, and is part of the Deguass Circuit. It's like two, 120 ohm thermistors back-to-back, for a total across of about 240 ohms. I have an extra N.O.S. in the package spare, if you want it.

rca2000
05-18-2016, 12:46 PM
I seem to recall those 3 leg thermistors being used on much newer SS sets. I THINK...one is right across the power line--designed to quickly heat the other one--which is in series with the degauss coil as usual. If they short--it WILL put a short on the AC line--at least it did on some SS sets.

I usually just omitted the second thermistor--if I could not get an original, put a standard PTC in the ckt in series with the coil--and the degauss ckt worked fine after.

Kamakiri
05-18-2016, 01:38 PM
Hey Tim, That is a three-legged thermistor, and is part of the Deguass Circuit. It's like two, 120 ohm thermistors back-to-back, for a total across of about 240 ohms. I have an extra N.O.S. in the package spare, if you want it.

That'd be awesome, really appreciate it Dave! :)

As a sidebar, can I just unplug the coil to test the set, or should I wait and install the replacement first?

zeno
05-19-2016, 10:59 AM
For a CTC53H or K OEM is #127227
Its 2X 250 ohm cold. You can resolder them in a pinch
if the discs are in good shape.

73 Zeno:smoke: