View Full Version : Thermistor help


Dave A
07-04-2007, 10:54 AM
My CTC9 blew a thermistor in the AC line direct to the transformer. 79 ohms cold, .49 ohms hot, 70 ohms nominal. What can I use for a sub until I find a replacement?

Dave A

Big Dave
07-04-2007, 01:09 PM
I would bypass it. Perhaps Moyer might have a replacement. I looked at the print, and I don't thing bypassing it will hurt anything.

frenchy
07-04-2007, 06:22 PM
I would bypass it. Perhaps Moyer might have a replacement. I looked at the print, and I don't thing bypassing it will hurt anything.


I bypassed on one of my RCAs, I think it's just to help limit a current surge when the set is first turned on but not a big deal to leave it out.

Dave A
07-04-2007, 09:33 PM
I was thinking a fuse, but there are enough already. Bypass it is. And while it is out, the focus resistor string gets changed and maybe I can get the focus off the end of the range. Thanks guys!

Dave A

Bill R
07-04-2007, 09:54 PM
Just bypass it. It is for the degausing circuit. When it is cold the high resistance causes current to flow through the degausing coils. As it warms up the resistance drops, effectively shorting the coils out of the circuit, and allows current to flow to the rest of the set.

Bill R

avalon1308
07-05-2007, 01:57 AM
It is bypassed on most of mines but "moyers electronics" does have them. Just received a few of them from the store. Maybe not a real need for the set but I like to see the set come on slowly.

holmesuser01
07-05-2007, 10:25 AM
This thermister is what caused the 'dead set' syndrome that got me the CTC-10C that I own today, not mentioning the broken kine...

I bypassed the thing in 1975, and have never had any problems whatsoever.

Bruce

frenchy
07-05-2007, 03:30 PM
Just bypass it. It is for the degausing circuit. When it is cold the high resistance causes current to flow through the degausing coils. As it warms up the resistance drops, effectively shorting the coils out of the circuit, and allows current to flow to the rest of the set.

Bill R

Is that what it's for? I don't remember exactly which set I did it on but I could swear that the set I bypassed it on didn't even have a degaussing coil (?) I think somebody told me it was to prevent too large of an initial surge into the cold set to protect the power supply tubes... or something like that.

Did any CTC-9s have a degaussing coil?

Big Dave
07-05-2007, 05:11 PM
Late production might. Mine doesn't.

Dave A
07-05-2007, 06:56 PM
Mine is a CTC9F with no degaussing. Just the thermistor on the AC in right after the switch.

Not no more. I cut it out and twisted the leads and soldered them. Back to life with no noticeable change. I didn't have 2W 22meg resistors for the focus string so that is another day.

I did order a few from Moyer for the next time I am in the set. I have a CTC10 that will need some sooner or later.

Thanks for the interest and help.

Dave A

Bill R
07-06-2007, 12:49 PM
yes with no degausing coils it would simply be an inrush current limiter.

Bill R