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  #16  
Old 10-30-2008, 07:31 PM
MRX37 MRX37 is offline
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I took the chassis out to start checking caps, and I'm glad I did. I haven't found any bad or even marginal caps yet, but some weird part on the board broke off.

This part kinda looks like a disc cap. It's situated in the power section, between the fuse and where the degaussing coil plugs in. I noticed that the leads on it looked like they were detaching. When I touched it, the metal disc detached from the leads. I tried to solder the leads back on, and the disc broke in half due to the heat.

It looks like a simple metal disc. My ohmmeter didn't read any significant resistance through it. Could I just solder the two leads together to bridge the connection, or is this some kind of important part?

PS: The metal disc has a number on it: 100- 0/A A170D
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  #17  
Old 10-30-2008, 08:20 PM
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zenith2134 zenith2134 is offline
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Umm....Degaussing thermistor? Just a guess. It may not show resistance since its open until the degauss circuit kicks in at which point it gains resistance and then dies down with temperature.

Or not. Pic?
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  #18  
Old 10-30-2008, 09:01 PM
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Last edited by andy; 12-07-2021 at 05:00 PM.
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  #19  
Old 10-30-2008, 09:15 PM
MRX37 MRX37 is offline
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Quote:
Originally Posted by zenith2134 View Post
Umm....Degaussing thermistor? Just a guess. It may not show resistance since its open until the degauss circuit kicks in at which point it gains resistance and then dies down with temperature.

Or not. Pic?
Here's a (crappy) pic of the disc. My camera does NOT take good pics of small objects.



And here's a shot of the board with an arrow showing where the disc came from.



EDIT: Er, Andy, I already cracked it... now what?
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  #20  
Old 10-30-2008, 09:25 PM
MRX37 MRX37 is offline
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If it's the degaussing thermistor, can I just use one from one of the TV chassis's I have lying around? I have several boards for 19" and larger TV's, or does the CTC 158B chassis need some kind of special thermistor?
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  #21  
Old 10-30-2008, 09:57 PM
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zenith2134 zenith2134 is offline
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Try and either look at the disc for a rating or search the part number online. Use one with a similar rating. Voltage should be the same since its usually AC line-driven, but make sure.

Sure, you can use a different one. Just make sure you use one with a similar physical size---chances are it'll work.

To be certain though, swap the thermistor AND the degauss coil.
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  #22  
Old 10-30-2008, 10:09 PM
MRX37 MRX37 is offline
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I'm thinking of a thermistor from a 2002 Phillips 19" set that's a similar size... actrally just a hair larger. I'll try that one.
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  #23  
Old 10-30-2008, 10:43 PM
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radiotvnut radiotvnut is offline
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This is a common problem and I just pull one from a junk chassis. This circuit is really not that critical; so, just about any thermistor taken from the degaussing circuit of a junk board should work.
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  #24  
Old 10-30-2008, 11:05 PM
MRX37 MRX37 is offline
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Quote:
Originally Posted by radiotvnut View Post
This is a common problem and I just pull one from a junk chassis. This circuit is really not that critical; so, just about any thermistor taken from the degaussing circuit of a junk board should work.
Woo hoo, and I have plenty of junk boards to try!
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  #25  
Old 10-30-2008, 11:17 PM
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zenith2134 zenith2134 is offline
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Its true. I suggested finding one of similar size so that it ill fit better and also put less stress on the existing coil. If you swap the coil too then don't worry.

Let us know how she turns out; the closest set I had to that one was a CTC-130C from 1987. It had stereo with bass/treble/balance, and OSD with 3 AV inputs. No SVideo, unfortunately. Gave that one away after it started scaring me (unusual occurences.)

Are you running the RCA with a cable/converter box or an antenna? I ask because since it has SVideo, you can figure out which unit has the better comb filter, and either pipe composite into the set or use SVideo.
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  #26  
Old 10-31-2008, 12:19 AM
MRX37 MRX37 is offline
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I'm running this set off basic cable, and using the S video to receive video from one of my computers. This particular colortrak model has a *very* good S video picture. Sharper then most TV's. You can actually make out small text... with the resolution at 1024x768!
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  #27  
Old 10-31-2008, 12:53 AM
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are ColorTraks the ones that have the incredibly smooth picture?
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  #28  
Old 10-31-2008, 11:42 AM
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I had one in a late 80s RCA that did the same thing so I installed one from my junk box-it tripped the breaker. I then tried one from a junker Zenith and it worked fine.

You don't happen to have a CTC159 chassis in your pile, do you? Have a friend who has been looking for some parts off one.
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  #29  
Old 10-31-2008, 12:52 PM
MRX37 MRX37 is offline
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No CTC 159 chassis.

Okay, I put in another thermistor, and turned the TV on. I heard the degaussing noise, then the internal fuse blew! Can the wrong type of thermistor cause the fuse to blow?
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  #30  
Old 10-31-2008, 01:38 PM
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Yeah, that was what happened to me. I said the breaker blew but after thinking about it, the fuse in the set blew. You'll have to try another thermistor.
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