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Old 05-10-2017, 05:51 PM
Jon A.'s Avatar
Jon A. Jon A. is offline
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Join Date: Jun 2013
Location: Canada
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Choosing a thermistor

I need to replace a 60-ohm PTC thermistor. I can't find a 60 so I'm wondering if a 50 can be used instead. If my guess is correct, the degaussing coil will just stay on a trifle longer with no ill effect.
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Old 05-10-2017, 08:48 PM
Findm-Keepm's Avatar
Findm-Keepm Findm-Keepm is offline
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Considering most PTC/Posistor degaussing thermistors have a 20% tolerance to start with, no problemo.

Just don't use a posistor from a 36" set in a 13" set. Big difference in thermal/resistive "hysteresis" that'll cook a d-coil on a smaller set. I saw this once with a Samsung 13" set serviced by someone else. No degaussing, so I replaced the positor, only to find an open d-coil - melted aluminum winding...

Tip to those saving posistors (little boxy thermistors for modern set degaussing) from junked sets - mark the screen dimensions on the posistor, as there is no cross reference for the markings on the units - some Murata ones have a partial part number, but most are house marked, so you have no idea if a 617-40 or an A28-2 will replace a DAF40.....
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Old 05-14-2017, 06:22 AM
Jon A.'s Avatar
Jon A. Jon A. is offline
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I didn't know degaussing coils could open, I assumed they would just get so hot they would trip a breaker or start a fire. I used a coil from a 19" set in a pinch when I had to do some manual degaussing. I ran it at probably less than half of line voltage but still it got too hot to handle in about 10 seconds. Buried the needle on the Powerite too.

I looked over the chassis of a junk 25V Hitachi for a posistor but couldn't spot one. Of course it seems Hitachi used some weird engineering, much more complex than I care to dig into. I got its oversized coil anyway so now I can mock up a decent manual degaussing coil. I hear a 100-watt light bulb makes a good current limiter for those.
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