Soft turn on for old color unit for color??

[frenchy]

Some sets had a thermistor built into the tv-end of the power transformer circuit, to reduce the initial surge into the set... so maybe if a set's circuit didn't have one it could be added? My ctc-10 had one but it was bad and I just removed it from the circuit.

[RetroHacker]

Once the filter caps and rectifiers are replaced, I can't see any reason to worry about damage. I mean, if you're replaced critical power supply components, then the power supply should be good as new, and these sets were designed to operate this way. If you haven't replaced the filters, then it's really just a matter of time before you need to replace them, and I don't know if trying to soft start the set every time will really help prolong their lives. Also, you don't want to damage the HO tube - these are much harder to find than the electrolytic capacitors are!

-Ian

[Pete Deksnis]

As I saw it, the Thyrite in the CTC10 was there to limit the filter cap initial charging current, protect the power supply diodes that have to pass the high current surge of the filter caps, and even as a secondary benefit, the on-off switch sees much less turn-on stress. It also gave me a warm fuzzy when I watched the #47 lamp ramp up to full brightness in the two seconds or so that it took, because all the filaments were slow-starting too. To me Thyrite is a Stress Tab for electronics.

[frenchy]

Originally Posted by Pete Deksnis

As I saw it, the Thyrite in the CTC10 was there to limit the filter cap initial charging current, protect the power supply diodes that have to pass the high current surge of the filter caps, and even as a secondary benefit, the on-off switch sees much less turn-on stress. It also gave me a warm fuzzy when I watched the #47 lamp ramp up to full brightness in the two seconds or so that it took, because all the filaments were slow-starting too. To me Thyrite is a Stress Tab for electronics.

Anybody know of an available online source for a suitable replacement for this part? It is a thermistor, 79 ohms (cold). thanks
Speaking of switches, the switch in my hair dryer went bad this morning, I could see flames shooting out of it thru the white plastic housing. It finally quit and I finished drying my hair (which now smells like a burned transformer!) and then I unplugged it, ran water thru it and tossed it, time to buy another one!

[vintagecollect]

Thanks for fantastic information on this.


Does anyone have several thyrites or varistors I can buy from?? Please PM. I was hoping a few seconds would be good enough. Wouldn't this help promote a longer life for ALL tubes, including CRT?? I was looking into this also to limit as much surge current going to CRT as possible to try and extend service life. Does varistor go in power transformer primary circuit, or somewhere a take off in secondary, for a gradual power on for B+ voltages??

[frenchy]

[QUOTE=vintagecollectDoes anyone have several thyrites or varistors I can buy from?? Please PM. I was hoping a few seconds would be good enough. Wouldn't this help promote a longer life for ALL tubes, including CRT?? I was looking into this also to limit as much surge current going to CRT as possible to try and extend service life. Does varistor go in power transformer primary circuit, or somewhere a take off in secondary, for a gradual power on for B+ voltages??[/QUOTE]

On the ctc-10 it is just wired in series with the main voltage coming out of the transformer and into all the filtering caps etc. Don't know if it would give longevity to any tubes, unless for some reason filaments are known to last a bit longer if they are brought up to full power slightly more slowly than instantly (?) Don't remember if the voltage for the filaments is even going thru the varistor to begin with, it may not be.

[andy]

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[Pete Deksnis]

Originally Posted by frenchy

On the ctc-10 it is just wired in series with the main voltage coming out of the transformer and into all the filtering caps etc.

Frenchy. Are you sure the device is wired into the secondary somewhere? Looked up the original schematic that came with the CTC10 and couldn't find it. Found the CTC10 RCA service literature and ditto, but I could have missed it.

Had to replace the Thyrite in that set in the latter sixties and I'm pretty sure it went in the primary of the power transformer. The fils are definitely in the loop because as I mentioned somewhere earlier, it takes the pilot lamp two seconds to ramp up to full brightness.

Pete