HERESY ... My CT-100 Color TV TUNER

[dtvmcdonald]

On a different topic ... I've been running my RCA-Sony setup with the full HV
system running in the CT-100, just disconnected from the CRT, with the AC input
at 108 volts to reduce heat. This works just fine (the thing runs well down even to
100 volts).

But I was thinking ... would it be better to simply unplug the HV and focus
rectifier tubes? Would this reduce stress on the horizontal output tube and transformer? Or would lowering the load cause the voltage to rise up, causing
even miore stress?

I could try it, but what about your opinion? Note that this is not the same
as doing that on a B&W set because color sets have essentially constant
HV current from the HV rectifier due to shunt regulation.

[Electronic M]

Originally Posted by dtvmcdonald

On a different topic ... I've been running my RCA-Sony setup with the full HV
system running in the CT-100, just disconnected from the CRT, with the AC input
at 108 volts to reduce heat. This works just fine (the thing runs well down even to
100 volts).

But I was thinking ... would it be better to simply unplug the HV and focus
rectifier tubes? Would this reduce stress on the horizontal output tube and transformer? Or would lowering the load cause the voltage to rise up, causing
even miore stress?

I could try it, but what about your opinion? Note that this is not the same
as doing that on a B&W set because color sets have essentially constant
HV current from the HV rectifier due to shunt regulation.

If I was in your shoes I would leave the HV loaded if you plan to run the horizontal. If you pull just the regulator and CRT and measure the HV it is probably substantially higher than rating. Having higher HV on the flyback puts it at increased risk of insulation breakdown.

[dtvmcdonald]

Originally Posted by Electronic M

If I was in your shoes I would leave the HV loaded if you plan to run the horizontal. If you pull just the regulator and CRT and measure the HV it is probably substantially higher than rating. Having higher HV on the flyback puts it at increased risk of insulation breakdown.

That is my thinking, but I decided to ask. However, what I suggest pulling is the
main HV rectifier. My feeling is that this will result in much higher peak
HV (AVC) voltage on the transformer. Of course, so will a dead HV rectifier
filament.

[Electronic M]

Originally Posted by dtvmcdonald

That is my thinking, but I decided to ask. However, what I suggest pulling is the
main HV rectifier. My feeling is that this will result in much higher peak
HV (AVC) voltage on the transformer. Of course, so will a dead HV rectifier
filament.

Yup the AC will be even worse with the rectifier heaters out of circuit. The regulator pulled was for illustration purposes. I'm sure RCA expected owners to fix their sets and not run them long with no picture.

One compromise you could try is to replace the HV rect tubes with solid state replacements. On my 21CT55 that is now a weekly use set being unable to source solid state 3A2 equivalents I put 4 5KV PIV rated diodes in series for the focus and 5 in series for the second one....The third stage I left tube so if the HV output were to short the tube would hopefully cushion the rest of the system.