CTC 10 HV affected by brightness

[Turle]

Originally Posted by miniman82

You need to run the horizontal oscillator setup procedure outlined in Sams for that chassis. The horizontal circuit is the most finicky of all the circuits in a TV minus perhaps the tuner and IF strip, so if one adjustment is out of whack it will do funny things. Problem is- they're all related so it's difficult to pin down what exactly is causing the problem. When I troubleshoot horizontal circuit issues I do the following:

Begin with HV, is it high enough?

If not, you must figure out why. Possible symptoms include HV pot needs adjusted, shunt tube is dragging down HV which is usually a drifted resistor in it's grid circuit if the pot doesn't get HV high enough, horizontal drive control not set properly (if so equipped, some chassis have one some do not), weak horizontal output tube, weak horizontal oscillator tube.


If you initially have enough HV but you can't get reasonable brightness try rolling rectifier tubes, there can sometimes be a huge difference in how HV responds to various tubes because of their construction, emission and internal resistance. I've taken to installing solid state stick rectifiers in most of my sets, they make HV a bit stiffer.

Lastly if you don't get some improvement, try the horizontal efficiency coil. If it's not set correctly, the circuit can struggle to push enough current through the flyback leading to sluggish performance. Sams will have the steps to follow to set it correctly, just download it and go through it.

Okay after messing around with it all night, I’ve came to a possible new clue. When the HV decreases, the horizontal output current increases. Is this an indication of a shorted flyback turn? It doesn’t seem to get very hot

[miniman82]

Originally Posted by Turle

Okay after messing around with it all night, I’ve came to a possible new clue. When the HV decreases, the horizontal output current increases. Is this an indication of a shorted flyback turn? It doesn’t seem to get very hot

If you had a shorted turn it wouldn’t work at all.

Current goes up because you have a heavy load on it, which is normal. What does “messing around all night” mean? Did you run the setup procedure? Did you verify 1ua cathode current on the shunt tube with a dark screen? Did you null the efficiency coil? Did you verify the double humped waveform with a scope?

You haven’t given us much to help solve your issue...

[Turle]

Originally Posted by miniman82

If you had a shorted turn it wouldn’t work at all.

Current goes up because you have a heavy load on it, which is normal. What does “messing around all night” mean? Did you run the setup procedure? Did you verify 1ua cathode current on the shunt tube with a dark screen? Did you null the efficiency coil? Did you verify the double humped waveform with a scope?

You haven’t given us much to help solve your issue...

I don’t wanna sound like an asshole but I don’t really know what half the stuff is you’re talking about. I don’t have a ton of color set experience

[Electronic M]

Originally Posted by Turle

I don’t wanna sound like an asshole but I don’t really know what half the stuff is you’re talking about. I don’t have a ton of color set experience

Do you have the Sam's or RCA service data for your set? (The Sam's is available for free on the ETFs website if you navigate to early color TV then technical information) The procedures Nick/miniman mentions are standard service adjustment procedures detailed in both of those manuals and are the first things you should do when you experience incorrect horizontal performance.

Nulling the efficiency coil especially should be done to all RCAs that have been brought out of decade long dormancies ...and might be all it needs if you haven't done that yet.