Admiral Telebar help

[M3-SRT8]

Originally Posted by Radiotronman

I tested all resistors around the horizontal oscillator and didn't find any resistors way out of tolerance. There are three mica caps on this 6SN7 tube, could one of these being leaky kill the circuit? What else could cause this noise and kill hv?

Ooooh, yeah. Micas in the Horizontal circuits are prime suspects now. They take a beating there.

[Radiotronman]

I replaced a few micas around the horizontal output tube and a couple resistors, but no improvement. Pin two on the horz output tube is supposed to be 305v, and I measure 250v. The mica cap on the horizontal lock coil is a 3900pf mica, which I don't have. Any more ideas?

[M3-SRT8]

It could be an IF stage. When the noise starts try tapping each if tube.

I had a 721 TCS that had these symptoms and it wasn't a horizontal sweep or synch problem. Swapped out a video if tube and it was fine.

I'm reaching here, but, there it is.

[Electronic M]

Originally Posted by Radiotronman

The mica cap on the horizontal lock coil is a 3900pf mica, which I don't have. Any more ideas?

3900pF = .0039uF...Get a film cap...If you don't have one that is close tack 4 .001 caps in parallel for temp.

[Radiotronman]

Ok, thanks Tom. I'll try that!

[Radiotronman]

I found that if I worked the horizontal lock coil in and out, at certain points the noise would stop. I still have little to no hv though. Thanks for the help guys!

[old_coot88]

Couple of questions. If you disconnect the plate connector from the HV rectifier, can you draw an 'air arc' from the connector (using a well-insulated screwdriver)? It should draw a nice quarter-inch to half-inch blue arc off the screwdriver. With the connector re-connected, can you draw the same arc?
Is the tube running hot?

[Radiotronman]

I cannot draw an arc from the hv rectifier with it connected or not.

[Radiotronman]

I replaced the 3900pf with a .0039uf film cap, but still no hv. I'm starting to run out of ideas on what is going on?

[timmy]

Sounds like a short somewhere, is there a doorknob cap in that set ?

[Radiotronman]

There is a doorknob cap in this set. How do you test them, a continuity check?

[old_coot88]

Since you weren't getting any arc off the HV rectifier plate connector (even with the connector lifted and floating), what does that tell you?

[timmy]

Ok I missed that...

[Radiotronman]

I'm not sure old coot-what does it tell me?

[Electronic M]

If you can't draw an arc from the fly lead that normally connects to the HV rect. top connection, when that lead is disconnected from the HV rect then it means the fly is not generating any HV.

Timmy was suggesting that you test to see if the doorknob was loading down the HV...Which is irrelevant at this point because if there is no HV to load down.