Scored an Admiral 19A11

[Crist Rigott]

Originally Posted by jr_tech

If it has only increased to 21K, I doubt that the voltage would drop that much (75 to 8.2 volts)... is the 6J6 ok?

jr

Yeah, I agree. I'll swap out the 6J6 next time.

[Crist Rigott]

I pulled A4 1st IF transformer off the tuner to replaced the 15K resistor. It consists of the 15K resistor, a coil, and 2 mica caps at 10pf and 130pf.

Here is what it looks like:



I was expecting some "real" mica caps. Now I'm concerned that those caps could develop silver mica disease. I'm having some real trouble getting a cap reading on each of those with my cap checker. I could cut them in half and install real mica caps.

What do you think?

[jr_tech]

Is the 10 pf leaky to ground? that could pull down the plate supply to the 6J6. Otherwise, I think that I would leave them alone, and try to figure out the reason the 6J6 plate voltage is so low first.

jr

[old_coot88]

With the 6J6 removed, check the voltage at pin 2 (plate), and see if it still lugs down.

Dittos to jr_tech on leaving the caps alone unless one is leaky/shorted. Their values are for bandpass-shaping so are fairly critical.

[Crist Rigott]

Originally Posted by old_coot88

With the 6J6 removed, check the voltage at pin 2 (plate), and see if it still lugs down.

Dittos to jr_tech on leaving the caps alone unless one is leaky/shorted. Their values are for bandpass-shaping so are fairly critical.

I checked the voltages on V1 and V2 with the tubes removed.

[Crist Rigott]

Well Late this afternoon I decided to replace the mica caps in A4. I thought that while I had it out, why take the chance. I replaced them with 500V 5% micas. I had the 10pf but didn't have the 130pf so I put 2 in parallel. When I checked them with my cap checker I got 129pf. Good enough. And I also changed out the 15K resistor which read 23K once removed. BTW, all the caps in the tuner were replaced using carbon film caps.



I re-installed the tuner and I now have a much better picture.



On to the alignment.

[jr_tech]

Excellent! did the plate voltage on the 2 6J6 plates change?

jr