Nady 1050 voltages-Finished

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I'm having problems getting proper voltages on my tube pins on a Nady 1050. I've read amzavareei's thread regarding the problems he was having, but can't exactly determine my problem yet.

Here's what I've done
1. Removed the CF
2. Removed C9 and C10
3. Replaced C1, C2, and C8
4. Replaced the capsule
5. Replaced the transformer

The voltages I'm getting at the tube pins are the following (no tube):
1-72.9
2-0
3-0
4-6.7
5-6.7
6,7,8-0

One of the voltages Marik recommended checking was R5. On one side I get 46.3V and the other I get 0.9V. Way off from what he said I should find there. I also checked pin 3 on the connector and I'm getting about 19V there
I'm know I probably just need to stare at the darn thing till I see the problem, but any tips as to where the problem could lie would be great.

http://www.apexelectronics.com/pdfs/smapex460.pdf

Thanks,
Craig

Hope no one is offended that I also posted this at HomerecordingBBS as well. I'm getting sick of messing with this thing!

[quote author="craigmorris74"]--------------------------------------------------------------------------------

The voltages I'm getting at the tube pins are the following (no tube):
1-72.9
2-0
3-0
4-6.7
5-6.7
6,7,8-0

One of the voltages Marik recommended checking was R5. On one side I get 46.3V and the other I get 0.9V. Way off from what he said I should find there. I also checked pin 3 on the connector and I'm getting about 19V there
[/quote]

What are you measuring with? Your basic multitesters are still sometimes no match for a 1+Gig impedance.

Test it with the tube in - hopefully you'd be getting a volt or so at the cathodes. Don't zap yourself.

I'd love to see a pic of your work.

I removed the cathode follower.

What pins do you mean by at the cathodes? Sorry, but I'm learning as I go.

I made this schematic to reflect the edits I've made:
http://www.angelfire.com/ky3/craigorris74/a460schemCFremoved.JPG

Also the power supply voltages are 106V at B+ and around 20 V at the "variable voltage" pin. This voltage starts out higher but drops after a few seconds.

did you check the 115 230 switch?

Gus, didn't check that switch. Shouldn't it be set on 115 for the US? I can't check it now, but will when I get home.

[quote author="craigmorris74"]I removed the cathode follower.

What pins do you mean by at the cathodes? Sorry, but I'm learning as I go.
[/quote]

Pin 3 should have around a volt on it with the tube plugged in. The K resistor keeps the cathode floating a volt or so above ground (usually) thus negatively biasing the grid in respect to the rest of the tube.

R2 should have a decent voltage drop across it, so should a measurement between pins 1 & 3. I'm guessing B+ at pin 1 is about 1/2 to 2/3 B+ at the cable side of R1.

Are your capacitors in backwards? I guess I'm just used to drawing my electrolytics as flat on the positive side.

I've flipped the electrolytics so they're not backward.

I finally got a glowing tube yesterday, and my voltages seem to be reasonable. However, I knocked a wire or two off the tube socket when putting the body back together. Now I've got no glowing tube again. I'm using a different power supply in case your wondering why the plate supply is higher (at least that's what I think the deal is).
My voltages at the tube are:
pin 1-155V
pin 2-0V
pin 3-0V
pin 4-6.7V
pin 5-6.7V
pin 6,7,8-0V

I'm getting confused and need to take a break.

Thanks for your help,

Craig

Pin 3 *Should* have at least .5 V across it. Check pin three's resistance to ground.

If there is no reference to ground on pin 3, or the number is high like in the 100s of kOhms then either:

R7 is shorted or bunk and the resistor/solder joints need to be checked.

OR

Check your ground trace to make sure it's connected to the ground at the cable.

Have ya tried a new tube?

IMHO

OK. Going to recheck pin 3 and the ground trace.

WTF! I'm getting 6.7V at pin 3!

Got the mic working. Every time I would solder one wire on the tube socket, I'd pull a wire off. I finally carefully retraced all the wires and compared them to the schematic and found the problem. What a novel idea! Thanks for everyone's suggestions. I could post samples if anyone is interested. The mic now has the Peluso CEK-12, Ansar coupling cap, Black Gate filtering caps, cathode follower removed, and Cinemag CM 2480 transformer.

Here's the final schematic (the original was drawn by someone on this forum, with edits by me):
http://www.angelfire.com/ky3/craigorris74/a460schemCFremoved.JPG

Craig