Led from center terminal of the A socket to A3 is not lighting up

[Andrew Catero]

When I was doing the voltage check - A2 was initially 127 volts and I noticed LED was not lit.  The rest of the voltages were correct.

I re-soldered A3 and center or Terminal Socket and A4 too.

Now when re-testing the Voltage at A2 is 61 volts and the LED is not lit .  The voltage at 18 also dropped to 61 volts too after re-soldering. Before I did this the voltage was in the correct range.

Not sure what to troubleshoot next?

 

[Paul Birkeland]

A2 is a grid on the 6DJ8.  It goes to ground and should be at 0V.  There's nothing that will make its voltage that high short of it touching A1 by accident, a miswire, or a part landing where it shouldn't.  The lack of illumination by the LED isn't important at this stage of diagnosis.

If you post photos of A side socket, we could probably see what went wrong.

 

[Andrew Catero]

Sorry about that. I meant to say  the voltage check on Terminal 2 is at 61 volts.  It was initially at 127 volts before I tried re-soldering A2 and the center of A socket.

I am attaching a picture.

 

[Andrew Catero]

Here is a better pictures

 

[Paul Birkeland]

You should go through and trim all those component leads that are sticking out in various places.  The lead coming off the back side of terminal 2 has very high voltage on it.  If it dips down a little and touches the chassis, bad things will happen.

Terminal 2 being 61V indicates that you have very strong emission from one half of your 6922, and you may find that this voltage increases a bit as you use the Reduction for several hundred hours.

I would add some solder to 4L, as it doesn't look super well connected.

If an LED on the 9 pin socket isn't lit, you can measure the DC voltage at the pin where it connects to help determine what might be going on.

-PB

 

[Andrew Catero]

I trimmed the components and re-soldered the Terminal 4 connection plus the other Terminal 1-8 connections. The LED still does not light up.

On socket Pin A3 - I get 1.33 volts
On Socket Pin B3 - I get 1.55 volts if that matters
I get 0 volts on the center of the socket

Terminal 2 is 55 volts
Terminal 7 is 66.9 volts
Terminal 13 is 61.6 volts
Terminal 14 is 62.1 volts
Terminal 15 is 66.7 volts

The rest of the Terminal numbers are in the required voltage range.

 

[Paul Birkeland]

What voltage do you see at A2?  I also see some stray leads around A4/A5.

 

[Andrew Catero]

I think I found the problem the resistor 1.0uf 50v Z5U is melted/broken from the RCA ground to  A4. 

I will get a replacement and retry.

Thank you for your help and patience.

 

[Doc B]

That's a capacitor. Do replace it. It's not clear if that will solve all the issues, but it's a step in the right direction.

 

[Andrew Catero]

After getting the replacement parts.

The LED from center terminal of the A socket to A3 is lighting up now.

During the voltage check,

Terminal 2 is 62.9
Terminal 7 is 67.3
Terminal 13 is 62.5
Terminal 14 is 62.5
Terminal 15 is 67

The rest of the voltages are fine.

is this close enough to try out or do I need to check something else?

Thanks

Andy

 

[Paul Birkeland]

Those voltages indicate stronger than normal emission, which is a good sign for the tube set that you received!