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May 20, 2019, 11:37:17 am

Author Topic: Led from center terminal of the A socket to A3 is not lighting up  (Read 628 times)

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Offline Andrew Catero

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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?


Offline Paul Birkeland

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #1 on: October 12, 2017, 02:17:00 pm »
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.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Andrew Catero

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #2 on: October 12, 2017, 05:49:49 pm »
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.






Offline Andrew Catero

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #3 on: October 12, 2017, 05:51:51 pm »
Here is a better pictures

Offline Paul Birkeland

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #4 on: October 13, 2017, 04:27:59 am »
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
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Andrew Catero

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #5 on: October 13, 2017, 06:26:48 am »
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.


Offline Paul Birkeland

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #6 on: October 13, 2017, 04:40:19 pm »
What voltage do you see at A2?  I also see some stray leads around A4/A5.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Andrew Catero

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #7 on: October 14, 2017, 06:25:18 am »
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.

Offline Doc B.

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #8 on: October 14, 2017, 07:29:12 am »
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.
« Last Edit: October 14, 2017, 07:31:17 am by Doc B. »
Dan "Doc B." Schmalle
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Offline Andrew Catero

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #9 on: November 05, 2017, 10:08:58 am »
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

Offline Paul Birkeland

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Re: Led from center terminal of the A socket to A3 is not lighting up
« Reply #10 on: November 05, 2017, 03:34:45 pm »
Those voltages indicate stronger than normal emission, which is a good sign for the tube set that you received!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man