Need some help!

Gobes · 1105

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Offline Gobes

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on: January 30, 2021, 11:14:19 AM
Folks, need some help. I just bought the S.E.X Kit a few weeks ago and built the amplifier.. It worked amazing!
I decided to upgrade it as i got the upgrade kit, I followed the exact instructions and it does not seem to work.
Just some questions:
1. Can someone please confirm that the resistors from 6U and 2U  as well as 16U to 20U need to be clipped off?
2. Is the 6FJ7 Tube a separate tube that i should get Vs what came with the package ( some GE Tubes that did not have any name)

Thanks for your help



Offline Thermioniclife

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Reply #1 on: January 30, 2021, 11:24:38 AM
Yes the resistors you mentioned are to be clipped off. and then you wire the c4s board to those terminals. The 6fj7 tubes are the one's
that came with the amp when you built it.

Lee R.


Offline Gobes

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Reply #2 on: January 30, 2021, 11:31:40 AM
That is exactly what i did and also checked the instructions and soldering multiple times..How do i know if the issue is with the circuit board? Its funny, i need to get a new voltage meter as it just went dead on me before i could measure anything and hence was not able to measure the voltages.. However, when powered the amp on on the tube lights came on.. 
Question:
Can the tube lights turn on even when there is an issue with the circuit board? given that i dint specifically measure the voltages due to the issue i ran into?



Offline Thermioniclife

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Reply #3 on: January 30, 2021, 11:49:31 AM
When you say the tube lights I assume you are talking about the heaters in the tubes, In that case yes they can. I think my next question is did you add wires to terminals 2u 6u 16u and 20u plus a ground and solder them to the c4s board? IF you did are the small led's on that board glowing? Perhaps some pictures can help.

Lee R.


Offline Paul Birkeland

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Reply #4 on: January 30, 2021, 11:52:10 AM
You will need to get your meter working and let us know what the "I" and "O" voltages are on the C4S board. 

If the amp worked prior to the C4S installation, you have 6FJ7s.

The tubes can absolutely glow even if the amp isn't working properly. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Gobes

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Reply #5 on: January 30, 2021, 02:02:01 PM
Thanks folks, I just rechecked only 1 led lights up. Please see the picture. Seems like the issue is there, what do you recommend I do to address this?
I also rechecked the wiring and it was accurate as per the manual



Offline Gobes

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Reply #6 on: January 31, 2021, 04:55:36 AM
Folks, any thoughts from the picture?



Offline Paul Birkeland

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Reply #7 on: January 31, 2021, 05:34:02 AM
Your picture is wildly out of focus.

You need to measure the DC voltages on the "I" and "O" terminals in order for us to help you determine what's going on.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Gobes

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Reply #8 on: February 07, 2021, 11:02:10 AM
I checked once more, and ensured that there was no contact between resistances the back of the board during solving. I noticed that the DC voltage was 10V where I was supposed to measure vs 50V-90V. I rechecked the circuit multiple times and seemed perfectly fine!. I think it's an issue with one of the components ( resistance, transistors etc). I rolled back without the upgrade.  Still amazing!.
Who do I contact with component issues?
I'm looking to move on to my next project, looking for an integrated amp (Kaiju or stereomore with jager). Any thoughts?



Offline Paul Birkeland

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Reply #9 on: February 08, 2021, 05:34:10 AM
I think it's an issue with one of the components ( resistance, transistors etc).
It's not.

Who do I contact with component issues?
What component is bad?  How do you know a component is bad?  Which component do you want to replace?

If you want to get this working, you need to put the board back in and provide me the IA, IB, OA, and OB voltages.  Noticed in my last post that I asked for these four voltages and you only measured one of them.

It would also be really helpful to see in focus photos of the front and back of the PC board.  Most frequently with an issue like yours we find a soldering issue on the board or a component that isn't properly installed.   The last time I saw a component randomly bad straight out of the box was in 1999 and the company who made/sold has long since gone out of business.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Gobes

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Reply #10 on: February 08, 2021, 06:06:26 AM
Thank you for your input. Seems like i was following the manual which asked me to measure OA and OB ONLY (unless i missed something), which i measured and posted. Do you think its a bad idea for the manual to be updated given its the master source? This may help in the future. This could be a soldering issue at my end (which i rechecked a number of times to make sure there was no contact between the components when soldered), if you think that all the components are perfect!
« Last Edit: February 08, 2021, 06:14:27 AM by Gobes »



Offline Paul Birkeland

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Reply #11 on: February 08, 2021, 06:19:22 AM
Thank you for your input. Seems like i was following the manual which asked me to measure OA and OB ONLY (unless i missed something), which i measured and posted.
You need to measure the DC voltages on the "I" and "O" terminals in order for us to help you determine what's going on.


Do you think its a bad idea for the manual to be updated given its the master source? This may help in the future.
The voltage check in the manual is intended to be as simple as possible.  Either you get the correct voltages at the "O" terminals or you don't.  Determining why you aren't getting the proper voltages at the outputs will require more measurements than someone would need to do whose board is otherwise working properly. There are not a ton of voltage checks in the upgrade manual because it is assumed that you have started with a working stock kit and you just need to check the operation of the C4S board itself.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man