no sound right channel/terminal 1 voltage 150

Jokman · 3217

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Offline Jokman

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on: July 03, 2023, 04:33:54 PM
just finished crack build. everything checked out but terminal 1 voltage is high and no sound right channel. I checked thru forum as far as I can tell rca's aren't shorted and all visual inspections of solders look good.

any ideas what could be amiss with that combination of problems?

thank you



Offline Paul Birkeland

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Reply #1 on: July 03, 2023, 05:11:15 PM
Can you post some build photos?  Are both halves of the 12AU7 glowing?

Definitely do not try to listen to an amp that doesn't pass its voltage checks under any circumstances.  It's possible to damage your headphones depending on the specific problems you have, so those issues need to be resolved first.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Jokman

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Reply #2 on: July 04, 2023, 06:59:09 AM
thank you Paul
both halves of tube glowing. I took picture. not sure what are best photos to show you so I tried to take a few in focus
hope my solder doesn't make u cringe.
thanks again.



Offline Jokman

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Reply #3 on: July 04, 2023, 07:03:23 AM
3 more photos sorry had technical difficulties



Offline Jokman

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Reply #4 on: July 04, 2023, 07:05:15 AM
3 more photos sorry had technical difficulties



Offline Jokman

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Reply #5 on: July 04, 2023, 07:05:41 AM
3 more photos sorry had technical difficulties



Offline Paul Birkeland

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Reply #6 on: July 04, 2023, 07:33:18 AM
B5 is not soldered.

The 3K resistor leads that poke out of 7L and 9L aren't trimmed.  If those touch the chassis, you will burn up the power supply, power transformer, or blow the fuse.

I don't see the LED that goes to A8.

The green wire going to A4/A5 has too much jacket stripped off.  If that bare bit of wire touches the chassis, that will destroy the power transformer.  I would heat up those joints and slip more of the wire through so this doesn't happen.

The white wire going to A7 has no mechanical connection.

Can I see the wiring at your headphone jack?

(Your braiding looks very nice BTW)

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Jokman

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Reply #7 on: July 04, 2023, 09:32:53 AM
THANK YOU
turns out I had left off the led as you saw and one of the resistors on the headphone jack. seems like if I see two similar directions in a row I disregard one of them. that's a bad bug ill have to go in for re programming.

pic of headphone jack attached. I made the other changes that you so easily picked up

thank you I'm going to test resistance and voltages again now.




Offline Jokman

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Reply #8 on: July 04, 2023, 09:41:33 AM
im now bathing in the warm glow of glorious tube amplification.

without question the finest customer service in the solar system.

THANK U.



Offline Paul Birkeland

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Reply #9 on: July 04, 2023, 12:22:50 PM
It is extremely common to find a loose black wire at the headphone jack, so I would also double check that when you get a chance.  Are there any other leftover parts in the kit other than the #8 self tapping screw?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Jokman

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Reply #10 on: July 04, 2023, 12:30:43 PM
no other loose parts. after having that initial part as 'extra' early on in assembly I mistakenly assumed that the extra led and resistor were exactly that.

what was the bit you said before about white wire to a7? I couldn't find that in directions or in picture of final assembly.

thank you again. my next build I'll be more careful.



Offline Paul Birkeland

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Reply #11 on: July 04, 2023, 12:32:20 PM
When you attach a wire or lead to a terminal or tube socket before soldering, it needs to at least be bent up so it won't move.  If you just pass a wire through a hole and solder it, there's a very good chance that the wire can slip out later.  It's also a very common condition that can create random noises down the road.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man