Terminal 1 measures high in voltage test [resolved]

[Universe Man]

I measured terminal 1 as instructed and got a value of ~125v. Any suggestions? Passes resistance test and both LEDs and tubes turn on.

I’ll add that terminal 2 measures in the acceptable range.

 

[Paul Birkeland]

Can you post some build photos?  What are the voltages on terminals 1-10?  You can't have both terminal 7 and 9 have acceptable voltages with 125V on terminal 1.

 

[Universe Man]

1 120
2 160
3 0
4 161
5 118
6 0
7 128
8 0
9 126
10 0

 

[Universe Man]

Can you post some build photos?  What are the voltages on terminals 1-10?  You can't have both terminal 7 and 9 have acceptable voltages with 125V on terminal 1.

I checked over all the joints a couple times and they all seemed okay. Unless there is something I’m just missing repeatedly, which there might likely be, I’m not sure what could be wrong.

 

[Doc B]

Posting photos may help.

 

[Universe Man]

Posting photos may help.

I put a couple in a reply above

 

[Universe Man]

Posting photos may help.

Do you think more angles are needed?

 

[Paul Birkeland]

If you pull the 6080 and run the amp with just the 12AU7, what voltage do you get at terminal 1?

Also, can you carefully measure the DC voltage at A3?

 

[Universe Man]

If you pull the 6080 and run the amp with just the 12AU7, what voltage do you get at terminal 1?

Also, can you carefully measure the DC voltage at A3?

1 is 152 without the tube

A3 is 2v

 

[Paul Birkeland]

Looking back over this with fresh eyes, your voltages on 1 and 5 are too high.  This would have me more suspicious that you have a bad solder joint on the green twisted pair of wires running between the octal socket and the 9 pin socket, and you aren't getting the 12AU7 all the way hot because of that. 

 

[Universe Man]

Looking back over this with fresh eyes, your voltages on 1 and 5 are too high.  This would have me more suspicious that you have a bad solder joint on the green twisted pair of wires running between the octal socket and the 9 pin socket, and you aren't getting the 12AU7 all the way hot because of that.

I touched up those joints but t1 still goes up then settles around 122

 

[Paul Birkeland]

Is the 12AU7 glowing up top?

 

[Universe Man]

Is the 12AU7 glowing up top?

Yes

 

[Paul Birkeland]

Can you double check that you didn't get a 12AT7 by mistake?

Something just isn't adding up here...

 

[Universe Man]

Can you double check that you didn't get a 12AT7 by mistake?

Something just isn't adding up here...

Box says 12au7, tube text is worn down a bit and harder to interpret. Might look like it says At or something? What do you think?

 

[Paul Birkeland]

Can you see any printing on the tube?  I think you may have accidentally gotten a 12AT7.

 

[Universe Man]

Can you see any printing on the tube?  I think you may have accidentally gotten a 12AT7.

I can make out a 6679, online it says that’s a 12at7. Problem solved(ish)! I guess the question now is what to do about it…

Regardless of if I’m getting a replacement 12au7, is it safe now to finally use with my hd6xx? I see that it’s higher output, but the headphones are fairly high impedance.

 

[Universe Man]

Can you see any printing on the tube?  I think you may have accidentally gotten a 12AT7.

Also, do the voltage readings seem good considering it’s a 12at7?

 

[Paul Birkeland]

You definitely can't use a 12AT7 in the amp.  You can contact replacementparts(at)bottlehead(dot)com to let them know you got a 12AT7 by mistake.  Including a link to this thread is a nice idea, along with your name and mailing address. 

The voltages at terminals 1 and 5 would be about what I would expect for a 12AT7. 

 

[Universe Man]

You definitely can't use a 12AT7 in the amp.  You can contact replacementparts(at)bottlehead(dot)com to let them know you got a 12AT7 by mistake.  Including a link to this thread is a nice idea, along with your name and mailing address. 

The voltages at terminals 1 and 5 would be about what I would expect for a 12AT7.

Ok, I will take care of that.
Thank you for helping.