Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: 2Bornot2B on July 27, 2021, 10:19:20 AM

Title: 6dn7 with broken key on bottom; impedance switch positions
Post by: 2Bornot2B on July 27, 2021, 10:19:20 AM

Please excuse me if this has been discussed before, I tried searching for an answer and did not get a reference. I purchased a used SEX 2.1 (I think, it has CC4 and impedance switch) and the tubes supplied had the key on the bottom of the base broken off. The seller suggested just trying various positions, I do not believe that is something I am comfortable with without some input from the forum.
Secondly, would someone share the positions for the impedance switch, I did not get a manual with the purchase.
Thanks in advance.
Bob

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Thermioniclife on July 27, 2021, 11:04:53 AM

Yeah do not try to guess, if the whole key is broken off you can use these.
https://www.tubesandmore.com/products/keyway-replacement-piece-octal-tubes
The heater pins are 7 and 8, and these are the only 2 pins that have continuity so do search regarding tube pin numbering
and press the new key on so the key is in between pins 1 and 8

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Thermioniclife on July 27, 2021, 11:10:33 AM

I realize that my reply is somewhat cryptic at best.
go to this link and it makes it clear. use a meter set to ohms and the only 2 pins that show continuity are pins 7 and 8
then it will be obvious what to do.
http://tdsl.duncanamps.com/show.php?des=6DN7
Can't help with the impedance switch.

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: 2Bornot2B on July 27, 2021, 12:15:19 PM

Thanks that will get me started.

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Thermioniclife on July 27, 2021, 12:29:21 PM

You can mark the base of the tube between pins 1 and 8 and be careful to align the line up with the keyway on the tube socket.
And no need for the replacement key.

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Paul Joppa on July 27, 2021, 01:06:14 PM

If it's the stock impedance switch (no longer in production) then the switch positions are marked on the printed circuit board. With the writing right side up,.

Both switches up = 32 ohms
left switch down, right up = 16 ohms
left up, right down = 8 ohms
both down = 4 ohms

The third switch selects balanced outputs or unbalanced outputs

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Adrian on July 27, 2021, 01:22:03 PM

Quote from: Thermioniclife on July 27, 2021, 12:29:21 PM

You can mark the base of the tube between pins 1 and 8 and be careful to align the line up with the keyway on the tube socket.
And no need for the replacement key.

Yep, I did this with the broken pin on a 6080.

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: Tubegopher on July 27, 2021, 02:10:23 PM

Bob, I agree with Thermioniclife (hope I spelled that right) that you can just mark in between the 1 and 8 pin on the base of the tube and then line it up with the keyway on the socket.
However, I do have a bunch of the guide pin repair pins and would be happy to mail you one if you want to install it. It just makes it easier in the future if you remove the tube for any reason.
You can send me a private message to my email if you want one. I don't know why the envelope display does not show up, but if you place the mouse on the MSN "butterfly" and leave it there a few seconds, my email address will pop up.
Regards,
Don (Tubegopher)

Title: Re: 6dn7 with broken key on bottom; impedance switch positions
Post by: 2Bornot2B on July 28, 2021, 03:05:31 AM

Thanks to all the help is very much appreciated.
Bob