First time builder - failed voltage check [resolved]

[shroomalistic]

i checked the 12au7 for resistance
saw in another post to check a9 to a4 and a9 to a5
a4 is 0
a5 is 7

I did that too

[Paul Birkeland]

Is that the socket pins or the pins on the tube itself?

[shroomalistic]

tube its self,  its not zero,  there is just nothing on pin a4 to a9

[Paul Birkeland]

OK, zero would be the opposite of nothing, which is infinite. 

It's possible that the tube pins are a bit oxidized, and inserting them into a lump of steel wool a few times may clean them enough to restore operation.

[shroomalistic]

cleaned up the pins and still nothing on a4 to a9,  a5 to a9 still gives me 7

[Paul Birkeland]

It would be a good idea to try a different 12AU7 tube next.  Can you post pictures of the 12AU7 you have?

A bad 12AU7 still doesn't explain why you had such high voltage on terminal 9, but we'll address that when the front half of the amp is working properly.

[shroomalistic]

No clue when the nos tube will be here,  ordered it off ebay.

[shroomalistic]

so did i kill my tube?  Im a little worried now, should i put the new one in when i get it?

[Paul Birkeland]

It would be very difficult to damage that part of the tube. I would just give the replacement a go to see if both its halves light up.

[shroomalistic]

who would i contact to get another 12au7 tube?  Not sure whats going on with my ebay one.  If i can purchase or get a replacement from you guys,  I already have an order in for the LED's

[Larpy]

I don't know that BH sells tubes.  If not, and you're leery of ebay, I recommend the online vendor Tube World.  Not the cheapest prices, but every tube has its test results provided on the website.  That's rare.  The '60s Sylvania for $24.99 is what I'd get if I were you, but there are lots of good options for under $50.

https://tubeworldexpress.com/collections/preamp/12AU7

Tube World ships quickly as well.

[Paul Birkeland]

You can contact replacementparts(at)Bottlehead(Dot)com regarding this issue.  Be sure to post a link to this support thread with your request, along with your name and your order number if possible.

-PB

[shroomalistic]

so while im waiting for a new 12au7 to come in....  ebay guy still hasnt shipped,  Im getting a short on the trs jack at the resistors.  Should I  desoldier the resistors to see if they are bad?  I was looking at mouser for replacements but im not sure exactly what to get.  2.49k ohm 1/4w,  but will any of them work if they are threw hole?  I kinda want to start all over now just to be safe and now that i have the magnifying glass and all.  When I place my leads on both sides of resistors,  they read 0.00.  The 270k 1w resistor read OL but I think thats because it hooked up with the cap?

[Paul Birkeland]

The jack shorts the outputs intentionally when no headphones are plugged in, so there's no issue there. 

[shroomalistic]

new 12au7 is in

not sure if voltages are closer or not

1 - 147
2 - 168
3 - 0
4 - 168
5 - 148
6 - 0
7 - 146
8 - 0
9 - 147
10 - 0

a-3 13.1
a-4 3
a-5 3
a-8 13.8