My Crack build w/ manual queries

[denti alligator]

What should I try next? Should I remove the wire between A3 and A8 to start with, now that we've determined the LED is fine?

EDIT: Just double-checked all the wiring. Unless I'm overlooking something (possible, of course), I think everything is where it should be.

 

[denti alligator]

What are the chances the tube is no good?

 

[Doc B]

Why don't you measure the resistance across each half of the heater?

 

[denti alligator]

Why don't you measure the resistance across each half of the heater?

Can you tell me how to do this.

 

[Paul Birkeland]

Set your meter to Ohms, put the black probe on pin 9 of the 12AU7 out of the socket, then measure resistance between 9 and 4, then 9 and 5.

-PB

 

[Jimb0]

I reflowed A5 and A6. Still not working. Any other ideas?

Judging by the picture it looks like you didn't put enough solder on some of those terminals but it could just be the way I'm seeing it from the picture. I don't think it would hurt to add extra solder.

 

[denti alligator]

Set your meter to Ohms, put the black probe on pin 9 of the 12AU7 out of the socket, then measure resistance between 9 and 4, then 9 and 5.

-PB

You mean the tube itself? pin 4 is 4.38k; pin 5 is 7.5

(Seems like pin 4 is fluctuating. Now I'm getting in the 600 range. Yeah, every time I try it I get a new number, ranging from 300 to 47k. Meter works fine, as far as I can tell, measuring other things.)

The solder on the terminals is about how much I've used on my past three successful BH builds.

 

[denti alligator]

Does this mean I have a bad tube?

 

[Doc B]

Could be bad, but try cleaning pin 4 and measuring one more time.

 

[denti alligator]

Used deoxit. Still measuring all over the place.

EDIT: Guitar shop downtown has some Electro-Harmonix 12AU7s. Those any good? I might pick one up to hold me over till a replacement comes if it's really this tube that's bad.

 

[Doc B]

Yes, the EH will be fine.

 

[denti alligator]

If it works do you guys want to reimburse me for that instead of sending me another one? $15 I think. Or would whatever you send me be better?

 

[Paul Birkeland]

You can try an EH 12AU7, just to rule that out.  Also, you mentioned reflowing A5 and A6, it's A4 and A5 that make the tube glow (and A9).

 

[Doc B]

If you would like a replacement tube we are happy to send one. We are not able to reimburse for the purchase of a tube from somewhere else.

 

[denti alligator]

Yep, it was the tube! Popped in the EH 12AU7 and both LEDs are glowing. I'll go check voltages right now.

And the voltages are now right! So I did the build right to begin with, which makes me feel a little better. I'll contact Eileen for a replacement tube.

P.S. Are the tubes tested before being sent out, and if so does that mean this one was damaged in transit? (Just curious)

 

[denti alligator]

And it sounds lovely!

 

[Jimb0]

Great to hear! Enjoy your Crack my man!