Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: murpha77 on May 23, 2015, 06:45:08 AM

Title: Crack Voltage Check [solved]
Post by: murpha77 on May 23, 2015, 06:45:08 AM

Hi All

I have just completed the kit and have passed the resistance check but unfortunately fail the voltage check.

1: -0.93
2: -0.91
3: 0
4: -0.91
5: -0.93
6: 0
7: 0
8: 0
9: 0
10: 0
11: -1.2
12: 0
13: -0.92
14: 0
15: 239.2
20: 0
21: 239.2

A1: 0
A2: 0
A3:0.8
A4: 0
A5: 0
A6: -0.9
A7: 0
A8: 0.8
A9: 0

B1: -0.9
B2: 0.8
B3: 0
B4 -0.9
B5: 0
B6: 0
B7: 0
B8: 0

Both valves light up (the 12AU7 in two places) however the LEDs don't.

I have done the gross error checks of checking the orientation of the capacitors, tube sockets, LEDs and the leads on the multimeter (which is why the negative readings don't make sense).

Any help is greatly appreciated.

Cheers

Title: Re: Crack Voltage Check
Post by: Paul Birkeland on May 23, 2015, 07:21:05 AM

T15 and T13 are connected with a 270 Ohm 5W resistor.  Yours is most likely not well soldered.  I'm also not so sure about the solder joint on 12L. 

Is the upper ground lug on the volume pot soldered?  (If it is soldered, try holing the iron on it a little longer to get the solder to flow)

Title: Re: Crack Voltage Check
Post by: murpha77 on May 23, 2015, 08:14:50 AM

That was a quick reply!

You're right with 12L and the upper ground lug - they weren't soldered at all. Feel a bit silly missing those, a fresh set of eyes is always good!

The 270k ohm resistor is between terminal 12U and 13U (bottom of page 30 of the instructions), not 13 and 15 as you stated. Which is correct?

Title: Re: Crack Voltage Check
Post by: Paul Birkeland on May 23, 2015, 08:18:53 AM

Quote from: murpha77 on May 23, 2015, 08:14:50 AM

The 270k ohm resistor is between terminal 12U and 13U (bottom of page 30 of the instructions), not 13 and 15 as you stated. Which is correct?

Quote from: Caucasian Blackplate on May 23, 2015, 07:21:05 AM

T15 and T13 are connected with a 270 Ohm 5W resistor. 

We are referring to two different resistors.

-PB

Title: Re: Crack Voltage Check
Post by: murpha77 on May 23, 2015, 08:21:47 AM

I've just soldered the joints and now know what resistor you were talking about... Doh, engage brain before typing

Title: Re: Crack Voltage Check
Post by: murpha77 on May 23, 2015, 08:32:39 AM

Another Crack is alive. Thanks for the quick reply and help. Time to enjoy it and start the speedball kit.

Cheers