Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: mbbarton on November 09, 2013, 10:05:31 PM

Title: Build issue; Hum but no sound [solved]
Post by: mbbarton on November 09, 2013, 10:05:31 PM

Just finished assembling Crack amp. 240V for Australia.

Deep low hum but no sound from either channel from a variety of sources.

Resistances all measure OK.
Some voltages measure 130% to 140% of manual specified ie 130V to 140V t; Terminals 1,5, 7,9, A1, A6, B1, B3, B4 and B6
A3 and A8 measure 15V and 12 V respectively rather than 1.5V

Joints checked and resoldered. Diodes and capacitors oriented correctly.

Any advice very gratefully received.

Title: Re: Build issue; Hum but no sound
Post by: Paul Joppa on November 10, 2013, 06:39:43 AM

The LEDs on the small socket are backwards or otherwise not functioning correctly. They aren't glowing visibly, are they?

Title: Re: Build issue; Hum but no sound
Post by: Paul Birkeland on November 10, 2013, 07:46:42 AM

Along with the LED's not glowing, are both the tubes glowing? 

Title: Re: Build issue; Hum but no sound
Post by: mbbarton on November 10, 2013, 09:57:53 AM

Tube's glow.
LEDs not glowing. Orientation is correct.
Output check at TRS shows voltage climbing to 5V then falling to zero.

Title: Re: Build issue; Hum but no sound
Post by: Paul Birkeland on November 10, 2013, 10:02:22 AM

Do you have the black wire going to the center lug on the 9 pin socket?

Any possibility of posting some build pics?

Title: Re: Build issue; Hum but no sound
Post by: mbbarton on November 10, 2013, 10:43:27 AM

Success!
Somehow missed the instruction for the black to middle of 9 pin Socket. works perfectly. sounds sweet.
thanks,
Michael