Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: LukeC on January 12, 2022, 10:20:40 AM

Title: Voltage issues across OA and OB
Post by: LukeC on January 12, 2022, 10:20:40 AM

Hiya,

I've had my crack w/speedball for 6 years now and it's run perfectly ever since I assembled it. Recently, I unplugged my headphones and plugged them in again when the crack was on and have had issues since, I had no audio through the left side at all and had a lot of noise through the right side. I found the LED from A3 to the central post on the 12AU7 socket had blown so I've bridged the gap with a wire temporarily but now I'm reading 45V at OA and 75V at OB. (With the blown LED OA was reading 173V) Do you have any ideas what I can try to fix this? I've tried different 12AU7s and 6080s to no avail.

Thanks in advance!

Title: Re: Voltage issues across OA and OB
Post by: Paul Birkeland on January 12, 2022, 10:23:15 AM

If you installed a wire in place of the LED, that won't work.

You can temporarily connect a wire between A3 and A8, however, and that may get you back up and running.

A common solder joint that tends to be problematic is where the black wires meet on the headphone jack, and I would suggest double checking that these wires are well soldered and secure.

Title: Re: Voltage issues across OA and OB
Post by: LukeC on January 13, 2022, 06:19:05 AM

Connecting the wire from A3 to A8 got the voltages back into the realm of normal, there's a 5V difference between the two sides so I've ordered a replacement LED that will hopefully remedy the situation, thanks for the help!

Title: Re: Voltage issues across OA and OB
Post by: Paul Birkeland on January 13, 2022, 09:27:55 AM

A 5V difference between OA and OB is OK.