Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: JMac on January 22, 2018, 05:13:03 AM

Title: Lost Right Channel in Small Board Installation Step [resolved]
Post by: JMac on January 22, 2018, 05:13:03 AM

First time poster and tube noob...

First off voltages after small board install:
OA:  72.7
IA:   176
B-A/B:0
IB   175.8
OB:  72.1

As stated in the post title, lost the right channel after small board installation although voltages seem within spec. 

Background info.  Built the crack in June 2016.  Enjoyed it for a long time.  Installed an after market volume pot which was bad (long story).  Just switched back in original pot 2 weeks ago and had to replace the wiring from RCA jacks (for length).  Could not clean solder out of 3L with solder wick for fear of melting surrounding sires (bad eyesight), so all 3L connections are made at 3U.  Lost the right channel then.  Bad solder joint to the right channel RCA jack.  Fixed that, enjoyed for a couple of weeks before rolling in the Speedball upgrade.

Installed the small board, checked voltages - results above.  Gave it a try and right channel out again.  Changing balance to right channel only I can hear the ghost of music, but no crackling with volume, no volume change and no cutting in or out.  Tried some continuity testing for sound path from RCA jack through pot and tube sockets and found nothing, though I'm searching blind from lack of knowledge...


Any help appreciated

Title: Re: Lost Right Channel in Small Board Installation Step
Post by: Paul Birkeland on January 22, 2018, 06:01:15 AM

What voltages do you have at terminals 7 and 9?  The small board itself isn't the actual issue, but you likely have a broken wire or bad solder joint that is now making itself known.

-PB

Title: Re: Lost Right Channel in Small Board Installation Step
Post by: JMac on January 22, 2018, 09:59:08 AM

Thanks PB -

They are
97.7 at 7
98.3 at 9

fairly in line with the 100....

Title: Re: Lost Right Channel in Small Board Installation Step
Post by: Paul Birkeland on January 23, 2018, 03:53:11 AM

Yeah, your Crack is still functioning properly.  The loss of a channel in this case indicates a bad or unsoldered joint in the original build.

If you aren't able to spot it, you can download a 60Hz tone to play into the Crack and we can trace the signal to see where it's interrupted. 

Title: Re: Lost Right Channel in Small Board Installation Step
Post by: JMac on February 06, 2018, 07:25:35 AM

Bad wire from right RCA input to volume pot.  Thanks PB - Resolved.

Back in headphone Nirvana finally.  If Crack + 1/2 a speedball sounds this good, I cannot imagine what the mainline must sound like...