Bottlehead Forum

General Category => General Discussion => Topic started by: RNovus on May 14, 2021, 09:46:04 AM

Title: Crack 1.1 not working
Post by: RNovus on May 14, 2021, 09:46:04 AM: This is a new build. Just completed yesterday. One LED is out on A3. Voltage on terminal 5, 143v. Resistance checked out OK. Thanks for your help.
Title: Re: Crack 1.1 not working
Post by: Paul Birkeland on May 14, 2021, 03:52:50 PM: How is the solder joint at A4? Can you carefully measure the voltage at A3? Whatever you do, don't fixate on the LED itself being out and don't endlessly resolder it. There are many causes for this issue and it often isn't the LED itself.
Title: Re: Crack 1.1 not working
Post by: RNovus on May 15, 2021, 09:42:17 AM: A4 solder joint looks good. A3 voltage is 0.
Title: Re: Crack 1.1 not working
Post by: Paul Birkeland on May 15, 2021, 03:50:13 PM: Are you 100% sure both halves of the 12AU7 are glowing?

The 0V at A3 means that you either have half a dead 12AU7 (they very, very rarely just suddenly die on one side), or you have a bad solder joint that isn't allowing half of the 12AU7 to draw appropriate current. Perhaps posting some photos of the build around your 9 pin socket would be helpful.

-PB
Title: Re: Crack 1.1 not working
Post by: RNovus on May 20, 2021, 06:34:50 AM: Yes, only half of 12AU7 is glowing. Hereâ€™s some pictures. Hope they they shed some light. Thanks for your patience.
Title: Re: Crack 1.1 not working
Post by: Paul Birkeland on May 20, 2021, 06:58:34 AM: The green wire around A4/A5 does not look like what's in the manual. That is really the only cause of half of the 12AU7 not lighting up.