Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: mlopez on May 20, 2021, 01:46:15 PM

Title: Checking in on Crack Voltages [resolved]
Post by: mlopez on May 20, 2021, 01:46:15 PM

I built my kit a couple of months ago. I had some trouble that developed overtime with cracking, so I reflowed all the joints. It didn't seem to help, but I discovered there was something loose with the headphone jack or related. I replaced the jack and all the wires running to it. I took this opportunity to also upgrade the pot and the output caps. I already had there speedball installed. Everything seems fine now, no cracking, but I just wanted to double check I'm ok with the following readings:

My Voltage check today is:

1. 77V
2. 202V      high?
3. 0V
4. 201V      high?
5. 76V
6. 0V
7. 113V
8. 0V
9. 112V
10. 0V

big board
OA 112V
OB 113V
G  0V
B+ 201V

little board
OA 77V
IA 201V
B-A/B 0V
IB 201V
OB 76V

Are the voltages at 2 and 4 high or are those normal post-speedball?

Thanks!

Title: Re: Checking in on Crack Voltages
Post by: Paul Birkeland on May 20, 2021, 02:16:30 PM

They are kind of high.  What's your AC powerline voltage?  How's your power transformer wired?

Title: Re: Checking in on Crack Voltages
Post by: mlopez on May 21, 2021, 06:29:44 AM

Thanks Paul. I went back and looked at the transformer wiring.  It should have been wired for 120V, but was wired for the <115V directions, so red wires on terminal 14 instead of 15. I corrected that and now my readings look better:

1. 81V
2. 184V
3. 0V
4. 183V
5. 79V
6. 0V
7. 108V
8. 0V
9. 107V
10. 0V

big board
OA 107V
OB 108V
G  0V
B+ 183V

little board
OA 80V
IA 183V
B-A/B 0V
IB 183V
OB 78V

Thanks so much for pointing me in the right direction. Did I do any damage running it for about a month mis-wired?

Title: Re: Checking in on Crack Voltages
Post by: Paul Birkeland on May 21, 2021, 06:59:51 AM

You may have shaved off some tube life, but nothing that you'll notice in the long term.