Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: meffisto on February 02, 2020, 10:01:20 PM

Title: wrong voltages and led not working [resolved]
Post by: meffisto on February 02, 2020, 10:01:20 PM: Hello guys,

I come to you since i cant use my crack speedball anymore.

I build it last year and listened without anyproblems for months.
I upgraded to speedball a few months laters and all was still ok at the beginning, voltages ok and sound ok.

untill the day something begin to go wrong, i lost one channel after a few minuts listening..
I toke the voltage and i got that:

OA 53v
OB 83v
G 0v
B+ 90v

and i got a led not working on speedball card, see the picture.

What could i do to find the problem?

Do i need to take more valtages?

thank you very much for ur help, i cant solve this alone..
Title: Re: wrong voltages and led not working
Post by: Paul Birkeland on February 03, 2020, 04:19:56 AM: If you pull the 6080 tube and run the amp with just the 12AU7, what are the I and O voltages on the small PC board up front?
Title: Re: wrong voltages and led not working
Post by: meffisto on February 03, 2020, 10:47:41 AM: Quote from: Paul Birkeland on February 03, 2020, 04:19:56 AM
If you pull the 6080 tube and run the amp with just the 12AU7, what are the I and O voltages on the small PC board up front?

Hey Paul, thank you for ur answer!

I removed the 6080 and get the voltages.

It is really strange since the voltage is not stable.

OA 80V first minutes then 230
OB 80V first minutes then 230
IA 230
IB 230

The first minutes the PC board's 4 leds are lighting then they all shut down.
Title: Re: wrong voltages and led not working
Post by: Paul Birkeland on February 03, 2020, 11:16:19 AM: When the O voltages pop up to 230V, is the 12AU7 still glowing?
Title: Re: wrong voltages and led not working
Post by: meffisto on February 03, 2020, 11:17:46 AM: Quote from: Paul Birkeland on February 03, 2020, 11:16:19 AM
When the O voltages pop up to 230V, is the 12AU7 still glowing?

Yes it is but all the leds are not.. on the socket and on the board.
Title: Re: wrong voltages and led not working
Post by: Paul Birkeland on February 03, 2020, 01:25:59 PM: Can you carefully measure the DC voltage on either A3 or A8, whichever is easier.

-PB
Title: Re: wrong voltages and led not working
Post by: meffisto on February 04, 2020, 08:09:33 AM: Quote from: Paul Birkeland on February 03, 2020, 01:25:59 PM
Can you carefully measure the DC voltage on either A3 or A8, whichever is easier.

-PB

1.5V on A3
got 80V on OB again since 10 minutes now :o
all 4 leds on small PC board are on
the only led glowing on the other board is the one which was off on my first picture, 3 others are off

i really dont get it, yersteday the OB voltage poped up to 230 today it seems to keep 80.. and the leds keep lighting..
Title: Re: wrong voltages and led not working
Post by: Paul Birkeland on February 04, 2020, 09:35:01 AM: This is a classic symptom of solder joints that haven't been flowed out all the way. I would reheat every solder joint in the amp.
Title: Re: wrong voltages and led not working
Post by: meffisto on February 04, 2020, 09:02:07 PM: Quote from: Paul Birkeland on February 04, 2020, 09:35:01 AM
This is a classic symptom of solder joints that haven't been flowed out all the way. I would reheat every solder joint in the amp.

will do that and let u know!

thank you :)
Title: Re: wrong voltages and led not working
Post by: meffisto on February 09, 2020, 09:47:05 AM: I have reheated every solder joints on and around speedball.

Everything seems ok right now ;D
I can enjoy my crack again!

thank you Paul!