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Bottlehead Kits => Crack => Topic started by: Bungwu on June 20, 2015, 06:59:21 PM

Title: Speedball - I goofed, but what did I damage?
Post by: Bungwu on June 20, 2015, 06:59:21 PM

So I had the Crack assembled and working and began the speedball upgrade

I am new to DIY soldering and circuits and I failed to recognize that the 2N2222A and 2N2907A transistors were different despite the big red warnings in the manual. I thought it was referring to the resistors, not transistors.

Anyways, a quick run down of what I did:

• one 2N2222A on the bottom right small PC board
• one 2N2907A  on the large PC board
• finished assembly, powered on...Tubes lit up, powered off to test voltage
• powered on to test voltage, noticed not all LEDs were on... little bit of smoke... powered off
• removed PC boards from Crack, checked all solder points(re-did a few)... reassembled, powered on, same  problem as before: tubes lit up, some LEDs on, and a  little bit of smoke
• removed PC boards again, noticed the swapped transistors
• desoldered the wrong transistors from the small and large board, soldered them in the correct location
• reassembled, powered on... and here is where it gets weird
• • Tubes turned on
  • LEDs on the smaller boards were all on
  • LEDs on the large  board were off
  • LEDs and Tube light begin to  slowly fade out until they are completely off
• I now can no longer get the Tubes or LEDs to power on

I am going to go ahead and assume I fried the 2N2222As and possibly the 2N2907As, is there anything else I should check and/or be worried about? 

Title: Re: Speedball - I goofed, but what did I damage?
Post by: Paul Birkeland on June 21, 2015, 06:51:55 AM

I would replace all of the transistors on all of the boards.

Generally a swap like this doesn't smoke the amp, so be prepared for additional diagnostics once everything is in its proper place.

-PB

Title: Re: Speedball - I goofed, but what did I damage?
Post by: Bungwu on June 21, 2015, 03:54:44 PM

Ok, I ordered the transistors.  I am guessing the bit of smoke was from a really bad solder point at 15 that I went back and fixed after my first set of problems.

Title: Re: Speedball - I goofed, but what did I damage?
Post by: Bungwu on June 25, 2015, 06:45:43 PM

Ok, I replaced all the transistors and the fuse and I have a different result now. 

-left most LEDs off
-bottom right small board's LEDs are both off. 

 I have no idea where to go from here.  Picture and voltages below.

Voltages
1   70
2   188
3   16   
4   188
5   185
6   0
7   110
8   16
9   186
10   0
11   16
12   0
13   187
14   0
15   206
20   0
21   222

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2Fgzfb2CV.jpg%3F1&hash=8af50df054497f9c6eda5cd434930451e17f811c)