Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Applemacman on March 23, 2025, 08:11:21 PM
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I recently changed the chassis of my bottlehead crack as I wanted it to match the chassis of the riaa amplifier I built. My Bottlehead has the speedball installed. All was working without issues before changing the chassis. Now I seem to have an issue as one of the LEDs on the 12au7 tube doesnt light up, however the other one does. So im wondering if someone could help me Ive posted the voltages below:-
Pin. Vdc
1. 0
2. 95.4
3. 0
4. 49
5. O
6. 73.5
7. 156
8. 0
9. 156
10. 0
Speedball readings
Pin. Vdc
AO. 73.7
OB. 96.7
G. 0
B+. 155.5
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Pins 2 and 4 in the Crack are connected by a wire, yours are different by 50V, so they can't be.
Pins 7 and 9 are above pins 2 and 4, which also doesn't seem possible.
Pin 6 is showing DC voltage, so it's either not connected to the headphone jack, or there's a wiring issue at the headphone jack.
The Speedball readings don't match the terminals they wire to, so again, this is like the 2 and 4 being wired together but showing different voltages.
This is either a lot of mistakes, or a lot of solder joints that aren't solid.
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Seems strange to me since i only changes chassis and it was ok before the change. However thanks for the response I will go through this and recheck it late this week and report the results. Thank you for the advice
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I don't know what "only changing the chassis" means. Did you just remove the amp from its wood base and put it in a different wood base?
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Yes I removed it frim the wooden chassis and put it into a metal chassis that matches an RIAA valve amp I built. I had to cut a few wires and rewire them after relocation. However even though Im sure I followed and double checked the correct paths for these wires, I will go over it again this weekend.