Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: supmate on December 02, 2013, 02:23:54 PM
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recently installed the speedball upgrade and did not get expected readings for voltage checks measurements for the right channel. when i measure terminals 5, I get around 57 volts instead of 75 volts. Looking at the circuit diagram i think the problem occurs at the node that the collector of the MJE-350 transistor is connected to. I think it maybe a problem with the MJE-350 transistor but I'm not sure. Unfortunately I shorted out the two red LEDs on the left (comparing voltage readings between both channels) in the process of trouble shooting. So I am going to have to order new parts.
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An often problem with this upgrade is that the center pin of the MJE-350 is the back of the transistor and sinks a lot of heat. IT takes longer on that pin to get a good solder joint.
Try reheating it.
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recently installed the speedball upgrade and did not get expected readings for voltage checks measurements for the right channel. when i measure terminals 5, I get around 57 volts instead of 75 volts.
Hmm, I would've tried swapping 12AU7's, or swapping the small green PC boards. It's possible that you have a 12AU7 with high emission on one side. If you did, swapping the boards would not move that voltage around.
I don't think you have any bad transistors (at least before your accident).