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I just got an NTE121 replacement transistor for an old 2N2148 that was in a guitar amp. It was the only part I replaced and now I have no sound coming from the speaker. I checked every component on the board with a multimeter and did not find any dead spots, including the new transistor. Is it possible that a new transistor could be dead out of the box? I have really only ever dealt with capacitors before.


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Did you try it outside the amp first? – clabacchio Dec 25 '12 at 15:18
Do you mean for continuity? – Mike Stumpf Dec 25 '12 at 15:26
Sure, it's possible. But it's more likely that either the new transistor is not a direct replacement (pinout might be different, etc) or that some other failure in the amp which lead to the original transistor failure, is still there causing problems. – Chris Stratton Dec 25 '12 at 15:31
Did you check power supply voltages are within spec? Including its ripple? – jippie Dec 25 '12 at 15:42
Sounds like a bad soldering/connection. – jippie Dec 25 '12 at 16:33
up vote 2 down vote accepted

Another transistor in the signal chain was causing the loss of signal..

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