Hi all, I'm working on a Earth Module 440 Bass Head, direct rip-off of the Peavey Musician 400. When I first powered up, it hummed very loudly, then blew the fuse. I replaced the fuse, powered up, and now it's quiet. No sound at all. I measured no DC at the speaker jack, I've been using a schematic for the Peavey Musician 400 to get into the ballpark.
What would cause the hum to stop and no longer blow fuses? I suspect a power transistor, but I'd like to hear from more experienced folk.
I appreciate the help, thanks!
It could also be that you have a shorted output transistor and it burned open the emitter resistor that connects it to the circuit. Now that the resistor has acted like a fuse, the amp will power up to some extent without blowing the line fuse.
Additionally, are there any internal power supply fuses in there?
Try not to focus on what made teh one problem shift into anothwer problem. Just fix what is wrong.
Work with no speaker on it until we know it is stable and not producing DC. Check power supplies, no circuit works right without proper power supply.
Any shorted transistor you find, always check any associated resistors for opens.
Education is what you're left with after you have forgotten what you have learned.
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