Post by coleye on Sept 4, 2017 17:06:50 GMT
Hi, new to these boards but really hoping somebody can help. I have a GP12SMX 300 watt combo, loaned it to a friend who was running a small festival at the weekend. Apparently someone plugged the output from a bass head into the speaker out socket on the back of the amp (don't ask me how is could be confused) now the amp blows the mains fuse immediately it's switched on. I don't see signs of burning inside, but by what I've read on the net, there would seem to be a fair chance it could be the output transistors. Does anybody have any suggestions how to narrow down what the problem is? I'm gonna go now and disconnect all the boards from the power supply to rule out the transformer, then re-connect the boards one by one to try to isolate the problem, am I on the right track? Thanks for any help you can offer!
Update - disconnected all outputs from the transformer- fuse holds. Fuse still ok with cable reconnected to main pcb, so I'm assuming the fault is in the board with what I assume are the power transistors on the aluminium heat sinks. There's 3 on one heat sink and 2 on the other, is it worth just replacing them all and hope it was one of them? Any tests I can do to diagnose the problem?
Thanks again
Update - disconnected all outputs from the transformer- fuse holds. Fuse still ok with cable reconnected to main pcb, so I'm assuming the fault is in the board with what I assume are the power transistors on the aluminium heat sinks. There's 3 on one heat sink and 2 on the other, is it worth just replacing them all and hope it was one of them? Any tests I can do to diagnose the problem?
Thanks again