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I have a GK Backline 250 that keeps blowing fuses. I have already replaced r42 and c12 which were burnt up when I opened the case after the fuse blew. When I turned it on after replacing them, the fuse blew instantly. I have attached a schematic of the power amp section. Please help!
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SO get in there and start looking for shorted transistors. The output, the drivers, the bias transistor, go through them all.Education is what you're left with after you have forgotten what you have learned. -
This may sound stupid, but how should I go about doing this? My experience in repair is limited to replacing visibly burnt/bad components.Comment
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While physically burnt parts are obviously bad, it remasins that MOST bad parts don't look any different from good ones. We use our test equipment and our skill to find the bad parts. To test a transistor, we use the ohm meter. If the legs appear to be shorted together - a very low or even zero ohms between the legs - then the part can't be working. We then remove the part and verify the test when the part is by itself.
We use the schematic to identify the various parts and their relationships.
A burnt resistor never burns on its own, it is always caused by some other failure connected to the resistor.
I don't mean this unkindly, but if you don't know how to use a meter to identify bad transistors and diodes, it may be difficult for us to lead you through this.Education is what you're left with after you have forgotten what you have learned.Comment
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