Solid State Guitar Amp Forum | DIY Guitar Amplifiers

I have tested all components and found one bad output transistor, I replaced it and still get a blown fuse. anyone have the same problem?

You need to limit the current when you power up after repairs. A light bulb in mains line in series with the amp will do fine for this purpose. If some problems still exist (it is very typical that they do) the amp won't blow again due to them and you can continue on locating  faulty components you missed at the first time. If you do not limit the current draw you can easily wreck all the repairs you have performed with a single flick of a switch. All it takes is a single faulty component that takes down a bunch of others. Fuses are not fast enough to protect transistors so I'm afraid that you pretty much need to test all those semis again (even the ones you replaced). :'(