Hartke b120 bass amp....not stable blows new output transistors and drivers ...what do you think ?

SOURCE: amp blows fuses

The fuses are there to protect the internals of the AMP.....
Please check that the correct fuses are installed......
if the incorrect ones are installed then a fire may develope...

There should be a manufacturers lable on the external chassis that details the fuses to use....

Fuses now days can be slow blow or fast blow....so the correct fuses must be used.....dont increase the fuse rating past the chassis panel label...but make sure they are correct...if they are correct then the amp needs a service to determine where the peak loadings to the power supply are originating from...

Some one may have installed incorrect fuses in the past...

Cheers from YUBEUT

SOURCE: amp : sansui au11000 blown transistors on driver board

Sometimes just replacing the outputs that have shorted are not enough to complete the repair of a main amp...this is because sometimes there is an intermittant or full failure in the bias circuit. Typically the Bias POT is the culpret.....when these pots get dirty or fail, the bias current ramps up way too high and then the Output transistors blow.......always replace the POT as part of the repair.....also check the bias varistor (Diode Stack) as these can open up after the first failure. Always pay attention to the bias circuit as this is critical to completing the repair properly....bias current adjustments can be made by measuring the voltage accross the Emitter Resitors connected to the Power Transistors...should read about 10 millivolts. The MJ15024 and MJ15025 Outputs are perfect replacements for Your Power Amp...I use them as well. Your tech probably just touched the bias pot, and that was all it took to make it fail (Open up)..If he was savvy, he would have replaced that POT before Touching it.

Hope this info helps....

Eric

SOURCE: Studiomaster 900E power transitors

read through this thread and you should be able to get a schematic

http://www.diyaudio.com/forums/showthread.php?threadid=140776

SOURCE: I need to find output transistors for a Rockford amp

Call rockfor fosgate and ask if they sell component parts to public, if not, ask who the their component manufacturer is, maybe you can get it directly from them.

Testimonial: "That's what I am doing right this second!"

SOURCE: speaker blow out with 34vts

Well, this may take some work, but do you have a schematic for the unnamed mystery amplifier?
If so, trace the voltage back to the op-amp chip that's sitting with V+ on it's output with no input, and you`ve found the problem!
Otherwise, if you have an oscilloscope, with no speakers attached, trace the incoming signal until it turns to a DC voltage or til the signal starts riding on a high or low voltage.

Oh, another thing to check, there's usually a couple high wattage low impedance resistors between the power transistors (unless it's a hybrid chip). If one of those resistors opens up, you can have this issue.