What Have I done? Shorted an amp?


I had two amps that were on (I know) and while moving one speaker connection to another amp, the speaker cables touched the other amplifiers case, sparked, and the amp that was touched, turned itself off, one of a pair Jeff Rowland Model 7, DAMN!

Now, it powers on but I get no sound coming out?

What have I done? At 140 lbs, I don't want to ship this thing around, if it is an easy thing?

HELP!!

Stressed, frustrated, feeling lame, and back to mono,

Dan
porschecab

Showing 1 response by marakanetz

In my case only output fuse will be blown if such thing take place. I know in Creek amps such event is fatal to an output circuit and even toroidal output transformer(sometimes to be on the safe side the time delay circuitry might be handy)

If changing the output fuse will not change things, here is the simpliest tip you can excersise:

Prior to this excersise I would suggest having a multi-meter and a handy book with specs for transistors set of impedance values between pins(that have to be studied prior in order to presicely detect the defected transistor).

Having the second mono-amp working, you should uncover both of them and compare-test both output stages meaning measuring resistances of output transistors while the both units are off. How you will detect an output circuit? Very simple: you should follow from your binding posts backwards and drow for yourself the points to compare-measure.

For example: you know that the input impedance of amplifier is much greater than the input 10x...100xKOhms VS. 10xOhms.
What if the output reading on your multimeter will show 300KOhms? -- It means problem occured probably with blown transistor.

My first experience on fixing audio/video gear was using an identical unit and the broken unit uncovered and measured. This can be called a "monkey work" but it works.