A local church has a rack of Peavey gear that drives their public address system. This unit had failed. A phone call to The Unbrokenstring Crew was all that was needed to get this unit onto the operating table.
Unlike a traditional guitar amp or stand-alone amplifier, this unit takes high level signals and buffers it to the loudspeakers. They are often used as a means to fill in or expand the coverage of an existing system.
And the inputs are daisy-chain-able.
This is, of course, the volume knob.
Here is a tour of the rear panel. The power switch is ‘center-off’ and, on this unit, does not switch the chassis ground to connect to one side or the other of the AC power line.
No tour of a rear panel is complete without a high-rez pic of the power cord.
And the name/rank/serial number part of our tour.
The AC line fuse was popped.
This is, correctly, a five amp slow blow unit.
Removing the front and rear panels permit access to all the electronics.
The chassis is attached to the rear panel of the unit. Surprisingly, the power transformer is NOT fastened to the wooden cabinet, but is also attached to the rear panel.
These filter capacitors are good and will not be replaced.
This unit has a shorted rectifier. New parts were secured, and are shown here. Although only one rectifier is bad, the other three are the same age and have experienced the same abuse, so they will all be replaced.
The new rectifiers are installed.
Funny thing is, the new fuse looks a whole lot like the old fuse, except it is not all exploded and burned and stuff.
The output from my radio is amplified to a larger signal using my Marshall Stack, to drive the input of the amp at the proper level.
This was the point when the neighbors called the cops to complain of the noise.
Thanks for reading all the way to the end!
CONTACT – David Latchaw EE
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