There are schematics on my website that might help when you get to
troubleshooting the amp.
http://audiosystemsgroup.com/publish.htm
Ron's suggestion to start by disconnecting the HV line is a very good
one. If the fuses don't blow, it's either in the power supply cabinet or
in whatever is powered from the 28V line. If it's in the power supply,
one of the first things to look for is charring on one of the circuit
boards. That happens with certain shorts in the RF deck, and you'll have
to repair the boards.
An obvious question -- any symptoms BEFORE it blew the fuses?
And another observation. These units WILL blow 20A fuses for no obvious
reason, and then work fine for months when they are replaced. I've never
figured out why. One of my 425s has done that every few months for two
years, and I've never done a thing to it but replace the fuses (I did
replace a vacuum relay and some of the filter caps three years ago when
I got it). That amp gets HEAVY use in contests, at full rated power.
73, Jim K9YC
73, Jim K9YC
|