Hi All, I want to make everyone aware of a wiring error that may be present
in some of the following amps AL-82, AL-1500. AL-1200. You can test to see
if your amp has this wiring error very easily. You have 2 fuses on the rear
of the amp. Remove the top fuse and turn the amp on and see if you get panel
lights and blower going. If so, your unit has the wiring error. If the amp
does not come on that is good. Now, replace the top fuse and pull the
bottom fuse and see if the amp comes on. The amp MUST NOT come on at all with
either fuse pulled with the other in place.
REASON: What could happen is you can blow a fuse and not know it, the HV
will go off, but the amp will operate normally otherwise, you could continue to
drive the tube with no plate voltage and that could cause problems if you do
not realize it right away. If you blew a fuse the whole amp should shut down
completely right away and if your unit has wiring error, it won't and could
lead to tube damage if prolonged.
THE FIX: Open up the amp and look at the fuse holders in the back, one fuse
holder will have 2 wires going to it on the line side of the fuse. One of
these wires (white in color) goes to the filament transformer primary, find
that
one and simply move it to the load side of the fuse holder, NOW...if you lose
this fuse, the amp will shut down completely letting you know right away
there is a problem.
Some amps are wired correctly and some are not. I can't seem to find any
trend for which amps are right or wrong except to give them the test.
73 Lou W1QJ
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