Amp problem Ami F-120

I am working on an ami f-120. when i plug the amp in the 5ug tube gets
hot very quickly. really glows bright. changed tube and it did the
same thing. for some reason it seems to be drawing way to much
current. anyone have a idea whats bad in it. cat see anything wrong on
the underneath side. i took an amp out of another machine and it
worked fine so it would seem the problem is in the amp itself. any
help would be appreciated. thanks norm in missouri

On Sep 25, 4:25*pm, em pinball wrote:
I am working on an ami f-120. when i plug the amp in the 5ug tube gets
hot very quickly. really glows bright. changed tube and it did the
same thing. for some reason it seems to be drawing way to much
current. anyone have a idea whats bad in it. cat see anything wrong on
the underneath side. i took an amp out of another machine and it
worked fine so it would seem the problem is in the amp itself. any
help would be appreciated. thanks *norm in *missouri


Try this test; with the machine at-rest --turned on, other tubes
glowing but not playing, does the 5u4 still overheat? If not you
almost certainly have either shorted filter cap or output
transformer. The cap is the most likely due to AMI's stupid muting
design that shuts off the B+ voltage between -records-! thus the
filters take a hit each time a song plays.

There is an outside chance that the wiring to the relay, or it's
insulation has broken down, but the filter cans are prime suspect.

I have had a J-200 and still have an I-200 stereo and modded those
amps to not switch the B+ and connected a relay to the turntable motor
circuit to switch the amp on at the start of play.