Original TRON arcade repair help!!!

[karatechamp999]

Hey guys recently acquired a tron upright 1981 - worked fine for awhile but was noticing a crackle in the sound - then it died (marquee light and coin door light, but no sound no video) so I opened it up and checked all the fuses - all were good except the 3/8 amp fuse on the 90412 power supply board, so I replaced it with a 1/2 amp fuse, turned it on and it worked again but noticed that the sound was all messed (double tones and random tones not playing) I then did a self-test and some of the sounds were not working and when I did a channel test (1-6), channels 4 and 6 did nothing and after a couple passes through channel 5 went too. played it a little more then the whole thing went dead again (which I assume the 3/8 A or shold I say the 1/2 A fuse blew again) - so before I put another fuse is this thing I was hoping one of you techie types would have some input on where I should start looking to solve this issue - much thanks in advance!

[jennifer]

    I would unplug  the monitor, take some power supply voltage readings and see if you get it to play blind.... That aux power board ( The one on the left side with the big transistors and heat sink) would be my next thoughts.