The Fisher 800T Receiver: advice needed

[Sparkie]

So my ignorant self recently acquired one The Fisher 800T Receiver from a gentleman who needed money a bit more then he needed to be able to rest comfortably at night. part of the game i suppose. unimportant at this juncture we must agree. so anyhow i now am in possession of one The Fisher 800T Receiver. The lights are on but nobodies home. The receiver produces no sound but at least it lights up. is very pretty to look at but there is part of me that craves for a bit more. The first thing i did when i noticed its deficiencies was to blow out the 40+ years of dust and to check for blown fuses. i do believe that i did locate 2 blown fuses. I had initiated a thread about this time in the D&S thread and i was instructed to ask the good people of the Fisher forum for advice. This did seem to be a fine idea so here we are. here are a few pics.

 

[Sparkie]

 

[larryderouin]

There are 500-TX / 800-T manuals in the AKdatabase here. Grab the cap service bulletin that addresses the AUTOSCAN. There is also a fusing service bulletin in the end of the Service manual that addresses the main fuses, and the fuses on the emitters at the output's. The fuses if I remember correctly are soldered in. You can either solder in new ones or mount fuse holders and go that way. The 800-T uses 4 fuses off the secondaries of the Power Transformers, and 4 fuses on the emitters of the output transistors. If it's never been in a FISHER Shop there should be 4 miniature 4A fuses on the emitters, 4 fuses on the power supply board, and 1 on the back panel for the mains. If it's been in a FISHER Shop that did the service bulletin, there will be 1 main on the back panel, and either 2 or 4 on the power supply board, and none on the output transistors. Use the schematics to figure it out. It's different enough from my 500-TX that unless I had it in my hands, I can't give you a more definative answer.

If the fuses are blown expect to replace the output's and possibly the driver transistors and other parts on the amplifier board. The power supply should be rebuilt as it sits on the underside and traps heat and cooks itself. It gets plenty hot under there.

Fix the problems 1st and then rehab it. The 800-T was the TOTL receiver for the 1969 thru 1972 model years. It's a Multi Voltage version of the 500-TX. The other thing that differentiates the 800-T is that a 2 button remote that activated the AUTO-SCAN remotely was standard equipment where on the 500-TX it was optional. Also the Faceplates were different in coloration. It's a great sounding unit with enough balls to play with the big boys of 80-100W.

 

[fred soop]

I'd start by disconnecting all loads from the power supply board and working on that until it works without blowing fuses and all voltages are correct. If the power supply isn't right, then all other work is a waste of troubleshooting. Next, try a DBT and connect the power amplifier boards, maybe one at a time. This is the most likely place to have major problems.