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Fisher 500 TX Left and Right Channel Issue

J

jaba1971

New Member
Hello Members,

I have a Fisher 500tx that I use to listen to records with and I am now having a issue with the audio. The issue is that while listening the volume on 1 speaker randomly gets noticeably quieter than the other. This happens to either one or the other but never both at the same time. If I turn it off then back on both speakers come back up to the level I was listening at before the cut out occurs but then it happens again. The phonograph is a Gerard SL95B with a Empire 1000ze cartridge I do not know the make of the needle also the Speakers are Altec 604e's with the cross overs. Any Idea's???? Thank You!
 
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This sounds like either dirty controls and/or switches that need a good cleaning, or dried out coupling caps. There are other possibilities of course, but these are the most likely culprits. Has the unit been restored? Or is it still operating with the original stock components in it?

Dave
 
I was gonna say either the Balance, or Volume control is dirty, and with FM STEREO, the multiplexer board. Mine has an imbalance in FM STEREO only. I narrowed it down to the Multiplex board after cleaning, recapping all of the NON Tuner boards, and replacing all of the resistors that were out of spec on the same boards.

But it sounds like your switches and pots need to be cleaned 1st with DeOxit D-5 and Faderlube F-5(to rule them out), then if still there, troubleshoot the unit.
 
Thank You,

I should mention that sometimes it fades out and that its not a immediate cut out to the lower volume. The unit has been worked on in the past but its probably 99% original.
 
Larry what is the process for cleaning these do I just spray them out and is it dangerous to other parts of the unit?
 
Jaba: There's a sticky by Audiodon that lays out an excellent cleaning regimen including a piece on the switches and pots. It's a good read and I recommend it highly.

As to your specific issue: I like to stuff tissue paper around and underneath the switch or pot I'm working on. That'll help control the overspray and dripping. Look at the pot you're focusing on. You'll see a slot or opening where you'll notice metal contacts; turn the pot and you'll see how it functions. The metal gets gunked over the years and needs to be cleaned out. Stick the straw in the opening and spray. Don't flood it but give it a decent squirt. Work the pot back and forth several many times and squirt again. If you put tissue underneath you can sometimes see the gunk that has oozed out. Wipe up after yourself, I mean, well, you know what I mean.

You should really do this to ALL the pots and switches while you're under there. If you work with care and proper prep, the other components won't even notice :D
 
Don't try and remove the front panel unless you know how. The channel preset panel is attached to the front panel and the wires are short.

Removing the bottom will allow access to all the pertinent pots/switches.

Then do like notdigital said. Follow up the DeOxit D5 (cleaner) with FaderlubeF-5(lubricant). Do the push switches (Loudness, Low Filter, High Filter, Muting and the Autoscan up and down push switches.)

DO NOT DO THE 6 UPPER LEVEL SWITCHES/VARACTOR PRESETS with DeOxit!!!!!! If you have a need to clean them use CRC QD Electronics cleaner. Then let them dry overnight with a small fan on them.

Set aside an hour or so to do all this. 1st timer, let it sit overnight to dry and settle down.

Larry
 
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