Fisher 500c Tube Receiver Noise

Meaudio1

AK Subscriber
Subscriber
My Fisher was working perfectly until I moved the unit and it sat still for a week. It still sounds great except when I turn the unit off I get a whisting sound out of the right channel. I hope this is a simple fix and I would not want to hurt my speakers. Any help or suggestions appreciated.
 
Try unplugging it instead of turning it off with the switch.

This is to isolate what the problem is not.
 
Could be a dirty tube socket. Clean 'em and make sure the tubes are seated solid!

A 12AX7/12AU7 tube will cause a squeal in either channel if it has gotten jarred around!
 
I cleaned all tube sockets by working the tubes in and out and then checked all tubes for proper seating and , so far the noise is gone. Unit sounds great with my recently refoamed Proac Studio ones. Thank you all for your advice.
 
After a night of great listening, I thought the problem was gone. When I turned on the unit today, I heard a light hum out of the left channel. I rechecked speaker terminal conections and again, checked for proper tube seating. I also pulled out the 7591's(Fisher Branded) and worked them in and out a few times to clean the sockets. I then turned the unit on again and it blew its fuse. I then went to Radio Shack and got another fuse. The unit turns on but there is a terrible loud hum out of the left channel. No doubt this is a terrific sounding unit but I do not know what to do as it was recently serviced. I don't understand how everything could go to hell in a handbasket that quickly. Using the 500c with my reconditioned Proac Studio Ones, I finally had the sound I was looking for. Is there an easy fix for this or am I in tube hell? Any help is sincerely appreciated as I miss it already.
 
You are not in tube hell.

If it was recently serviced, and not by you, is the service warranteed? Also, did you really get the feeling that the servicer was comfortable with the unit?

This isn't like modern stuff where, for the most part, you toss it when it breaks. Have faith.
Oh, and by the way, if you can do process of elimination work yourself, you may get at least part, if not all, of the way to resolving your own problem.

With the tube forum open, on the top, look through the tube amp stickies, and then use the forum search tools near the upper right and search on troubleshooting.
 
I have emerged from tube hell and entered tube heaven again. The problem was because of an old and defective 7591 which caused two resistors to short out. I just got the unit back yesterday from RHB Sound Dezign in Churchville, PA. The unit never sounded so good. I highly reccommend them as they are Class A, friendly and quite reasonable. I would also like to thank all who responded to my thread in this forum for their advice. This unit's match to my Proac Studio 1's great. Now it is time to look for a cabinet again. My preliminary research seems to show that getting an old beat up original cabinet is not the way to go as they seem to cost too much money. I am thinking of ordering from Mcintosh Cabinets.com as I beleive it is money much better spent. Wondered if anyone here has any experience with their woodwork. The pictures of these cabinets look wonderful but I have no experience with them. Thanks, Meaudio1
 
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