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Fisher 500c low headphone output.

B

bigdogsrule

New Member
Hi All,

I just picked up a Fisher 500c. It had extensive work done to it in April of 2015. This is the second 500c I've owned. What I discovered is that the headphone output level is very low. My last one was fine with the same headphones so I know something is amiss. Do any of you Fisher dudes have any idea what may be the cause of this?

Also, as was the case with my last 500c, the headphone left and right stereo signal appears to be wired backwards. It pans left instead of right and right instead of left. Is that something that is common with the 500c or have I just gotten lucky twice? :)

Thanks in advance!
 
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Big -- ALL of the Fisher vacuum tube stereo equipment that had a built in headphone jack were wired backwards from the factory compared to the standard today. That's because there were no standards back when this equipment was built, and they simply standardized the jack wiring during production to what became eh, the wrong way!

As for low headphone volume, they are driven off of (effectively) the 4 Ohm tap of the output transformers through a 330 Ohm 1W resistor in each channel. If the speaker volume is good and only headphone volume is low, then check the two 330 Ohm resistors to make sure they are the correct value or are not damaged in some way. If speaker volume is good, those resistors are about the only thing that can go wrong with the headphone circuit. On the other hand, if speaker volume is also low, then the problem exists elsewhere.

Good luck with it!

Dave
 
What headphones? And input impedance? Agree with Dave with regard to the wiring. Probably easiest place to swap them is right at the plug. And you can check the resistor's at the same time
 
Dave, the speaker output level is what it should be. I'll check the resistors. Thanks!

Larry, Sony 7506s and Sennheiser HD-280s. They worked fine with my last Fisher 500c and everything else I've used those and others I have with. Must be the resistors.
 
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