Fisher 800-c problems

[Shrimp]

I just purchased a Fisher 800-c. Everything seems to work but the FM
reception and the fact that it seems to be running kinda hot. I was
wondering if anybody here new of any reputable service people in the
Los Angeles area. I'd love to find somebody local that was good with
older tube stuff becuase I can't really do the work myself. Thanks for
any info in advance!
-shrimp

[Gene Poon]

Shrimp wrote:

> I just purchased a Fisher 800-c. Everything seems to work but the FM
> reception and the fact that it seems to be running kinda hot. I was
> wondering if anybody here new of any reputable service people in the
> Los Angeles area. I'd love to find somebody local that was good with
> older tube stuff becuase I can't really do the work myself. Thanks for
> any info in advance!
> -shrimp

This won't help to find a servicer for your Fisher 800C, because I'm not
in the Los Angeles area and don't know whom to refer you to. Rather, it
is some knowledge from one who has owned the Fisher 500C, 800B and 800C.

A Fisher 800C WILL run "kinda hot," more so than any transistor
amplifier or receiver and even a lot of tube amplifiers. Those 7591
output tubes have small envelopes for the power dissipated and run even
hotter than some other power tubes. If the plates are not glowing red
when the receiver is fully warmed up, you probably have it running about
as cool as it ever will. If they do glow red, the amp is burning up
those tubes and it definitely needs service; when I have seen a
500C/800B/800C do that, the sound was accompanied by a low-level but
annoying 120Hz hum. Ultimately the amplifier was good for a moderately
priced receiver its era, but not up to the level of a Dynaco amplifier
of the same age and power rating, due to the way the output stage is
operated in the Fisher circuit. Actual continuous power output across
the entire 20-20KHz range is on the order of 20 watts per channel at
clipping.

Whatever you do, be careful about handling those output tubes. They are
expensive to replace. "CRASH, tinkle-tinkle" could ultimately mean over
$50 each. Be careful with the small tubes, too. If they are the
original tubes that Fisher put into the 800C when they built it, they
probably are Telefunkens that are in great audiophile demand, especially
the 12AX7 and 12AU7 types. Even if original "The Fisher" markings have
been rubbed off, a diamond shape molded into the glass at the base of
the tube is the giveaway of a Telefunken.

The FM section, after all these years, should have its tubes at least
checked and weak ones replaced, and sockets and pins checked and
corrosion cleaned out if necessary. There is also the probability that
it needs alignment of the IF, RF and Multiplex sections. That's not a
quick process, and it's not going to be cheap if it is properly done; it
takes me at least a good hour to do a complete and thorough alignment of
an old tube-type tuner. One can't just send a test signal through it
and tune everything to peak that signal; the proper way is to sweep the
passband with a low-distortion modulated signal and watch the bandpass
on an oscilloscope, aligning for the best and flattest response in the
IF stage, which might not yield the strongest signal but the
least-distorted one, coming out of the detector stage; a distorion
analyzer at the output of the detector confirms the adjustments. The
alignment process will also turn up any weak gain stages, particularly
in the 10.7 MHz IF section. Add to that the time it takes to take the
cover panels off and reassemble the piece afterwards, and the price to
do the job will probably approach $150 even if all the tubes are OK and
no actual repairs are needed. After all that, the measured performance
(sensitivity, selectivity, separation) won't be up to the standards of
modern solid-state tuners. But in a moderate to strong signal area,
with good tubes and a good alignment, it's probable that the Fisher's
tuner will sound glorious on a good clean signal, once it is done.

Good luck with your "new to you" Fisher 800C!

-Gene Poon

[Harry Lavo]

"Shrimp" > wrote in message
...
> I just purchased a Fisher 800-c. Everything seems to work but the FM
> reception and the fact that it seems to be running kinda hot. I was
> wondering if anybody here new of any reputable service people in the
> Los Angeles area. I'd love to find somebody local that was good with
> older tube stuff becuase I can't really do the work myself. Thanks for
> any info in advance!
> -shrimp

You may already know this, but there are two specialty companies that
specialize in repair and upgrading of Fisher tube gear. They are Bizzy Bee
in the Illinois suburbs of St. Louis, and The Fisher Doctor on Staten
Island, NY. That is all the info I have on them. While it would be nice to
think you could find a local who could do a good job, the odds are against
that. These two by reputation would not do a hachet job on the gear, but
would instead do the repairs and suggest other items that might well need/be
desirable as an upgrade. They both have great reputations. I own a tuner
done by Bizzy Bee (and then bought by me from the owner who had it done, and
the performance and workmanship are great).