Fisher Model 400 FM Stereo Receiver (1964)
If you're familiar with tube audio,
the name Fisher needs no introduction. Named after its founder and guiding
light, Avery Fisher, the company began in 1945 and produced some of
the world's best-performing and most elegantly designed high-fidelity
equipment during the 1950s and 1960s. The Model 400 FM receiver shown here
was manufactured from 1964 to 1968. Some tube enthusiasts rank
it as one of the finest FM receivers ever made.
I got this set in a trade. I had obtained a Fisher 500-C receiver some
months earlier, but it was missing its case and developed some
problems. When I got a chance to trade my non-working 500-C
for this working 400, I swapped without hesitation. Purists may
disagree on fine points, preferring one model over the other, but
to the average Joe, these receivers are basically equivalent. And I
wanted a good FM receiver for everyday use, so gaining a cabinet
was a distinct bonus.
Description
The 400 closely resembles the Fisher 500 and 800 series receivers
of the 1960s, with a brushed metal faceplate and brass-faced
knobs. On the left side of the dial, you can see the famous Fisher
bird logo, with a musical note in its beak.
(By the way,
the dial glass is not cracked, as might appear from the
cabinet photo. The light and dark areas in
that photos are reflections from the
table the radio is sitting on.) The wood veneer cabinet has a gold metal
grille at the back, providing extra ventilation for the audio output tubes.
The front view shows the 400's straightforward
controls, with five round knobs for tuning, power/volume,
left-right balance, treble, and bass. A sixth round knob selects among several
functions: tape aux, FM mono, FM stereo with filter, FM stereo, phono stereo,
phono mono, and tape head.
Slider switches control the tape monitor, speaker on/off,
high-frequency filter, and loudness contour circuits. A stereo headphone jack
is located between the two pairs of slider switches.
The front view also shows the audio transformers, a pair of big black
items in the center, as well as the even larger power transformer to the
right. All this "big iron" makes the 400 darned heavy. If you have to lift
the bare chassis, keep in mind that most of the weight is in the back, and
be careful not to mash the little plastic tuning pulley, which is mounted
near the chassis edge, right at the spot where'd you naturally want to
grip with your hand.
Almost every Fisher of this type has lost one or more of its little brass
knob caps, and this one was no exception (see the lower left knob). When the
glue dries out, the caps fall off. I obtained a replacement cap from a
company which advertises on eBay.
On the right side of the dial is a single "magic eye" tube that indicates
signal strength. Even though eye tubes are becoming scarce, I think
they're a lot more fun than modern meters with flopping needles.
Perhaps I'll do a page on magic eyes some time. You can read about a few others
in these pages: Motorola 10T28M,
Crosley 146CS,
Philips B5-X-34-A, Telefunken Gavotte.
In the rear view, you can see this set's many
input and output connectors.
The speaker terminal, located near the center,
lets you select 4-ohm, 8-ohm, or 16-ohm speakers. A single RCA-type jack
in the center lets you connect a single, monophonic, "center channel"
speaker. The antenna terminal appears to the left. Next to it are two
outlets for powering tape and phono equipment. To the right are six pairs
of RCA-type jacks labeled tape head, phono low, phono high, record out, tape mon,
and aux tape. Located directly above them, on the upper chassis surface, are
four more connectors (here, bridged with jumpers) for connecting a Fisher K-10
"Spacexpander" reverb system.
Also visible in the rear view are the receiver's four audio output tubes,
separated from the output transformers by a metal shield for heat protection.
The 400 uses all-glass Novar type 7868 tubes in a push-pull configuration.
The 500 and 800 series use 8-pin 7591 tubes. Both types are scarce and
expensive, running anywhere from $20 for used tubes to $50 or more for
a NIB ("new in box") tube. The tubes in my 400 are all original Fisher
stock.
The under-chassis view gives you an idea of
the model 400's complexity.
Repairing one of these—particularly, aligning
its complex FM tuner—is not a job for the faint-hearted. Mine appears
comparatively untouched. The only obvious repair is that the old selenium
rectifier has been updated with a more reliable silicon bridge rectifier.
As you may have read elsewhere in this website, selenium rectifiers should
always be replaced unless a set is for display purposes only. They
can start fire and emit a horrible stink when they fail, and the replacement
parts are extremely cheap.
Fishers of this type also used the newly-developed Nuvistors
in their patented Golden Synchrode FM front end. A Nuvistor is a miniaturized
tube in a small metal can. About the size of a pencil eraser (or an
early transistor, for that matter), Nuvistors couldn't compete with
transistors, and were soon supplanted in the marketplace. They are also
becoming somewhat hard to find, so if you have one of these sets, it's
not a bad idea to pick up a couple of spares.
(To be honest, I don't remember seeing the Nuvistors on this chassis, last
time I looked. In the place where they were located on my 500-C, the
model 400 had a single tube. Possibly they were relocated for some reason,
or perhaps my 400 is an early model that simply didn't use them.)
Restoration
This receiver did not require much work other
than cleanup. The cabinet was dull and very dirty, so I first cleaned it with
paint thinner and a soft rag, to remove all traces of old grime and
furniture polish. Next, I applied walnut-colored Minwax to even
out the color. If you let the Minwax settle in for a couple of minutes, then
wipe off with a soft rag and buff it dry, it stains any small scratches to
the original color without changing the overall color of the piece.
The gold-colored metal ventilating grille at the back had a few small
spots of surface corrosion. It's not the kind of thing that you can
polish away, so I sprayed on a coat of gold paint that perfectly
matched the original color.
The chassis also showed the usual amount of dust and grime. After cleaning
it with Fantastik household cleaner, I shined up the aluminum tube covers
and other prominent metal areas using Mother's Mag & Chrome Polish. Mother's
does a great job on aluminum and cadmium-plated parts.
After removing and cleaning the faceplate and knobs,
I also pulled out the dual dial lamps for cleaning. These lamps
are quite unusual. Looking more like fuses than pilot lamps, they
are long and slender, with a metal connector at each end. One side of
each bulb is painted white, to
reflect more light onto the dial. The bulbs are mounted so that they shine
through the ends of the dial glass, as well as slightly onto the dial
backplate. The dial lettering seems to glow against a softly lit
background, a beautiful and sophisticated effect.
When I tested the four 7868 audio output tubes, one of them
tested weaker than the other three. It is the leftmost tube
in the rear view,
and you can see that its top is lighter than the others.
Despite testing somewhat weak, the tube still performs well. Swapping it
into different socket positions, I was not able to detect any difference
in the receiver's sound. These tubes are becoming harder to
find, however, so I'll buy a fresh one for everyday use, and keep this
weak one as an emergency spare.
These receivers have a metal bottom plate, fastened with a few sheet metal
screws. Turning the set over and removing the plate, I was then able to
spray De-Oxit into the controls to clean and lubricate them.
The power-supply rectifier, as mentioned above, had already been replaced.
It is also common practice to replace all four of the Mylar audio coupling
capacitors in Fisher receivers. In mine,
one of the four audio couplers looked much darker than the others,
indicating possible failure. I replaced it with a new capacitor, although the old
unit still tested at the correct value.
The Fisher Doc recommends a few additional modifications for sets of this
type, aimed at improving performance and reliability. You can read more
about those procedures in my Fisher 800-B page.
One of these days, I'll haul the 400 down to the workshop and give
it the same tuneup.
Final Thoughts
Designed for discriminating listeners, it's not surprising that this
set performs very well. I
can clearly receive some FM stations which are unlisten-able with other
sets, and the audio quality is superb. It's so good, in fact, that I find
myself listening to types of music which I don't ordinarily enjoy! My
Philips B5-X-34-A runs a close second for
FM sensitivity, but it can't match the 400's powerful audio.
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