Western Electric Hearing Aid Servicemaster/Hearing Aid Gainmaster
The Western Electric Hearing Aid Servicemaster (right) and Hearing Aid
Gainmaster (left) were made in 1950 by the Western Electric Co. of Kearny,
NJ. They functioned together as a single unit (had the same serial
number).
These repairman's instruments were made for testing and calibrating
hearing aids made by Western Electric between the years 1940 (hearing
aid Model 125) and 1950 (hearing aid Model 67).
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View of the Western Electric Hearing Aid Servicemaster showing the power
cord (right side) and the test probes (black & red) (bottom).
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Front view of the Western Electric Hearing Aid Servicemaster. The
Servicemaster pretty big unit. It measured 9" wide x 7⅛" deep x 15½" high (22.8 x 18.2 x
39.3 cm) and weighed a hefty 16 lbs 2.5 oz. (7.34 kg) without any batteries. |
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Top view of the Western Electric Hearing Aid Servicemaster showing the
heavy duty handle and a fuse holder (front center). The fuse is a
1/100 amp, 250 volt fuse.
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Close-up view of the top half of the front of the Western Electric
Hearing Aid Servicemaster showing the multi-range meter. The lowest
scale read from -25 to +6 decibels. The blue scale above it read from 0
- 5 milliamps. The orange scale read from 0 - 100 milliamps. The green
scale read from 0 - 2.5 volts. The red scale read from 0 - 50 volts. The
top black scale read in ohms. There were 5 resistance scales depending
on which button was pushed in. |
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View of the bottom half of the front of the Western Electric
Hearing Aid Servicemaster showing the various knobs, pushbuttons,
switches, etc.
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Close-up view of the upper part of the bottom half of the front of the Western Electric
Hearing Aid Servicemaster showing the various knobs, pushbuttons,
switches, etc. The knob in the top left corner was for zero adjusting
the meter. The middle one was for zero adjusting for reading resistance
in ohms. The knob in the top right corner was for setting the gain
adjustment.
Below these knobs were a row of 11 push-buttons. They are color-coded
to go with the colors of the appropriate scale on the meter (see above).
Note that there were 5 buttons for testing resistance with
multipliers of x1, x100, x1,000, x10,000 and x 1,000,000.
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Close-up view of the lower part of the bottom half of the front of the Western Electric
Hearing Aid Servicemaster showing 3 push buttons for testing 22½, 30 and
45 volt batteries. Below them are a row of 4 switches. The left switch
was for using internal or external batteries, next was for testing the
internal or external batteries, third was a receiver test/listen switch
and fourth, the power on/off switch. On the bottom row is a fuse, then
the black and red probe jacks, the power on light and the ground screw
post.
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Close-up view of the upper part of the back panel of the Western Electric
Hearing Aid Servicemaster showing the 5 spare fuse holders and
instructions. The yellow note reads, "Meter Fuses/ Special 1/200 amp
fuses/ See instruction manual"
The red note reads, "Note/Be sure to secure back cover of
Servicemaster with all screws to avoid damage to instrument in
shipment." |
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Rear view of the Western Electric Hearing Aid Servicemaster with the
back panel removed showing the
electronics (upper part) and the battery and battery wires (lower part).
The battery connections are shown on the side of the chassis.
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Upper rear view of the Western Electric Hearing Aid Servicemaster
showing the large power transformer (left) and the two tubes—6X5
(center) and 6SN7 (right).
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The B1 battery connection strip on the left edge of the chassis of the Western Electric Hearing Aid Servicemaster
is for an Eveready No. 741 battery.
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The B3 battery connection strip in the center of the chassis of the Western Electric Hearing Aid Servicemaster
is for an Eveready No. 770 , 22½ volt battery.
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The B2 battery connection strip on the right edge of the chassis of the Western Electric Hearing Aid Servicemaster
is for an Eveready No. ? dual voltage, 9 and 22½ volt battery.
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Lower rear view of the Western Electric Hearing Aid Servicemaster
showing the wiring to the front panel and the battery wires in the
foreground.
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Lower rear view of the Western Electric Hearing Aid Servicemaster
showing the 1½ volt No. 4F "A" battery connected, and the other battery wires
to the right.
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Close-up view of the top of the 1½ volt No. 4F "A" battery showing the 2-pronged
plug and socket.
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Close-up view of the labeled battery wires for the various voltages
of batteries used by this test instrument. From left to right they are labeled "B -", "B2 -22[½]", B2 -9", B2 +", "B3
+". (Note the second pair of wires [unlabeled] are the wires for the 1½
volt battery shown above.)
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The serial number of the Western Electric Hearing Aid Servicemaster can
be seen on the chassis located just in front of the socket opening on
the lower left front corner. The serial number was S150. Obviously
there were not very many of these units made. They quickly became
obsolete with the advent of transistor hearing aids that came to market
just 3 years later.
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The other "half" of the Western Electric Servicemaster was the Western Electric Hearing Aid Gainmaster.
It connected to the Servicemaster by a thick cable (see below).
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Close-up view of the plug of the Western Electric Hearing Aid Gainmaster
that connects to the corresponding socket on the Hearing Aid Servicemaster.
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Lower left side view of the Western Electric Hearing Aid Servicemaster
showing the socket that the plug (left) from the Gainmaster plugs into.
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Rear view of the Western Electric Hearing Aid Gainmaster showing the
cable to connect to the Servicemaster tucked away in the bottom.
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Close-up view of the nameplate of the Western Electric Hearing Aid
Gainmaster on the lid in front of the handle. Note that this device contained an acoustic test
chamber in the top.
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Close-up view of the top of the Western Electric Hearing Aid
Gainmaster with the lid opened revealing the acoustic test chamber.
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Front view of the Western Electric Hearing Aid Gainmaster. The
handle on the top served two purposes—as a carrying handle, and as a
means to open the acoustic test chamber lid.
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Front and side view of the Western Electric Hearing Aid Gainmaster
showing its slanted front face. The Gainmaster measured 7" wide x 7¼" deep x 6¾" high (17.8 x 18.5 x
17.3 cm) and weighed 6 lbs 1.5 oz. (2.78 kg).
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Close-up view of the note holder of the Western Electric Hearing Aid
Gainmaster. Note the date on the label (2-1-50) [February 1,
1950].
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Close-up view of the row of 5 push-buttons below the note holder on the
front of the Western Electric Hearing Aid Gainmaster.
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Close-up view of the bottom left corner of the Western Electric Hearing
Aid Gainmaster showing the connections for the Western Electric Model
134 hearing aid (1944) and the Model 125 (1940).
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Close-up view of the center section on the bottom front of the Western
Electric Hearing Aid Gainmaster. This selector knob (missing)
selected among 6 different Western Electric vacuum tube models of
hearing aids, namely—model 125 (1940), model 63 (~1945), model 64
(1946), model 65 (1947), and models 66/67 (1947/50).
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View of the Selector knob off the Western Electric Hearing Aid
Gainmaster showing its shape (before the knob went missing).
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Close-up view of the bottom right corner of the Western Electric Hearing Aid
Gainmaster showing the the sockets for the probe and black and red leads.
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Close-up view of the bottom right corner of the Western Electric Hearing Aid
Gainmaster showing the the probe attached.
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Battery holder used with the Western Electric Hearing Aid
Gainmaster. The battery holder could hold a 1½ volt "D" cell on
the top and plugged into a "B" battery on the bottom (see below).
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View of the underside of the battery holder used with the Western
Electric Hearing Aid Gainmaster showing the three-pronged "B" battery
plug for plugging directly into the top of a "B" battery.
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Close-up view of the battery holder used with the Western Electric Hearing Aid
Gainmaster showing the name "Western Electric" and the model number
"54A".
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The battery holder cord was fastened to the Western Electric Hearing Aid
Gainmaster so it didn't get lost. The other end had a three pin
plug for attaching to the hearing aid.
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Close-up view of the three-pin plug on the opposite end of the
battery holder used with the Western Electric Hearing Aid Gainmaster.
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