Transformers and condensers are not used below frequency 44, but a
length of resistance wire shunts each generator. Frequencies 44 to 48
have transformers only, while both transformers and condensers are used
for frequencies 49 to 91 except in the case of Model A consoles numbered
below 2179, which do not have condensers for frequencies 49 to 54 inclusive.
Two condenser values are used: O.255 mfd for frequencies 49 to 54, and
O.105 mfd for frequencies 55 to 91. The transformers are all different.
Each transformer is matched to its condenser and any replacements are
supplied as matched pairs by the factory.
There are several types of generators in use and the following information
will aid the service technician in identifying the console on which work is
being performed.
91 Frequency Generator:
Model A serial No. 1 – 2676 Model D serial No. 1 – 3143
Model B serial No. 4000 – 10549 Model E serial No. 8000 – 8663
Model C serial No. 1 – l247
The number of tone wheels on the above models is 91, and 5 blank wheels
are used to maintain the balance of the rotating units. There are twelve
wheels with two teeth, one to operate at each of twelve speeds, and
similarly twelve have four teeth, twelve have eight teeth, twelve have
sixteen, twelve have thirty-two, twelve have sixty-four, twelve have one hundred and
twenty-eight and seven have one hundred ninety-two. An assembly with a two-tooth
wheel also has a thirty-two tooth wheel which generates a frequency four octaves
above the other. The four and sixty-four tooth wheels go together. as do the eight
and one hundred twenty-eight tooth wheels. The twelve sixteen tooth wheels are
mounted with seven one hundred ninety-two tooth wheels and the five blank wheels. In
this last group the high frequency is not four octaves above, but is four octaves
less five semi-tones above the lower.
This arrangement gives a total of 91 frequencies that are connected to
corresponding terminals on the generator. and then to the manuals and
pedal switch. In all cases. as mentioned above. the generator must be
used with corresponding manuals and pedal switches and other types of
generators cannot be substituted.
82 Frequency Generator:
Model A serial No. 2677 – 2711 Model D serial No. 3144 – 17,074
Model B serial No. 10,550 – 17,074 Model E serial No. 8664 – 8739
Model C serial No. 1248 – 17,074 Model G serial No. 4101 – 7349
In the above consoles. frequencies # 1 to 9 have been omitted from the
generator, and only 82 generator terminals are used. Similarly, there are
only 82 tone wheels and magnets in the generator instead of 91. Blank wheels
replace the nine two-tooth tone wheels formerly used to produce frequencies
1 to 9.
4
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