Matching Transformers
The matching transformer is used to match the low impedance of the generator and key
circuits to the high impedance amplifier input. It serves also, through taps on its
primary winding, to establish a series of intensity levels for the drawbars and
preset panel.
The following types of matching transformers have been used. In most cases they are
not interchangeable, and console serial numbers should be furnished when ordering
replacements.
1. Large-core transformer, used in Models A, B, BA, BC, C, D, and G. These were
enclosed in two sizes of shield cans at various times, but they are identical
otherwise. Two transformers of this type were used in Model E.
2. Large-core transformer with taps revised. Matching transformers in organs with
non-selective vibrato (Models BV, BCV, CV, DV, and RT) are slightly different from
earlier models in the number of turns to the first three taps. If a transformer in
an earlier organ is replaced by one of the newer type, any preset wires on preset
panel bars 1, 2, and 3 should be set to the next higher bar in order to make the
combination sound the same as before. For instance, combination 00 3543 111 with
the old type transformer would become 00 4544 222 with the new one.
3. Small-core transformers used in selective vibrato organs Models B-2, C-2,and RT-2
having preamplifiers code A, B and C. Two transformers are used in each organ, one
with large stack for the upper or swell manual, one with small stack for the lower
or great manual and pedals.
4. Revised small-core transformers with smaller stack and greater number of turns.
These are used in B-2 consoles serial number 42636 and above, C-2 consoles serial
number 42875 and above, and RT-2 consoles serial number 2381 and above (having
preamplifiers code D, E, F, G) and in B-3, C-3, RT-3, A-100 and D-100 consoles.
Because differences in the preamplifier input circuits will cause irregular
response, these transformers are not interchangeable with the previous type, unless
the preamplifier is changed at the same time.
OPERATION OF MECHANISM ON PRESET KEYS
In their basic construction the preset keys are identical to the playing keys.
Each has a plastic key mounted on a metal channel, pivoted in the rear and with a
guide toward the front to minimize side motion.
On the front edge of each channel of the 9 preset keys and 2 adjust keys, two flat
springs are attached, one 5/8" long of rather stiff material, and another
approximately 3/4" long of softer material. The softer long spring is sandwiched on
top of the stUf spring, nearest to the key. The cancel key has only one heavy spring
approximately 1" long.
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