Table of Contents
Advertisement
( ) In addition, turn on "Vibrato II". The intensity (or depth) of the vibrato
increases.
( )Turn on "Vibrato III" additionally. This causes the heaviest vibrato. By the way,
the two vibrato intensity switches II and III are effective only in conjunction with a
turned on "Delayed Vibrato" or " Contin. Vibrato':
( )Turn on yet "Slow Vibrato". The previously fast vibrato should slow down
about 40 %.
General Procedure in Trouble-Shooting of Switch Functions
All modes of operation of the various building blocks throughout the organ which
are controlled by a mechanical switch are activated as follows: The switch sends
a negative (-15 V D C) control voltage to the corresponding location. Since it is
irrelevant from where the control voltage originates we can also activate a
particular function with the help of our test wire.
Example: Suppose that the function "Slow Vibrato" does not work while all other
vibrato modes are operating properly. First, we trace the control voltage.
We find that the switch "Slow Vibrato" is shown in Fig. 59. The control wire is No.
14 5. The wire list states that the other end of wire No. 145 is connected to the
tone generator G 1, plug A, pin 3.
Using our test lead (extended with a piece of bare wire) we touch this pin on the
generator. There are two possible results, namely:
a) The vibrato does not slow down,
b) The vibrato slows down.
c)
In case a) the problem is located o n the tone generator board (though it was
tested; did you miss that test?). In case b) we conclude that the control voltage
does not arrive at the tone generator.
Where did it get lost? In the harness? That is easy to verify by touching the
corresponding pin of the switchbank (other end of wire No. 145). If the vibrato
does not slow down we have to assume that the wire you see emerging from the
switch bank is not the one arriving at pin A 3 on the generator.
More likely, the vibrato will slow down, giving rise to two new questions:
AM 079 (Part)
a) Is the switch "Slow Vibrato" defective?
b) Is the control voltage for the entire switch bank missing?
c)
Question b) can be brushed aside immediately since the other switches of the
same group do control their functions.
The last locations of the trouble are, therefore, the switch itself, the foil pattern on
the board US 1, or the diode in series with the switch.
Clip the positive test lead of your voltmeter (15 V D C or greater) to ground and
test the following points in the indicated sequence:
1) Switch bank pin "p m " (master control voltage for entire switch bank).
2) One of the two pins at the rear of the switch (no voltage = defective switch).
3) Pin a where grey wire (No. 145) is connected (no voltage = defective diode,
wrong polarity of diode or interrupted foil pattern). Also refer to Fig. 28 for layout.
It took us quite a few words to describe this procedure. We hope that you
understand the fundamental idea behind all trouble-shooting.
a) Identify the function that is not working.
b) Locate the "sender" of the control signal (usually a switch).
c) Trace the signal, using the wiring list, hookup drawings and foil pattern
reproductions of this and/or other manuals.
d) Trace the path backwards by means of the test wire or follow it forwards by
using a voltmeter.
Important: Keep your inner cool and -if somebody else is watching - maintain an
air of "situation under complete control".
3.11 Testing of the Selector Switches Drawbars/Fixed
Stops
10
Advertisement
Table of Contents
