McIntosh MR 71 - McIntosh MR 71 Front Panel Overview; Tuning Dial Scales Description; MR 71 Front Panel Indicators; Front Panel Volume Control

DECODER ALIGNMENT
ADJUST
TEST
LIMITS
On the top of the chassis is an opening labeled "MPX Light Adjust."
Insert a screw driver into this opening and turn the control completely
counterclockwise.
1 9KC phase coil
Adjust for
and 19KC
maximum DC
transformer (T7)
voltage
Adjust "MPX Light Adjuster” control completely clockwise.
38KC
transformer
bottom core
38KC
transformer
top core
Adjust for
maximum
voltage
Adjust for
stable scope
display
1. Turn off 19KC pilot on MPX generator.
2. Adjust top core of 38KC transformer to obtain a stable and uniform
1 KC signal scope display. This adjustment may be critical, so turn
core very slowly.
3. Turn 19KC pilot back on.
1 9KC phase coil 30db separation Modulate left channel and measure right channel output. Adjust 19KC
or more phase coil for minimum right channel output (maximum separation).
Remove all test leads from TP #2 for separation checks.
SAME
Modulate right channel and measure left channel output. Separation in
steps 5 and 6 should be at least 30db.
MPX light adj.
control—R3
This step checks the rejection of 19KC and 38KC frequencies. Residual output should be
at least 40db below modulated output.
Turn control until light comes on. Then back off just enough to cause the
light to go off. Then back off about 14 of a turn more. Light should
operate ONLY on an MPX signal.
5