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6. As shown in the equation below, read the FM
waveform value at point (b) and make sure that:
© 20.75 or 20 log 2-25 dB
. Read the values at points (c) and (d) [drum input and
output] and make sure that:
с
d
ua 0.75 and 3 2 0.75 or
20 log = = -2.5 dB and
20 log £ = -2.5 dB
NOTES:
. Read the minimum levels for (b), (c), and (d).
. If above checks yield normal results, proceed
to page MA-8 section "ADJUSTMENT".
. If defects are noted, perform the following FM
envelope waveform adjustment.
FM ENVELOPE WAVEFORM
ADJUSTMENT
. Asin Ше previous section, observe the FM waveform
and press the CHANNEL V / A buttons. Waveform
alterations must be nearly parallel to each other as
shown in Figure "Normal Waveform Examples" on
page MA-7.
. И the waveform changes as shown in the figure
below, adjustment is necessary.
Abnormal Waveform Example
5-2. ADJUSTMENT
MA-7
1.
Connect the TP of PB ENV to the oscilloscope
CH-1. Atthis time, trigger the oscilloscope externally
with the signal (RF Switching Pulse) from TP of RFS.
. Play the test tape (Stairstep).
DRUM INPUT ADJUSTMENT
. Observe the FM envelope output wave at the TP of
PB ENV with the oscilloscope and press the
CHANNEL V / A buttons in both positive (+) and
negative (—) directions.
. Aofthe following figure shows incorrect waveforms.
With a standard screwdriver, adjust the transport
guide roller to flatten the peak of the FM envelope
waveform as shown in B.
NOTES:
1. If the guide roller rotates freely, tighten the
screw slightly.
2. Be sure to adjust the guide roller only by small
increments at a time to avoid damaging the
test tape.
In addition to observing the waveform, make
sure that there is no slipping of the tape or
curling at the drum lead.
Y. Drum input
Supply Guide Roller Tape
[||
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Tight Screw
Supply Guide Roller
Drum Input Adjustment
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