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DTC- 300ES
sEcTtoN 3
ADJUSTMENTS
3-1. MECHANICAL ADJUSTMENT
When replacing the drum, finely adjust the tape path (in l.b times normal speed
FWD mode).
3-1-1. Tapc Path Fine-Adjustment (x1.5 FWD Mode)
Adjustment
l.
Connect CH- I of an oscilloscope to pin
@ of an offset
jig and CH-Z to pin @ of the offset jig.
2. Connect a 3.3k-ohm resistor between pins 7 (GAIN 2)
and 6 (GAIN l) of IC52b.
3. Connect the offset jig as shown below.
L I N E S
4.
Turn on the power switch, insert alignment tape Ty-
725L, and put the set into the TEST mode.
5.
Press the AMS (>>l)
button.
6.
Remove the YEL and RED leads of the offset jig and
adjust guides Sl and Tl so that the shape of the RF
signal waveform on the oscilloscope is close to a square.
7.
Connect the YEL and RED leads of the offset jig, turn
the offset jig's volume control, and fix the RF signal
waveform to a half level. At that time, finely adjust
guides Sl and Tl again so that the shape of the wave-
form is close to a square.
8.
Turn the offset jig's volume control, slowly change the
RF signal waveform in the vertical direction, and check
that the waveform uniformly changes in the horizontal
direction.
9.
Remove the two leads (YEL and RED) of the jig from
cNTs1.
(l) Check that peak value (B) of the RF signal wave-
form is 60mV or more.
(2) Check that the undershoot level of the RF signal
waveform's flat portion is within l0%.
10. If the specification is not satisfied, repeat Steps 3
through 9.
11. Check that there is no gap between the tape and lower
flange in guides S2, T2, T3, and F. Check that no curl
*
occurs when the tape touches the lower flange. If there
is a gap or a curl occurs, adjust each guide according
to the adjustment on the next page.
- 8-
Adjustment Location :
Mechanical guides 51 and T1
Guide Sl
A 4,/5
x o
Guide T1
A' 4,/5 or less
B,/10 or less
t:î
)--r tn
,-__-,F--
B,/10 or less
The curl indicates the distortion which occurs on the
tape in the FWD mode. When light is shone on the tape,
the curl can be viewed more visually.
A T F
P R o g E ô q a r | ô q r n p ç
oFFSET JIG
\
i::::=::::-:-
SERVO BOARD
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