4-2
S MIC Chassis
4-2-2. Protection Circuit Operation Check
Input signal: Dot pattern signal
Controls: BRIGHT 8 Minimum
CONTR 8 Minimum
1. Connect (+) side of ammeter to pin 8 of CN503 on the
D board and (_) side to pin 8 of CN801 on the P board.
Note: Connect film capacitor of 0.1
uu
uu
uF/100 V in
parallel to the ammeter.
2. Adjust BRIGHT and CONTR controls of the front
panel so that the reading (IABL) on the ammeter
becomes the following specification.
Specification: IABL = 160 ± 30 uA
3. Apply 18.4 ±0.1 Vdc from the regulated DC power
supply to TP85 (or pin 6 of CN503) on the D board.
Adjust RV833 on the D board so that the protection
circuit works.
4. Apply 17.6 ±0.1 Vdc from the regulated DC power
supply to TP85 (or pin 6 of CN503) on the D board.
Specification: Protection circuit becomes inoperative.
5. Input the all white signal from the test signal generator.
6. Adjust BRIGHT and CONTR controls of the front
panel so that the reading (IABL) on the ammeter
becomes the following specification.
Specification: IABL = 520 ± 30 uA
7. Apply 17.7 ±0.1 Vdc from the regulated DC power
supply to TP85 (or pin 6 of CN503) on the D board.
Specification: Protection circuit becomes operative.
8. Apply 16.9 ±0.1 Vdc from the regulated DC power
supply to TP85 (or pin 6 of CN503) on the D board.
Specification: Protection circuit becomes inoperative.
9. After the completion of steps 2 to 9, be sure to apply
paint to RV833.
4-1-2. B
++
++
+ Voltage Check in DC Operation
Input signal: Dot pattern signal
Controls: BRIGHT 8 Minimum
CONTR 8 Minimum
1. Input 12 ±
0.4
Vdc from the regulated DC power supply
0
to DC 12V IN.
2. Connect the digital voltmeter to plus (+) terminal of
C1605 and ground on the D board.
3. Make sure that the voltage is within the following
specification.
Specification:
C1605 plus terminal (D board) = 40 ±0.1 Vdc or less
4. If the above voltage is out of specification, adjust
voltage with RV1601 on the D board. After adjusting,
be sure to apply paint to RV1601.
4-2. PROTECTION CIRCUIT (HOLD-
DOWN CIRCUIT) CHECK
4-2-1. Shutdown Voltage Adjustment
Input signal: Dot pattern signal
Controls: BRIGHT 8 Minimum
CONTR 8 Minimum
1. Turn RV1602 on the D board and stops where the
protection circuit doesn’t shut down.
2. Apply voltage of 9.4 ±
0.1
Vdc from the DC power
0
supply between pin 5 of L1602 and ground on the D
board.
3. Turn on the power.
4. Gradually turn RV1602 on the D board and stops
where the shutdown circuit works.
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