Onwa KR-1338, Service Manual

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Qverload on +5 V and + 32 V line is detected by U6. Overload on +12 V(MOTOR+)
line is detected by U7. When the +5 V and + 32 V line is reduced by a heavy load,
U6 or U7 becomes condctive and consequently disables the PWM controller thro-
ugh Q6, Q7 and Q8. Overcurrent on the main input line is detected by R13, R14
and R15. The voltage drop across Q6, Q7 and Q8 bec- omes large when the inve-
rter is overload. Overcurrent detector U3 disables PWM inverter U2 when the
voltage drop exceeds a certain level.
Overvoltage of mains input is detected by the U1. When the input voltage exceeds
41.6 V, the U1 becomes active and disables PWM controller U2
Scanner motor power (ANT+12V/ -12 V)
+12 V and -12 V (ANT +12 V/ANT -12 V) are used to drive 24 V scanner motor.
The power to the motor is turned on/off by the relay(K1) on the POWER SUPPLY
Board. The relay control signal from the SPU Board is supplied to Q52 and Q53
on the POWER SUPPLY Board. Pressing the TX key changes the ANT SW signal
state from 5 V to 0 V, and K1 is on to 12V.
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