Marantz PM-10 Service Manual

3. Protection operation
Explanation of UCOM (U1004) [PROT_1 : pin1, PROT_2 : pin2, PROT_4 : FATAL, pin31, PROT_5 : READY,
pin40, PROT_6 : M_B_DOWN, pin75]
[A] The PROT_1(pin1) is the port to detect the following abnormalities of
the Power Ampliers
(1) Detection of an abnormality in the DC offset voltage from the Speaker Output terminal.
If the voltage from the Speaker Output terminal exceeds approximately 2.2V (DC),[Q9001, Q9002,
Q9003, Q9004, Q9005, Q9019, Q9020 or Q9020] will turn on, then the signal from the "PROT_1" will
change to "Hi → Lo".
If "PROT_1" changes from "Hi → Lo" when the above abnormality is detected, the protection circuit
activates. "POW_1 : pin72" and "POW_2 : pin73" change from "Hi → Lo" and power relay [S8501-S8503]
immediately turns off and shuts down.
The STANDBY indicator ickers to inform that an error has occurred.
This protection operation is intended for when a failure occurs in the ampliers circuit and immediately
turns the power off to avoid the risk of any damage.
To check whether the amplier is broken, turn off the unit, then wait for about 1 minute and turn it on
again.
This action will deactivate the protection operation.
If the "PROT_1" remains in the "Lo" abnormal state, which constitutes an abnormality, the unit shuts
down approximately 8 seconds later and the STANDBY indicator starts ickering.
If the protection operation is not deactivated even after the power is turned on again, the ampliers
circuit may be broken.
[B] The PROT_2 (pin2) is the port to detect abnormalities of the power
supply circuit
(1) Detection of an abnormality in the pre-amplier power supply circuit.
This port monitors the midpoint voltage between +20V and -20V. If the voltage at the connection
point of [R8102, R8107] exceeds DC ± 1.2V, [Q8106 or Q8113] will turn on to change the signal
from the "PROT_2" to "Hi → Lo".
(2) Detection of an abnormality in the REC OUT/signal detection power circuit.
The middle point voltage between +18V and -18V in the REC OUT/signal detection power source is
monitored. If the voltage at connection point [R8108, R8111] or [R8135, R8136] exceeds around ±
1.2V (DC), [Q8107 or Q8114] is turned on and "PROT_2" changes from "Hi → Lo".
(3) Detection of an abnormality in the function relay power supply circuit.
If the +24V of the relay power supply receives an electric current of over 133mA, [Q8510, Q8511]
will turn on to change the signal from the "PROT_2" to "Hi → Lo".
(4) Detection of an abnormality in the electronic volume power circuit.
If undervoltage (2V or lower) or overvoltage (7V or higher) is detected in +5VA of the electronic
volume power supply, [Q8118 or Q8116] turns on to change "PROT_2" from "Hi → Lo".
When the abnormality mentioned in (1) or (4) is detected, "POW_1 : pin72" and "POW_2 : pin73"
change from "Hi → Lo" and power relay [S8501-S8503] immediately turns off and shuts down.
The STANDBY indicator ickers to inform that an error has occurred.
This protection operation is intended for when a breakdown of the power supply circuit occurs and im-
mediately shuts off the power in order to avoid the risk of damage.
To check whether the power supply circuit is broken, turn off the unit, then wait for about 1 minute and
turn it on again.
This action will deactivate the protection operation.
If the "PROT_2" remains in the "Lo" abnormal state, which constitutes an abnormality, the unit shuts
down approximately 5 seconds later and the STANDBY indicator starts ickering.
If the protection operation is not deactivated even after the power is turned on again, the power supply
circuit may be broken.
53
Caution in
servicing
Electrical Mechanical Repair Information Updating

Marantz PM-10 Specifications

General

Type	Integrated Amplifier
Frequency Response	5 Hz - 50 kHz
Total Harmonic Distortion	0.005%
Dimensions	440 x 168 x 453 mm
Weight	21.5 kg
Damping Factor	500
Available Colors	Silver, Black
Power Output	200W per channel (8Ω)
Input Sensitivity	220 mV / 22 kohm