Read Harman Kardon AVR 25 (serv.man3) Technical Bulletin online
harman/kardon
Service Bulletin
Service bulletin # 9501 - February 1995
Warranty labor rate: MAJOR repair
To: All harman/kardon Service Centers
Models:AVR-25/AVI-200 Surround receiver/amplifier
Subject: Low impedance protect circuit, intermittent shut down.
The power rating for the AVR-25 and AVI-200 is 75 Watts into 8 Ohms. The AVR-25 and AVI-200
protection circuits will not activate until the loudspeaker impedance drops below 4 Ohms. During
transients in certain CD program material, the instantaneous impedance of some loudspeakers with
impedance ratings of “8 Ohms” can drop well below 4 Ohms. As result, the low impedance protection
circuit will be activated.
protection circuits will not activate until the loudspeaker impedance drops below 4 Ohms. During
transients in certain CD program material, the instantaneous impedance of some loudspeakers with
impedance ratings of “8 Ohms” can drop well below 4 Ohms. As result, the low impedance protection
circuit will be activated.
In the event you receive from a consumer one of these products with the complaint “unit shuts down
intermittently” change the components indicated in the table below. After the change, confirm the idling
current by measuring the voltage between the emitters of the output transistors. The test points are
TP1/TP2 and TP3/TP4. The voltage reading should stabilize at 26 mV after the unit has been switched on
for at least 15 minutes.
If needed, adjust idling current potentiometers VR264L/VR264R until you read 26 mV.
intermittently” change the components indicated in the table below. After the change, confirm the idling
current by measuring the voltage between the emitters of the output transistors. The test points are
TP1/TP2 and TP3/TP4. The voltage reading should stabilize at 26 mV after the unit has been switched on
for at least 15 minutes.
If needed, adjust idling current potentiometers VR264L/VR264R until you read 26 mV.
Change
From
To
h/k part# 5613-3281(0)
Power Transistor Q262L/Q262R 2SC3182(O)
2SC3281(O)(
Use larger Mica insulator) or
2SC1386(A)
h/k part# HT113022A0
Power Transistor Q263L/Q263R 2SA1265(O)
2SA1302(O)
(Use larger Mica insulator) or
2SA3519(A)
h/k part# 3069222970
Resistor
R275L/275R
1.8kOhm
2.2 kOhm
1/8 W
h/k part# 3069222970
Resistor
R276L/R276R
1.5 kOhm
2.2 kOhm
1/8 W
h/k part# 3479310061
Capacitor
C259L/C259R
0.068mfd
10.0 mfd
16 V
(minus to emitter of Q264L/Q264R)
(Electrolytic)
harman/kardon Incorporated, 80 Crossways Park West, Woodbury, New York 11797 (516) 496 3400
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