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harman/kardon Incorporated, 80 Crossways Park West, Woodbury, New York 11797 (516) 496 3400

Service bulletin # 9601 - January 1996

Warranty labor rate: MINOR repair

To: All harman/kardon Service Centers

Models: AVR10 / AVR-20 / AVR-20II Surround receivers

Subject: Intermittent Mute in FM or No FM
_____________________________________________________________________________________

In the subject models, the Audio signals from the MPX decoder are muted under two conditions:
1) When signal strength is low
2) When the voltage output from the Center Tune Detect (CTD) circuit is not zero. The CTD circuit
prevents the Tuner from stopping on the side bands of FM stations while in the SEEK mode.
Adjustable Coil T803 determines the CTD frequency.

In the event you receive a unit from a consumer with a complaint “FM cuts out intermittently”, perform
the following steps:

1) Locate on the tuner PCB coil T803 and R809.

2) If the value of R809 is either 47 kOhm or 56 kOhm, solder a 56 kOhm resistor in parallel with R809.
    (By adding this resistor, the bandwidth of the CTD circuit is increased)

3) Check and align the Center Tune Detect frequency as shown in the alignment instructions below.

Center Tune

Tune to a strong FM station around
the center of the FM band (98.1MHz)

DC mV
meter across
R809

T803

Less than 50 mV DC