HarmanKardon-AVR20II-avr-sb1维修电路原理图.pdf

harman/kardon Incorporated, 80 Crossways Park West, Woodbury, New York 11797 (516) 496 3400 harman/kardon Service Bulletin Service bulletin # 9601 - January 1996Warranty 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. AlignmentEquipment settingsConnectAdjustment point Adjust for Center TuneTune to a strong FM station around the center of the FM band (98.1MHz) DC mV meter across R809 T803Less than 50 mV DC RadioFans.CN 收音机爱 好者资料库 harman/kardon Service Bulletin Service bulletin # 9601 -January 1996Warranty labor rate: MINOR repair To: All harman/kardon Service Centers Models:AVR-20/AVR-20II Surround receiver/amplifier AVR-25/AVR-25II Subject: Poor or intermittent reception of FM _ In the event you receive a unit from a consumer with a complaint “FM cuts out intermittently” use the procedure listed below in addition to the procedure listed in the service manual for FM alignment. To supplement the manual, for FM center tuning alignment follow these procedures; AVR20/AVR20II AlignmentEquipment settings AdjustAdjust For QuadratureTune to a known strong FM station around center of the band (98.1MHz) T8030 VDC across R809, confirm by tuning to another strong station. Repeat step 1 in service manual for minimum distortion. Repeat both steps again for optimum sensitivity. *note: step #4 in AM IF states adjustment point VR802, should be VR801 step #2 in FM IF states adjustment point VR801, should be VR802 AVR25/AVR25II AlignmentEquipment settings AdjustAdjust For QuadratureTune to a known strong FM station around center of the band (98.1MHz) T9030 VDC across R914, confirm by tuning to another strong station. Repeat step 1 in service manual for minimum distortion. Repeat both steps again for optimum sensitivity. harman/kardon Incorporated, 80 Crossways Park West, Woodbury, New York 11797 (516) 496 3400 RadioFans.CN 收音机爱 好者资料库