JBL PSW 1200 (serv.man2) Service Manual / Technical Bulletin ▷ View online
Service Bulletin
Service bulletin JBL9701 - May 1997
Warranty labor rate: MINOR repair
To:
All JBL Service Centers
Models: PSW1000, PSW1200
Subject: Premature muting
At the moment the bass information at the audio input terminals exceeds 8 mV, these subwoofers switch from the stand-by
mode to the ON mode. Approximately 6 minutes after the bass information drops below the sensing threshold, the
subwoofer amplifier returns to the Stand By mode.
mode to the ON mode. Approximately 6 minutes after the bass information drops below the sensing threshold, the
subwoofer amplifier returns to the Stand By mode.
Some customers may experience a tendency for the PSW1000 or PSW1200 to “mute” or shut down when played at
a low level and negligible bass information is present. Actually, this is normal behavior for the subwoofer. If the unit
was designed to be extremely sensitive, it could sense small amounts of 60 Hz hum or noise picked up by the customer's
input cables, random RF noise, etc and the unit would never turn off.
a low level and negligible bass information is present. Actually, this is normal behavior for the subwoofer. If the unit
was designed to be extremely sensitive, it could sense small amounts of 60 Hz hum or noise picked up by the customer's
input cables, random RF noise, etc and the unit would never turn off.
In the event you receive a PSW1000 or PSW1200 with the complaint “unit is shutting off (muting) when low
levels of music are being played”, this complaint can be resolved by the removal of C78 from the PCB. See
drawing for location.
levels of music are being played”, this complaint can be resolved by the removal of C78 from the PCB. See
drawing for location.
By removing C78, the Standby to ON sensing threshold level is more sensitive to higher frequencies and will keep
the subwoofer ON with any program material. The subwoofer will still, of course, go into standby after 6 minutes of
receiving no input signal.
the subwoofer ON with any program material. The subwoofer will still, of course, go into standby after 6 minutes of
receiving no input signal.
JBL Incorporated 250 Crossways Park Dr. Woodbury, New York 11797 (516) 496-3400
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