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15. 400Hz TONE SWITCH
This is used for calibration of the record input level of the tape deck. When the switch is
depressed, the built-in oscillator operates and a 580mV sine wave signal output will be fed to the
four TAPE MONITOR OUT jacks.
16.
SUGGESTIONS FOR TROUBLESHOOTING POWER AMPLIFIER
16.1 EXCESSIVE LINE CONSUMPTION
a. Check for shorted rectifiers H009 and H010; also check C008 and C009.
b. Check for shorted transistors H708 and H709. H001, H002, H003, H004, H005, H006, H007
and H008, or check H715. Check for bias transistor H714. Check L004 for short.
CAUTION: BECAUSE THE DRIVER AND OUTPUT STAGES ARE DIRECT COUPLED,
COMPONENTS MAY FAIL AS A DIRECT RESULT OF INITIAL COMPONENT
FAILURE. IF A SHORTED TRANSISTOR OR ZENER DIODE IS FOUND, OR
CONTROL OR BIAS DIODE, BE SURE TO CHECK THE REMAINING DRIVER
AND OUTPUT COMPONENTS FOR SHORT OR OPEN CIRCUIT BEFORE
REENERGIZING THE AMPLIFIER.
16.2 NO LINE CONSUMPTION OF ZERO BIAS
a. Check the line cord, fuse, transistors H715, H001, H002, H003, H004, H005, H006, H007
and H008, and bias transistor H714.
b. Check for open rectifiers H009 and H010 or open L004.
Digitized in Heiloo Netherland
5/30/2017
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