Indication Of Protection Information - Yamaha KMA-1080 Service Manual

KMA-1080/KMA-980
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INDICATION OF PROTECTION INFORMATION

If any of indicators shown below fl ashes after turning on the power to this unit, it means that the protection func-
tion is at work and normal operation is not available.
● Details of Protection Information
a. DC protection
Cause: Abnormal DC voltage of amplifi er output L/R
Normal value: 0.312 to 2.327 V
Detection port: PRD (58 pin of microprocessor IC15)
Detected at: Amplifi er output L/Rch of MAIN P.C.B.
b. I protection
Cause: Excess current fl ow into amplifi er
Normal value: Low (0 V)
Detection port: PRI (56 pin of microprocessor IC15)
Detected at: Amplifi er output L/Rch of MAIN P.C.B.
c. TH protection
Cause 1: Abnormal temperature of heatsink.
Normal value: 0.3 to 1.5 V
Detection port: TH_R (57 pin of microprocessor IC15)
Detected at: Heatsink temperature detection IC401 of MAIN P.C.B.
Cause 2: Abnormal temperature of power transformer.
Normal value: 0.3 to 1.4 V
Detection port: TH_R2 (54 pin of microprocessor IC15)
Detected at: Power transformer temperature detection IC402 of MAIN P.C.B.
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MUSIC indicator flashing: DC protection
KEY CONTROL indicator flashing in red/green alternately
MIC indicator flashing: TH protection
ECHO indicator flashing: I protection