Indication Of Protection Information - Yamaha A-S701 Service Manual

• Indication of protection information

The protection information is indicated by the flashing pattern of the "z"(power) indicator.
Types of protection function /
Flashing 2 /
PS protection /
Flashing 3 /
I protection L/R ch /
Flashing 4 /
DC protection /
Flashing 5 /
USB OC protection /
(U,R,A,B,G,L models)
Flashing 6 /
THM protection L/R ch /
Flashing 7 /
Diode THM protection /
Lit up/
No protection function /
PS (Power Supply) protection
Cause: The voltage in the power supply section is abnormal.
Normal value: 2.559 to 3.259V (AD value: 130-167)
Detection port: PRV (FUNCTION (1) P.C.B. 93 pin of the microprocessor IC502)
ACL, ± 15, +5S
Detected at:
I protection L/Rch
Cause: Excess current flow into amplifier.
Speaker terminal shorted. (*)
Normal value: LOW (0V)
Detection port: PRI (FUNCTION (1) P.C.B. 69 pin of the microprocessor IC502)
Detected at: PRI (Amplifier output L/Rch of MAIN (1) P.C.B.)
* If the protection function works due to shortage at the speaker terminal, the power turns off at the excess current
protection L/Rch.
However, pressing the "z" (power) switch for OFF/ON, all "INPUT" indicators flash 5 times and the power to turn on.
DC voltage protection
Cause: Abnormal DC voltage of amplifier output.
Normal value: 0.947 to 2.517V (AD value: 48-129)
Detection port: PRD (FUNCTION (1) P.C.B. 89 pin of the microprocessor IC502)
Detected at: Amplifier output L/Rch of MAIN (1) P.C.B.
USB OC (Over Current) protection
Cause: USB power supply is overcurrent.
Normal value: HIGH (5V)
Detection port: USB_N_OCPRT （FUNCTION (1) P.C.B. 45 pin of the microprocessor IC502）
Detected at: USB_OCPRT (IC309 of DIGITAL P.C.B.)
THM protection L/Rch
Cause: Abnormal temperature of heat sink.
Normal value: A-S501: 0.20 to 1.80V (AD value: 10-91)
A-S301: 0.20 to 1.66V (AD value: 10-85)
Detection port: THM1 (FUNCTION (1) P.C.B. 84 pin of the microprocessor IC502)
THM2 (FUNCTION (1) P.C.B. 83 pin of the microprocessor IC502)
Detected at: THML (Heat sink temperature detection Lch IC101 of the MAIN (4) P.C.B.)
THMR (Heat sink temperature detection Rch IC102 of the MAIN (5) P.C.B.)
Power indicator flashing pattern
500mS 500mS 500mS 1000mS
500mS 500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
Fig. 6
500mS 500mS 500mS 1000mS
1000mS 500mS 500mS 500mS
500mS 500mS 1000mS 500mS
500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
500mS 500mS 500mS 500mS 500mS
Continuous
A-S701
: Lit
: Off
500mS
500mS
500mS
1000mS
500mS 1000mS
500mS 500mS 500mS 1000mS
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