Details Of Protection Information; Starting In The Protection Cancel Mode - Yamaha AS2000BL Service Manual

G Details of Protection Information
• PS (Power Supply) protection
Cause : The voltage in the power supply
section is abnormal.
Normal value : 0.804 to 1.604V
Detection port : PRV (FRONT P.C.B. 40 pin of
microprocessor IC502)
Detected at : CB21, CB22 and CB23 of power
transformer, +18V, +12C of
FUNCTION P.C.B., MC ±20V,
MM ±25V, LINE1 ±25V, LINE2
±25V, VOL1 ±12V and VOL2
±12V of FRONT P.C.B.
• PS AMP source protection 1/2
Cause : Abnormal voltage of amplifier
power source
Normal value : LOW (0V)
Detection port : PSVA1 (FRONT P.C.B. 48pin of
microprocessor IC502)
PSVA2 (FRONT P.C.B. 47 pin
of microprocessor IC502)
Detected at : PSVA1 (CB24 and CB26 of
power transformer)
PSVA2 (± B1, ±B2, ± B3 and
±B4 of MAIN P.C.B.)
• Amplifier DC voltage protection L/Rch
Cause : Abnormal DC voltage of ampli-
fier output L/R
Normal value : 0.332 to 1.028V
Detection port : PRDL (FRONT P.C.B. 3 pin of
microprocessor IC502)
PRDR (FRONT P.C.B. 2 pin of
microprocessor IC502)
Detected at : PRDL (Amplifier output Lch of
MAIN P.C.B.)
PRDR (Amplifier output Rch of
MAIN P.C.B.)
• Headphone DC voltage protection L/Rch
Cause : Abnormal DC voltage of head-
phone output L/R
Normal value : 0.229 to 0.635V
Detection port : HPPRDL (FRONT P.C.B. 62 pin
of microprocessor IC502)
HPPRDR (FRONT P.C.B. 63
pin of microprocessor IC502)
Detected at : PRDL (Headphone amplifier
output Lch of MAIN P.C.B.)
PRDR (Headphone amplifier
output Rch of MAIN P.C.B.)
• I protection L/Rch
Cause : Excess current flow into amplifier
Normal value : LOW (0V)
Detection port : PRIL (FRONT P.C.B. 21 pin of
microprocessor IC502)
PRIR (FRONT P.C.B. 20 pin of
microprocessor IC502)
Detected at : PRIL (Amplifier output Lch of
MAIN P.C.B.)
PRIR (Amplifier output Rch of
MAIN P.C.B.)
• TMP protection L/Rch
Cause : Abnormal temperature of heat
sink
Normal value : 0.200 to 1.550V
Detection port : THML (FRONT P.C.B. 1 pin of
microprocessor IC502)
THMR (FRONT P.C.B. 64 pin of
microprocessor IC502)
Detected at : PRDL (Heat sink temperature
detection Lch IC202 of MAIN
P.C.B.)
PRDR (Heat sink temperature
detection Rch IC202 of MAIN
P.C.B.)
G Starting in the Protection Cancel mode
CAUTION!
• If this product is used with a failure un-repaired and
the protection function disabled, the protection func-
tion does not work even in a dangerous state, possi-
bly resulting further in damage. Use special care
when using this mode.
• When the protection function works due to an I pro-
tection L/Rch, it is not possible to start this unit with
the protection function cancelled.
If the protection function works and causes hindrance
to trouble shoot, it will be possible to start this unit in
the protection cancel mode by following procedures.
• Operation procedures
Turn the "BALANCE" knob counterclockwise fully
and then while pressing down the "AUDIO MUTE"
switch, set the "POWER ON/OFF" switch to the
ON position. At this time, keep pressing down the
"AUDIO MUTE" switch for 3 seconds or longer.
The POWER indicator lights up and the power
supply relay (RY1 of FUNCTION P.C.B.) turns on.
POWER indicator
"POWER ON/OFF" switch "BALANCE" knob
A-S2000
"BALANCE" knob
"AUDIO MUTE" switch
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