34
DJM-850-K
1
2
3
4
A
B
C
D
E
F
1
2
3
4
5.5 ABOUT POLYSWITCH
This unit monitors the voltages of the main power-supply ICs, using the voltage-monitoring circuit. As resettable fuses
(PolySwitches) are also used, some circuits cannot be monitored by the voltage-monitoring circuit when any resettable fuse is
activated.
The resettable fuse opens when excess current flows and will be restored to a conductive state after the cause of the
corresponding circuit error is removed. (Replacement of the resettable fuse is not required if the corresponding circuit error is
remedied.)
Power-supply line using a resettable fuse:
V
+15A
Power-supply line using a resettable fuse:
V
-15A
A circuit in the I
N
PUT Assy may be in failure if the voltages of the above-mentioned power in the I
N
PUT Assy are 0
V
, with
the UTILITY LED (STBY_LED) not flashing.
Possible causes:
Abnormal audio input
Item to be checked:
Check the peripheries of the ICs in the I
N
PUT Assy to which the above-mentioned power is supplied.
1
INPUT ASSY
Power-supply line using a resettable fuse:
V
+HP_U
N
REG
A circuit in the SEC/HP Assy may be in failure if the voltages of the above-mentioned power in the SEC/HP Assy are 0
V
, with
the UTILITY LED (STBY_LED) not flashing.
Possible causes:
Abnormal or no HP output
Item to be checked:
Check if there is any abnormality in the periphery of Q105 or Q106.
2
SEC/HP ASSY
1. Unplug the AC power cord.
2. Check for any error, such as short-circuiting or defective parts, in the circuits downstream from the resettable fuse.
3. Repair the detective part.
SEC/HP ASSY
I
N
PUT ASSY
V
+15A
V
-15A
V
-15A
V
+15A
TH1: PTGL05AS3R9K2B5
TH2: PTGL05AS3R9K2B5
P101: RXEF075P-T
C
N
2
C
N
4
8
01
Poly switch
Poly switch
Poly switch
SEC/HP ASSY
V
+HP_U
N
REG
Q105
Circuits using the resettable fuses
Diagnostic procedure when any resettable fuse is activated
