1-17 (E)
HDCU-900 MM
1-10. Circuit Protective Elements
The positive characteristic thermistor (for power supply) functions as a circuit protective element on the
AT-141, DPR-163, RC-86, IF-789A/789P (HKCU-901), FC-83 (HKCU-903) and LC-41 (HKCU-904)
boards of the unit. The thermistor increases the internal resistance and limits the current flowing to the
circuits when an overcurrent flows or when the ambient temperature increases and the element reaches
the specified temperature. If the elements operates, turn off the main power and inspect the HDCU
internal circuit. After removing the cause of the equipment abnormality and the temperature of the
element decreases, turn on the power again and operate the unit correctly. It takes about 1 minute for the
elements to cool down after the main power is turned off.
Board
Ref. No.
Address
Protective circuit/equipment
AT-141
THP800
A9
Circuit inside the board
THP801
B8
THP802
B4
THP901
G9
Circuit inside the board
THP902
F9
THP903
K1
THP901
H9
Circuit inside the board
THP902
G9
THP903
G8
THP904
L8
THP905
L8
THP906
M8
THP907
M8
RC-86
THP1
B9
Circuit inside the board
THP2
B9
IF-789A/789P
THP701
A9
Circuit inside the board
(HKCU-901)
FC-83 (HKCU-903)
THP821
B8
Circuit inside the board
LC-41 (HKCU-904)
THP601
B8
Circuit inside the board
1-10. Circuit Protective Elements
DPR-163
(Board suffix: -11 through -14)
DPR-163
(Board suffix: -22 and later)
