Sony HKDV-900 Maintenance Manual page 22

2-3. Troubleshooting
Several LEDs light and stay the state
(1) Debugging switch check
Is switch S100-1 (J-3) on the CP-364
board set to ON?
OK
Is pin 5 of IC100 (H-3) on the CP-364
board low level?
OK
Is reset signal (pin 88 : high level) of
CPU (IC100 on the CP-364 board) proper?
OK
Is clock signal (pin 79 : 24 MHz
rectangular wave) of CPU proper?
NG
Is crystal oscillator output (pin 3 of X100
(H-2) : 12.288 MHz rectangular wave)
proper?
OK
IC106 (H-2) defect on the CP-364 board
or soldering defect
LEDs light and go off, but several LEDs do not light
Refer to item 5 "LED Test" of
Section 2-2-4, "Test Procedure".
2-10 (E)
NG
Set switch S100-1 to ON and test it again
NG
Switch S100 defect or soldering defect
NG
Switch S500 (J-1) defect or soldering defect
OK
Does address signal (pins 37 and 38) of
CPU present to TP521 (G-1) and
TP520 (G-1)?
OK
Is interrupt signal (pins 93, 92, 91, and 90
of IC100 : all high level) proper?
OK
Check data bus and address bus
(Is not pattern shorted?)
NG
X100 defect or soldering defect
HKDV-900