Troubleshooting For 7Seg Led Test Error; Troubleshooting For Switch Test Error - Sony HKDV-900 Maintenance Manual

2-3. Troubleshooting

2-3-8. Troubleshooting for 7SEG LED Test Error

The display does not appear properly
Is the harness between CN401 (A-3) on the
CP-364 and CN2 (A-1 : B side) on the
CP-365 boards properly connected?
OK
Is WR signal of control ICs (IC308 (F-2) and
IC310 (F-2) on the CP-364 board) proper?
OK
Is output signal (ON : +3 V to +4 V/OFF :
GND) of control ICs (1Q1 to 2Q3 of IC308,
and 2Q7 and 2Q8 of IC310 on the CP-364
board) proper?
OK
Is power supply (anode : +2 V) to LED
proper?

2-3-9. Troubleshooting for Switch Test Error

The LED does not light even if the button is pressed
Is input signal (ON : low/OFF : high) at
I0 to I7 of IC309 (G-3) and I0 to I15 of
IC311 (G-3) on the CP-364 board proper?
OK
Is LED test OK?
NG
LED defect in switch or soldering defect
2-18 (E)
NG
Connect harness connector properly and
recheck them
NG
Connection defect between IC200 (G-1),
IC308 and IC310 on the CP-364 board
NG
IC308 (F-2) and IC310 (F-2) defect on the
CP-364 board
NG
Defect of resistor block (on CP-365 board)
NG
IC309 or IC311 defect on the CP-364 board
or soldering defect
HKDV-900