Read Sharp BD-HP21H (serv.man2) Service Manual online
BD-HP21U/S/H/A/X/RU/SB,BD-HP50U/X
2 – 17
A key fails to work.
Is the key switch contact and tightness as specified?
YES
YES
Check the line between each button and IC2504.
Or check the pull-up resistor at pin (63, 74 or 75) of IC2504.
(R2578, R2507, R2672)
Check the circuits that generate the control voltages.
Or check the pull-up resistor at pin (63, 74 or 75) of IC2504.
(R2578, R2507, R2672)
Check the circuits that generate the control voltages.
Is the control voltage properly applied at pin (74) (KEY_EJCT),
pin (75) (KEY_STBY), pin (63) (KEY_DOOR), pin (94)
(KEY_OPC1) or pin (95) (KEY_OPC2), all on IC2504?
* While the POWER, DOOR OPEN/CLOSE, TRAY OPEN/
pin (75) (KEY_STBY), pin (63) (KEY_DOOR), pin (94)
(KEY_OPC1) or pin (95) (KEY_OPC2), all on IC2504?
* While the POWER, DOOR OPEN/CLOSE, TRAY OPEN/
CLOSE or relevant button is held down, the "H" level
changes to "L" level.
Pins (63, 74 and 75) of IC2504
changes to "L" level.
Pins (63, 74 and 75) of IC2504
* PB, STOP, SKIP- and SKIP+ buttons
Press each of these buttons and make sure the voltages
shown in Fig. 1 are applied to the related pins of IC2504.
shown in Fig. 1 are applied to the related pins of IC2504.
NO
Check the relevant switch. Replace it as required.
NO
Check IC2504 and its peripheral circuits. Or replace IC2504
as required.
as required.
FLOW CHART No.6
Fig. 1
KEY_OPC1 KEY_OPC2
PLAY
SKIP+
SKIP-
STOP
0V
0.73V
1.76V
2.25V
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