Sony BVU-950 - Page 14

DEFECT ANALISIS IN MICROCOMPUTERS
KY Microcomputer
- Hardware Check Mode
By shorting TP4 on the KY-101 board with ground,
the KY microcomputer enters the hardware check
mode in which the following operations are performed.
This mode makes it possible to confirm that all the
data sent from the KY microcomputer to the 7-
segment LED are correct,
While the KY microcomputer is operating, the
hardware check mode is entered when PO-1 (TP4) is
set to a low logic level.
(1) “8” lights for each of the digits of the 7-segment
LED (for 2 sec.).
(2) “8” lights for the lowest order 7-segment LED
digit, and at 0.5 second intervals the digits light
in high-order sequence (this is conducted twice
for the 8 digits).
(3) All digits from “0” to “°F” for the 7-segment
LED light at 1 second intervals.
(4) All 35 key lamps tight (for 4 seconds).
(5) Upon completion of steps (1) through (4), the
operation of the switches is checked. While
depressed, the switch matrix number is indicated
on the 7-segment LED. When a multiple number
of switches are set ON, display priority is given
to the lowest matrix number. When a switch is
not pressed, appears.
(6) During PO-1 is low, the status in (5) is maintained :
when it is high. the normal operation mode is
entered.
Key Switch Matrix
KEY SWITCH MATRIX
Display
(1) 88:88:88:88
(2)
(3)
FE:EE:EF:
FF -FP FP:
(4) All key LEDs
(5) .
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Light up for 4sec.
KEY SW CHECK MODE
1 | 6
as
2 1
VIDEO | ASSEMBLE | PREVIEW AUTO
AUDIO |
| sot
CH-1
REVIEW CUT
REW EJECT SEARCH EDIT REC
em STANDBY | AUDIO
CH-2
RECORDER | PLAYER | PB
i STOP |__ PLAY
| DATA
a:
||
1
TRIMG) | TRIM(-) | ENTRY
LED DISPLAY
GD ()
co
|
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x
3-2