Read Sharp ER-A850 (serv.man5) Service Manual online
2-2-4. Segment control
CKDC4 directly drives the 7-segment display unit.
7 segment drive time chart
The display tube employs a grid blanking dynamic drive and operates
in the following timing.
7 segment drive time chart
The display tube employs a grid blanking dynamic drive and operates
in the following timing.
<7-segment display>
2-2-5. Data test
Host ECR
→
CKDC4 in the ER-A8DP PWB
1) Host ECR
→
ER-A8DP (loopback test)
1
Set the data "A" in the shift register of the host ECR.
2
Send the data "A" to the ER-A8DP with shift clock added to the
host ECR and read the data on the ER-A8DP.
host ECR and read the data on the ER-A8DP.
3
Set the data "B" to the host ECR.
4
Send the data "B" to the ER-A8DP with shift clock’s added by the
host ECR. Then, sen the previous data "A" in the ER-A8DP to the
host ECR.
host ECR. Then, sen the previous data "A" in the ER-A8DP to the
host ECR.
The host cash register transfers data to ER-A8DP after eigth shift
clocks. In this event, the contents of the ER-A8DP shift register
(data A) is not destroyed.
clocks. In this event, the contents of the ER-A8DP shift register
(data A) is not destroyed.
5
The host ECR checks if the returned data "A" are properly trans-
mitted. The data "B" returns to the host ECR to be checked after a
next data or a dummy data are sent.
mitted. The data "B" returns to the host ECR to be checked after a
next data or a dummy data are sent.
2) CKDC4
→
host (repeated transmission of the same
data twice)
1
Set the data "A" in the CKDC4 side shift register.
2
Sent the data "A" on the shift clock and read it on the host side.
3
Set the dame data "A" in the CKDC4 side shift register.
4
Again, sent the data "A" on the shift clock.
5
On the host side, compare the data "A" read in
2
to check if the
transmission was achieved properly.
2-2-6. ER-35DP operation check
The SHEN signal is used to check lock up of the ER-A8DP. Normally,
it will complete within 2msec before SHEN is set after the host ECR
completed data transmission. If SHEN was not received within the
predetermined time, it will be error processed as an error.
it will complete within 2msec before SHEN is set after the host ECR
completed data transmission. If SHEN was not received within the
predetermined time, it will be error processed as an error.
OKDC4
+5V
G0-G6
SA-SG, DP, ID
-29V
7SEG-display
-29V
36.2µ S
44.8µ S
45.8µ S
58.2µ S
778µ S
778µ S x 11
Gm
DP, ID
SA, SB, SC, SD
SE, SF, SG, AP
Gm+1
Host ECR
Shift register
CKDC4
ER-A8DP
SCK
OUT
IN
OUT
IN
HTS
STH
SCK
ECR
A
ER-A8P
Unpredicatable
ECR
ER-A8DP
A
B
ECR
ER-A8DP
A
B
ECR
ER-A8DP
A
B
A
A
Unpredicatable
Host
CKDC4
A
Host
CKDC4
A
Host
CKDC4
Host
A
CKDC4
SHEN
SCK
30µ s ~ 2mms
4
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