Sharp MZ-80B - Page 12

Position is correct
but characters
are
abnormal
Displayed
characters are
abnormal
• Keyboard Block
D7
I
DO
MI
Al
AD
-\
-----/
B7
I
BD
LHO
A4
081A
A3
I
PlO
AD
~
I
INT lED
Does not accept key entry.
No: Check IC 37, 38, 39, 42 and 43.
Check the common line
of IC22, IC41 and IC44
and around the I C22.
Check
A, - Ao and D, - Do of 1C45 and
IC42.
Key strobe
Key board
cancelling. signal
Decoder
Block Diagram around Keyborad
,Point
Is key strobe present?
Yes: Check keyboard, IC24 and around it.
No: Check IC25, IC27, IC28. IC29 and IC36.
-10 -
If they are normal, check IC24 and
around
it.