Heathkit H9 - Page 40

Pase38
@
CONDITION
POSSIBLE CAUSE
29. Writes wrong
character
from keyboard
1. Shorts between the X and Y scan and address lines
of
the
keyboard
encoder. 1C402.
2. tc402, 1c403.
30. Cannot write from the keyboard.
1. No
output
enable
(OE).
lC608D, lC611D, lC6198, 1C616.
2. Keyboard
bus
harness
plug
P402 disconnected.
31. Control characters
do not blink in
plot
mode. 1. No
3.75
Hz. lC741D, 1C401.
2.
Control character video/decoder. lC201A, IC2O7B, lC210D,
tc219D.
CURSOR PROBLEMS
CONDITION
POSSIBLE CAUSE
32.
No
cursor. 1. Cursor coincidence
gate.
1C503,
1C508, 1C520.
2. TPU cursor
gates.
lC710C,
lC710D.
3. Character
generator
cursor chain.
lC2O2, IC?O1C, lC208A,
tc218B.
33. No
cursor
movement
when characters are written on the
screen.
1.
No
-:20
count up.
lC734B
(1C
if
DAV),
lC722B,lC729A
2.
+20
counter.
1C502.
3.
+20
count uo defeated. lC708D. 1C720. lC729A.
34. Cursor controls will not move
cursor.
1. 1c727.
2. No 1C
pulse.
1C728.
3.
Cursor
movement latches
on
the keyboard. 1C407, 1C408.
4. Q401.
35. Cursor
moves
continuouslv. 1. Cursor movement latches not
being
reset. 1C407, 1C408.
Make sure
TPU
cycle
13J.
resets
all
four latches. 1C407,
1c408.
z.
36. 960 cursors 1. lc710c.
2.
Character
generator
cursor chain.
lC201C, 1C202, lC208A,
lc218B.
37. Wrong cursor movements from cursor
controls.
1.
5701
plugged
in
backward.
2. Wires in
plug
5701 interchanged.
38. Wrong cursor movements from
ASCII
data.
'|
.
Special character
movement circuits. lC703A,
lC703B,
lc703D, tc707c, tc72o, tc740B, tc740c, tc740D,lc721c,
IC721D,lC708D.
39. Cursor
won't home.
1. Cursor home switch.
2.
Cursor
latch enable. 1C728.
3.
Cursor latches. 1C501. 1C518. 1C512.
4.
Select, select cursor, or select scroll
lines. lC706A, lC71 1D,
lc734A, lC504A, lcsosD, lC529B, lC529C,
rC51
1C,
tC524A,
tc524B,tc524c, tC504D, tC517c, tc517D, tc528A,
lc528B.
40.
Cursor
moves
on control characters
or
rubouts when the
Terminal is NOT in
the
plot
mode.
'1.
Control character detector.
lC617A.
2. Rubout
detector.
1C613.
3. CC+ R decoder.
lC703B, lC703C,
1C797, lC7O2.
4.
+20
count uD deteat.
lC708D. 1C720.
lC729A.