Heathkit H9 - Page 42

Pase4o
@
CONDITION
POSSIBLE
CAUSE
5'1. No EIA output.
1. Jumper wires incorrectly installed.
2. Off Line
or
Break keys
pushed
in.
3. lc609A, lc609B, 1c604.
4.
Q601, Q602.
5.
D605 installed
backward.
52. NoTW
output.
1.
Jumper
wires incorrectly
wired.
2.
Off
Line
or Break key
pushed
in.
3.
rc609A,
tc609B, tc604.
4.
0601. 0602.
5. D605 installed
backward.
53. No TTL
output.
'1.
Jumper wires incorrectly installed.
2.
Off Line or Break key
pushed
in.
3. tc609A. tc609B.
No
parallel
input
or output
(general).
1.
Check all
handshakes:
6FV,
-
tc61gB, tc624t,tczo2.
OnV,
-
IC61OA,
1615D, Hold screen.
H6lTo
-
From
the external device.
m-M
-
rc61oB,
lc61sA, tc61sB,
tc618A, 1C619C, tC624B.
2.
Check
the
data
priority
latch
and encoder.
lC615B, 1C616,
1c611,
tc610D, tc6198, rC608B, rC608C,
tC608D.
3.
Check for defective
or
incorrec{ly
wired interconnect
cables.
55. No
parallel
input.
1.
2.
3.
Input buffer. 1C620, lC608C.
xBE' 1c707A. lc713A.
tc702.
56. No
parallel
output.
1.
Output latches. 1C621
,
1C622.
2. Load
parallel
signal from 1C702.
3. Check the handshakes
(see
item
54 above).
4. XBE' lC707A,
lC713A. XBE' is
generated
from the
UART
TBMT
(XBE
),
parallel
FDTI
lXae,;,
and reader
control.
Ail
three
signals must be high for
XBE'.
57. No handshake.
1.
Check
handshakes
(see
item
il
above).
58.
No echo
back on full
duplex.
1.
Computer not
set
for
echo back.
2. No
serial
input.
59.
Stays off line
or won't
go
off
line.
1.
2.
3.
4.
Off Line switch
on
the keyboard.
tc609B, lc609D.
Q603.
D602
delective
or
installed
backward.
60. Reader
start doesn't
work.
1. Install
a
jumper
from
the base to
ground
of
Q604
if there is no
external current loop.
2. D603 installed
backward.
3.
rc606,
tc707A,
tc713A.
4.
Q604.
61. Wrong
baud rates even if
the Terminal is
programmed
correctly.
1. 1c601,
1c602, tc607A, tc608A.
2. 4800/9600
baud
lines interchanged in harness
P601-2, P601-
3.
62. No
baud rate
output.
1.
Check
item
61 above.
rc607B,
tc607c.
2.