Heathkit H9 Manual page 42

P a se 4 o
@
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.