Heathkit H9 Manual page 43

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MISCELLANEOUS PROBLEMS
CONDITION
POSSIBLE CAUSE
63. No erase to end of line.
1. Space generator on the keyboard (special character
generator). 1C404, 1C405, 1C406. A1 : 0, A2= 1 for a space.
2. Erase flip-flop is not being set. lC737D, lC723A.
3. A write is not turning on the space (A2) or enabling RAM WE.
lc737 A, lC737 C, lC7 17F, lC726A.
4.
RAM counter is not counting up on erase. lC722C, lC737B.
64. No erase page. 1. Check the items in condition 63 above.
2. Erase filp-flop is not being set by lC715A.
65. Erase continues forever (blank screen).
2.
Erase flip-flop lC723A is not being cleared.
1C730 or timing signals.
66. No scroll. 1. Scroll key not pushed in.
2. Cursor/scroll coincidence is not being clocked into lC709B.
rc733A, lC733B, lC705C, lC710B.
3.
+12 or +4 count up not being clocked into lC709A. lC735A,
tc735B. tC735D.
4.
Scroll logic. lC7158, 1C739, lC733C, lC733D, lC741A,
tc741B, tc742c.
67. No erase on scroll. 1. lC722A not sefting erase flip-flop.
2. Gheck the items in condition 64 above.
3.
1C724 (since the same pin ot 1C724 controls both the scroll
count up and the scroll erase, 1C724 is OK if either the scroll
count up or the scroll erase work).
68. The erased line, the erased block, or the cursor move to
the wrong position after a scroll operation.
1. No scroll count up. 1C506, 1C522.
2.
No count up scroll +4/scroll + 12 signal trom 1C724 (since the
same pin ot 1C724 controls both the scroll count up and the
scroll erase, 1C724 is OK if eitherthescrollcount
up orthescroll
erase work).
3.
The 47 O resistor between plug G pin 5 and plug C pin 5 on the
chassis is missing.
69. Scrolls regardless of the position ol the Scroll key. 1. Scroll key.
2.
Scroll logic (see condition 66 above).
70. No short form.
1. Short Form key.
2. Counter controls. 1C724, lC73O.
3. Counter multiplexers on the RAM and counter circuit board:
lC514A, lC514D (+2O + +121.
lC530A, lC530D (+'12+ +4).
4.
Check +20 counter. 1C502, 1C509, lC510B, lC510C.
71 . No long form. 1. Short Form key.
2. Counter controls. 1C724,lC73O.
3. Counter multiplexers on the RAM and counter circuit board:
lC514B, lC514C (+lQ +
-4).
l C 51 1A , l C 5 11C (+ 4 + - '1 21.
4.
Check +20 counter. 1C502, 1C509, lC510B, lC510C.
No auto carry. 1.
Auto Carry key not pushed in.
2. Counter controls. 1C724,lC73O.
3. Counter not counting up:
No carry output trom +4 (long form) lC515B, lC530B.
No carry outpul from j-20 (short form) lC510C.
Counter multiplexers 1C514, lC511A, lC51 lC, lC530A,
lc530D, rc528D.