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Table 4- 2. Digital Circuits, Symptom Troubleshooting Chart (Continued)
SYITlptom
3. Screen blank.
4. No blanking between
character slots.
5. Charactersc'hange on
face of display after
being keyed in.
c.
Check Procedure
Connect an oscilloscope probe
to pin G of A 10 and repeat
check b.
a.
Check horiz and vert. drive
-
b.
c.
a.
pulses at A 14-22 and A 14-
24.
These maybe checked at
A2-K or A2-C.
Check minor sweep expansion
at A 14-43.
This may be
checked at A3-AB.
Check CR T protect circuits
(para 4-2. 7d).
Check blanking at video
amplifier A8 (para 4-2.
7~).
Corrective Action
If
the pulses are absent,
place Al O.
If
present,
replace A 9.
If
absent. replace A 14.
If
absent, replace A 14.
re-
Follow the procedure given
in para 4-2. 7d.
If
the blanking gates are
present, replace video amp-
lifier A8.
If
not present,
replace A 14.
Adjust the control on the
delay line for stability.
If
necessary, replace the
delay line read-write amp-
lifier A9 Or A 10 repeating
step 2.
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