7035B Troubleshooting Index - HP -7035B Technical Manual

PROBLEM
1. One position of pen produces
excessive jitter that repeats
each time the pen reaches
this position.
2. Excessive pen jitter (small
amplitude).
3. Excessive Y-axis retrace
hysteresis (any slope).
4. Excessive X-axis retrace
hysteresis (any slope).
7-2
TABLE 7-1. 7035B TROUBLESHOOTING INDEX
POSSIBLE CAUSE
"Dirty" slidewire. High contact
resistance between slidewire
wiper and either resistance ele-
ment or pickoff strip.
a. Amplifier gain adjusted too high.
b. Strap between front panel guard
terminal and negative input
terminal disconnected.
c. Excessive common mode signal.
d. Excessive differential input
signal noise.
e. "Dirty" slidewire.
a. Amplifier gain too low.
b. Source impedance too high (1 mv/
inch, 0.4 mv/cm) range only.
c. Drive string too loose. Measure
tension per paragraph 5-66.
d. Pen carriage wheels set too tight.
e. Insufficient backlash in gears (too
tight).
f. Motor brushes excessively worn.
g. Pen speed too fast. Retrace
error should be small only at pen
speeds below 1 inch/sec.
h. Bearing in drive train faulty.
i. Faulty neon bulb in photochopper.
j. Excessive differential noise on
input signal.
k. Excessive friction.
a. Amplifier gain too low.
b. Source impedance too high (1 mv/
inch, 0.4 mv/cm) range only.
c. Drive belt too loose. Measure
per paragraph 5-78.
CURE
Clean slidewire (see paragraph 5-11).
a. Adjust (lower) gain per
paragraph 5-92.
b. Connect strap.
c. See Table 1-1.
d. See Table 1-1.
e. Clean slidewire (see paragraph 5-11).
a. Adjust gain (paragraph 5-92).
b. Lower source impedance
and/or increase amplifier
gain (paragraph 5-92).
c. Tighten drive string (paragraph 5-67).
d. Adjust pen carriage (per
paragraph 5-71).
e. Adjust backlash (paragraph 5-69).
f. Replace brushes (paragraph 5-38).
g. Decrease retrace pen speed.
h. Replace bearing.
i. Replace bulk (aging not required).
j. See Table 1-1.
k. Clean and lubricate per
paragraphs 5-9 and 5-13.
a. Adjust gain (paragraph 5-92).
b. Lower source impedance and/
or increase amplifier gain
(paragraph 5-92).
c. Tighten belt (paragraph 5-79).