HP 5501A Operating And Service Manual page 224

Table 6-1. HP-IS Interface Electronics System Troubleshooting (Cont'd)
DATA ERRORS (Cont'd)
SYMPTOM CAUSE ACTION
Error in displayed 1. Compensation 1. Check output of
reading
i s
less circuitry compensation cir-
than one part in malfunction cuitry.
100,000 and is evident
on all measurement
axes.
Laser system reads Misalignment of the 2. If Comp. number
a shorter distance optics resulting in correct, check
than the known cosine error. for cosine
movement of the error in optical
optics. alignment (Refer
to Section II, Laser
and Optics).
3. If Comp. number
incorrect, re-
place 10755. If
using 5510, check
BCD inputs to
10755 using logic
probe and verify
correct Comp.
number is being
input.
Error in displayed 1. 10760A Mal- 1. Troubleshoot
reading that is function. or replace 10760A
less than one
part in 100,000
and is evident on 2. Cosine error 2. Align optics
a single measure- in optical (Section 11)
ment axis. alignment
3. 107806 Saturation 3. Adjust 10780A
(Refer to
10780A Manual)
ERROR DETECTION
4. If an error indication does not occur when the laser beam is interrupted in a measurement axis:
a) Check LED indicator on associated 10780A receiver. If it extinguishes when beam
is
interrupted,
proceed to step
b.
If it remains on when beam is interrupted,
1. Monitor 10780A test point on back of receiver. If voltage is greater than 1.1V dc, refer to
10780A manual to reduce receiver gain.
2. If voltage
is
in limits, check for incorrect rotation of optics or receiver (refer to Section 11).
3. If problem continues, troubleshoot or replace 10780A receiver.
b) If error does not register on any measurement axis, check, replace or troubleshoot system
interface card (10745).
c) If error does not register on one measurement axis only, replace or troubleshoot the associated
10760A card.