HP 5501A Operating And Service Manual page 237

Table 6-3. Binary Controlled Comparator-Based System Troubleshooting (Cont'd)
DATA
ERRORS (Cont'd)
SYMPTOM CAUSE ACTION
Small measurement 1. 10762A Mal- 1. Substitute
errors occurring on function 10762A from
one positioning axis another axis.
2. Optical misalign- 2. Check for co-
ment sine error
(Refer to
Section 11).
3. Receiver 3. See 10780A
Saturation Manual for
adjustment
Error in displayed 1. Compensation 1. Refer to
reading, error i s circuitry "action" for
less than one part DAC errors.
in 100,000, and is 2. Software error
evident on all axes 2. Check soft-
3. Optical ware.
misalignment
Incorrect laser Controller reading 1. Write routine
position feedback status bits a s data in software
when system is at for null
null. (Position detection.
data is incorrect by
a large amount.) 2. If position
must be read
at null, clear
error bits
through soft-
ware and then
sample.
Laser System reads Optical misalignment
Refer to Section II
a shorter distance resulting in cosine for alignment
than the known dis- error procedure.
placement of the
optics.
4. If an error does not occur when the laser beam is interrupted in a measurement axis:
a) Check
LED
indicator on associated 10780A Receiver. If it extinguisheswhen 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 (10746A).
C) If error does not register on one measurement axis only, replace or troubleshoot the associated
107468 fast pulse converter and/or 1076214 comparator.
d)
Check user software for correct error checking routine (refer to Section IV).