HP 5501A Operating And Service Manual page 235

Table
6-3.
Binary Controlled Comparator-Based System Troubleshooting (Cont'd)
c) Check indicator LEDs on the 10762A Comparator card.
d) intermittent measurement signal on one or more measurement axes may indicate
CAUSE CHECK ACTION
1 . Misalignment of Reduce beam size by If optics are
optical components rotating to small misaligned and
aperature on laser beams do not
head. Place align- overlap, refer
ment target on
to Section II
receiver lens. Move for alignment
optics along entire procedure.
measurement path and
verify both return
beams overlap on the
target along the
entire length of
movement.
2. Misadjustment of Monitor 10780A test Refer to 10780A
10780A Receiver point on back of manual for adjust-
Gain receiver, voltage ment procedure.
should lie in range
0.5 - 1.OV dc. If
voltage >I.lV,
receiver could be
saturated. If volt-
age <.02V, gain may
be too low.
3. Low power in Use power meter, if Rotate interfero-
frequency used available, and meas- meter 90 degrees
for measurement ure relative power and look for in-
of horizontal and crease in test
vertical polarization.* point voltage.
4. 10780A mal- Look at output sig- Troubleshoot
function, cable nal from 10780 and appropriate
intermittent, or input of fast pulse component
107648 malfunction converter 107648.
'Use laser power meter filtered for 6328 Angstroms
(e.g., United Detector Technology MOX Meter (w/filter) ).