HP 5501B Operating And Service Manual page 109

e. In cases of marginal signal strength, the following factors should be checked:
•
Laser assembly output power
•
Sampler assembly function
The laser assembly output power should be checked according to Laser Power Output Test,
paragraph 4-12.
The sampler assembly can be checked as follows:
1. Remove power from the HP5501B.
2. Remove A4.
3. Rest the test polarizer, HP Part Number 1000-0616 (supplied with the HP5501B),
against the exposed Reference Receiver exit port of the sampler. The test polarizer
will serve as a viewing screen in order to examine the laser beam which is normally
incident on the Reference Receiver photodiode. Apply power to the HP5501B.
Examine the laser beam cross section illuminating the polarizer. It should be circular
and centered within a few millimeters with respect to the exit port. Slight eclipsing is
normal. If any intensity variations are visible across the beam diameter they should
be straight, regularly spaced lines of high and low intensity, not spots or irregular
shapes. Rotate the polarizer 90 degrees and repeat the above observations. The
sampler can be removed and the internal beam splitters and polarizer's examined
for scratches dirt or cloudiness. Check the A3CR5 lens for scratches, dirt, or
cloudiness. Also, see Liquid Crystal Troubleshooting, step f.
HP5501B
Service
8-49