Zeiss humphrey HFA II-i series, Руководство по обслуживанию на месте

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PROPRIETARY and CONFIDENTIAL
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SERVICE
BULLETIN
Instrument:
Humphrey Field Analyzer II-i
Subject:
Correction of Focus Motor Errors
No.:
FA2i-014
Date:
10 Oct 02
Status: Informational Pages: 1
INTRODUCTION
Some HFA2i units may produce focus motor positioning errors on an infrequent basis. These errors will
normally appear on the system log and can cause test failure. The following troubleshooting techniques are
most often used to detect focus motor errors; the motor exerciser test, belt tension check, detector check,
belt pulley check, and mechanical focus calibration.
PROBLEM
Use of the above mentioned techniques may not identify the problem source.
SOLUTION
Two more possibilities of focus motors have been discovered. The first, is glue on the projection assembly
rails, and the other is excessive friction between the rails and the carriage assembly bushings.
Glue on the rails -
If a slight amount of adhesive sticks to the projection assembly guide rails, during the repair or assembly
process, it may not initially cause problems, nor be noticed. Over time, the clock oil used to lubricate the
rail/carriage assembly reacts with the adhesive and becomes sticky. The sticky oil and adhesive
combination increases the friction between the projection rails and the focus motor carriage assembly. This
combination can cause focus motor position errors. In a few cases, it has been found that the adhesive is
located on the bottom side of the rails. More often, it will be on the rail that is closet to the color wheel.
Typically it is found on the rail end closest to the patient.
One method to determine if the instrument has glue on the rails is to use a small mirror and place it so you
can examine the rail bottoms. Another method is to loosen or remove the belt and move the carriage
assembly by hand, feeling the resistance as the assembly moves on the rails. A change in resistance
during carriage movement can indicate an adhesive deposit. The adhesive will appear as a brown-rusty
colored patch. If you find a deposit on the rails, use acetone to dissolve the deposit and clean the rail.
Replace the clock oil used to lubricate the rail after cleaning.
Excessive friction between the carriage and the rails -
Assuming you have examined the rails for adhesive and did not find deposits, the next most likely cause of
the focus motor errors may be due to excessive friction between the rail and the internal bearings of the
carriage assembly. To test for excessive friction, remove the belt and move the carriage assembly by hand.
Ensure that the rails are well lubricated with clock oil. If an abnormal amount of force is required to move the
carriage assembly along the rails, and the amount of force is relatively uniform throughout the range of
travel, the friction between the rails may be due to misalignment, and could be the cause fo the focus motor
errors. Do not attempt to repair the projection assembly rails and carriage. Order and replace the entire
projection assembly.