AR 10045879, Operating And Service Manual

Page: 45 / 54

Rev A 27
4. MAINTENANCE
4.1 GENERAL MAINTENANCE INFORMATION
The Model 250U1000 requires very little maintenance since it is a relatively simple instrument. It is built
with etched circuit wiring and solid state devices that will ensure long, trouble free life. However, should
trouble occur special care must be taken in servicing to avoid damage to the devices or the etched circuit
board.
Since the components are soldered in place, substitution of components should not be resorted to unless there
is some indication that they are faulty. In addition, take care when troubleshooting, not to short voltages
across the amplifier. Small bias changes may ruin the amplifier due to excessive dissipation or transients.
Components in AR instruments are conservatively operated to provide maximum instrument reliability.
Despite this, parts within an instrument may fail. Usually, the instrument must be immediately repaired with
a minimum of down time. A systematic approach can greatly simplify and, thereby, speed up the repair.
However, due to the importance of the amplifier's alignment, it is recommended that when failure is caused by
breakdown of any of the components in the signal circuits, the amplifier be returned to the factory for part
replacement and amplifier realignment. Shipping instructions are as follows.
To return an item, contact AR Customer Service for an RMA number and shipping instructions. Returns from
outside the United States are not permitted without prior authorization. If shipping from outside of the United
States, closely follow all directions on the RMA form for return shipping and marking. See warranty
statement at rear of manual.
4.2 DISASSEMBLY PROCEDURE
CAUTION:
Extreme caution should be exercised when troubleshooting this unit,
particularly when measuring voltages in the power supply section of the
unit. Hazardous voltages do exist in the unit that could cause serious
injury to any personnel performing the measurements.
The amplifier can be removed from the housing by removing four screws from the front panel and four
screws from the rear securing brackets. The amplifier can then be slid from the housing. The top side and
bottom covers can be removed to gain access to the RF assemblies, power supply and control system.