AR 10044393, Operating And Service Manual, Page: 25 / 30

Rev A 9
4. MAINTENANCE
4.1 GENERAL MAINTENANCE INFORMATION
The Model 5U1000 should require very little maintenance since it is a relatively simple instrument. It is built
with etched circuit wiring and solid state devices which should 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 within Amplifier Research instruments are designed for maximum instrument reliability; however,
parts within an instrument may fail. To repair an instrument with a minimum of "down time", a systematic
approach can greatly simplify and speed up the repair.
Due to the importance of the amplifier's alignment, when failure is caused by breakdown of any of the
components in the signal circuits, the amplifier must 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 COVER AND CIRCUIT BOARD REMOVAL
CAUTION:
Remove power cord from receptacle before servicing.
1. To remove the amplifier from the housing, remove four screws from the front panel. The amplifier can
then be slid from the housing.
2. The top cover can be removed to gain access to the RF assembly. The bottom cover can be removed to
gain access to the power supply assembly.
4.3 TROUBLESHOOTING
CAUTION:
The RF transistor used in the 5U1000 amplifier are GaAs FET's. These
devices are very reliable when installed in a suitable circuit but can be easily
damaged with improper troubleshooting or handling techniques. The gate
junctions of the GaAs FET's have a high input impedance and are
susceptible to static damage or damage due to an ungrounded soldering
iron. Do not try to check FET's with an ohmmeter. Use caution when
troubleshooting; do not short the gate to ground or to the drains.
CAUTION:
Use care when unpacking new FET's. The FET packaging should only be
opened at static approved work stations, by individuals familiar with the
handling of static sensitive RF GaAs FET's.