90589 Rev B.3 4/13
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3.5 Filtering
The P702B power unit/amplifier can be supplied with a low-pass filter on special order.
The P702BF-1 is supplied with 20kHz low pass filter that gives a system response that meets MIL 740-2
when paired with a WR 742TF-1 or 726TF-1 accelerometer.
3.6 Precaution in use
The P702B should not be subjected to environments in excess of its specified temperature and humidity
ranges. It should be protected from condensation and corrosive atmospheres.
4.0 Maintenance and troubleshooting
The P702B power unit/amplifier is fully adjusted and ready to operate when received from Wilcoxon
Research. A new set of 9 volt alkaline batteries are mounted in the unit. Typically, the batteries have an
operational life of greater than 80 hours.
4.1 Battery replacement
Batteries need replacement when the battery condition indicator no longer glows as the ON/OFF/BATT
switch is depressed to the BATT position. Turn the P702B upside down, remove the four retaining
screws in the cover bottom and carefully slide the chassis out from the cover box. The batteries are
located inside supported on three sides by the PCB and resting on a foam pad. Simply unplug the snap-
on connectors and plug in the new batteries. Replace them in the cutout in the PCB, slide chassis back
in to cover box and replace the four retaining screws. Check the battery condition indicator to make sure
the new batteries function correctly.
4.2 Initial checks
Depress ON-OFF-BATT power switch to BATT position. The battery condition indicator should show a
steady green light. Release switch. Connect the proper cable to the TRANSDUCER input BNC on the
P702B and to the transducer to be powered. This cable should be free of kinks and cable connectors
should be clean. Connect a coaxial cable to the output BNC connector on the rear panel of the P702B
and to the readout or recording instrument. For the initial checks, a T-connector may be placed on the
TRANSDUCER BNC and the accelerometer cable connector to one side of the T-connector. The other
side is left open.
Set ON-OFF-BATT power switch to ON. The FAULT monitor light will glow red during the approximately
20 second warm-up time of the P702B. If this monitor continues to glow, the transducer and its cable
should be carefully checked to locate and correct the fault. If the monitor ceases to glow, indicating
correct operation, the open end of the T-connector should be shorted by connecting a short wire from
connector center to shell. The FAULT monitor should make the glowing stop. Disconnect the cable to
the transducer. The FAULT monitor should now glow again to indicate the presence of the open cable.
Reconnecting the cable should make the glowing stop. The system is now ready for operation. The T-
connector may be left in place or removed.
If the optional line a
daptor (LA704) is to be used, plug the adaptor’s output cable into the jack on the rear
panel of the P702B. Then plug the line cord of the adaptor into a source of 110 V 50/60 Hz power (or 220
