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HWT-500 MAINTENANCE AND REPAIR
The HWT-500 test set utilizes durable switches and components to insure years of maintenance free service.
If maintenance is required, the unit should be serviced in a clean environment away from and disconnected
from energized circuits. The following routine maintenance is recommended:
A. Remove the test set cover and examine the unit for signs of collected dirt or moisture.
B. Remove the dust covers on the P1 and P2 cable input sockets and examine the contacts for excessive
dust, moisture or corrosion.
C. Any collected dust should be removed with dry compressed air.
D. Any collected moisture should be absorbed, as much as possible, into a clean cloth or towel. The unit
can then be placed into a slightly elevated temperature environment (40 C) to force dry the remaining
moisture.
E. Inspect the two cable assemblies for loose connections to the alligator clips or for frayed wires.
The major active components of the HWT-500 test set are mounted to the front panel assembly or are located
within the body of the test set case.
To gain access into the case:
1. Remove the qty. (4) ¼-20 bolts located at the left and right hand side of the front panel.
2. Remove the qty. (4) ¼-28 bolts used to secure the VARIAC to the front panel assembly. These are
located outside the VARIAC circular dial plate.
3. Remove the VARIAC knob using a 3/32 Allen wrench. Note there are two set screws securing the knob
to the VARIAC shaft.
4. Using the black face mounted handles, carefully lift the panel assembly over the VARIAC shaft and tilt the
panel assembly on the left-hand side of the test set.
5. At this point, the front panel assembly can be separated from the case by removing P1 and P2, 28 pin
plugs. These plugs are fixed to their respective sockets with two hold-down screws.
NOTE – DO NOT tighten these hold-down screws beyond hand tight.
To re-assemble, reverse the above sequence. Make certain that the P1 and P2 plug are inserted into the
correct plug position. Again, do not over-tighten the plug hold-down screws beyond hand tight. Make certain
that none of the harness gets pinched between the front cover plate and the body of the test set.
A list of available renewal parts is tabulated in Table 2 on page 41.
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