Observe proper polarity of the rectifier output terminal when installing the replacement rectifier.
Install and tighten the rectifier retaining hardware.
VARIDRIVE ASSEMBLY (fig 2-10)
a. Description. The varidrive assembly provides an adjustable speed motive force for driving external components
that are tested on the test stand. A tachometer generator provides an output voltage that is proportional to speed to drive
the front panel TACHOMETER RPM meter. Repair at the direct support maintenance level is limited to removal and
replacement of a defective tachometer generator and varidrive assembly. This procedure can be done with the varidrive
assembly installed in the test stand. Procedures for the removal of the varidrive assembly from the test stand are
provided in paragraph 2-19.
b. Removal and Replacement of Tachometer Generator.
Disconnect main power from the test stand.
Remove eight 1/4-20 screws and lockwashers from both the upper and lower rear panels of the test stand,
and remove the upper and lower rear panels.
Disconnect the two-conductor cable from the terminal block on the load bank assembly.
Remove the retaining hardware that attaches the tachometer generator and bracket to the varidrive, and
remove the tachometer generator together with the bracket and coupling from the test stand.
Remove the coupling from the shaft of the tachometer generator. Remove the retaining hardware that
attaches the bracket to the tachometer generator, and separate the tachometer generator from the bracket.
Reverse the procedures of steps (1) through (5) to install the replacement tachometer generator.
DRIVE BRACKET ASSEMBLY (fig 2-11)
a. Description. The bracket assembly provides means for mounting and coupling to the varidrive of external
components that are to be tested by the test stand. Repair of the bracket assembly is limited to the removal and
replacement of defective mounting studs and a defective pivot arm. Procedures for removal of the bracket assembly
from the test stand are provided in paragraph 2-20.
b. Removal and Replacement of Hex Mounting Stud.
Change 1 3-28