(5) Connect the VOM to read continuity be-
(2) Clean all other parts with cleaning solvent
and dry thoroughly.
tween pins A and B.
(6) Slowly bring up shaft speed of the tester.
(3) Inspect base, rotor cap, electronics and
At 290 to 310 rpm Element No. 1 should trip causing
base assemblies for cracks, corrosion, or other
an open circuit to appear between pins A and B.
(7) After Element 1 has tripped, check with
(4) Check rotor and shaft for cracks, corro-
sion, or other damage.
the VOM for continuity between pins A and C.
(8) Proper tripping of Element No. 1 is indi-
(5) Check the bearing (8) for excessive wear.
cated by meeting the conditions of steps (4), (6) and
(6) Replace any worn or defective parts.
(9) Connect the VOM to read voltage on pin D
with respect to ground.
There are no repair procedures for the
(10) Slowly increase the tester shaft speed
electronics and base assemblies. If this
while monitoring the VOM. When Element No. 2
portion of the speed switch is malfunc-
trips, the reading will go from O volts to 24 volts.
tioning, replace both assemblies as a
Trip speed for Element No. 2 (50/60 Hz) is 590 to
610 RPM. Trip speed for Element No. 2 (400 Hz) is
825 to 850 RPM.
c. Test Equipment. The following test equip-
ment will be required to properly test the speed
(11) Continue increasing shaft speed while
monitoring pin H for voltage. It should be at 24 volts,
dropping to O volts when the third element trips.
Trip speed for Element No. 3 is 1200 to 1225 RPM.
tester with O. 187 tach takeoff fitting, capable of opera-
tion up to 1225 RPM.
(12) After Element No. 3 has tripped, connect
the VOM between pins F and J to check for continuity.
(2) 24 Vdc power supply.
Continuity should exist after Element No. 3has tripped.
(3) VOM suitable for measuring cotinuity
(13) Slowly decrease shaft speed while moni -
and 24 volts dc.
toring pin D with the VOM for voltage. There should
be 24 volts present, dropping to O volts when Element
(4) Mating connector and cable for MS3102R-
No. 2 resets. "Reset speed", for Element No. 2,
should be no more than 100 RPM below the trip speed
noted in Step (10).
diagram of pins to be used during test, and perform
(14) Continue decreasing shaft speed while
the following procedures.
measuring for continuity between pins A and C with
the VOM. Continuity should exist between these two
pins until Element No. 1 resets, then an open circuit
should extst. Reset speed for Element No. 1 should
be no more than 100 RPM below the trip speed noted
(2) Attach the connector and cable to J37 of
in step (6).
the speed switch.
(15) Decrease shaft speed to O RPM. Monitor
(3) Connect 24 volts dc to pins E, G and I with
pin H for voltage with the VOM. Element No. 3 should
the polarity indtcated in the test circuit.
still remain in the tripped condition, resulting in 0
volts on pin H, and continuity between pins F and J.
(4) Using the VOM test for the conditions
(16) Depress and release the reset switch, S1,
on the speed switch. Pin H should now read 24 volts
Element No. 1:
on the VOM.
Pins A & B . . . . . . . . . . . . .
Pins A & C . . . . . . . . . . . . .
e. Assembly. Assemble speed switch in re-
Element No. 2:
verse order of disassembly.
Pin D . . . . . . . . . . . . . . . . . .
0 volts dc to ground
Element No. 3:
f. Installation Refer to Operator and Organiza-
tional Maitenance Manual and install speed switch in
Pins F & J . . . . . . . . . . . . .
reverse order of removal.
Pin H . . . . . . . . . . . . . . . . . .
24 volts dc to ground