Piper COMANCHE PA-24-180 Service Manual page 557

OHMMECr A short circuit in the stator windings is
However, if all other electrical checks are
normal and the generator fails to supply rated output, shorted stator windings are indicated.
c. Diode Checks - Each diode may be checked electrically for a shorted or open condition.
Any one of the methods outlined below may be used.
Ohmmeter Method: One method of checking diodes is to use an ordinary ohmmeter commonly
found in service stations. The lowest range scale on the ohmmeter should be used, and the ohm-
meter should have a I1i volt cell. To determine the cell voltage, turn the selector to the lowest
scale, and then connect the ohmmeter leads to a voltmeter. The voltmeter will indicate the cell
voltage.
BRUSH HOLDER
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PIPER COMANCHE SERVICE MANUAL
rectifying diodes.
b. Stator Checks - To check the stator
windings, remove all three stator lead attaching
nuts (Figure 9-18), and then separate the stator
assembly from the end frame. The fit between
stator frame and end frame is not tight, and the
two can be separated easily.
The stator windings may be checked
with a I 0-volt test lamp or an ohmmeter. If
the lamp lights, or if the meter reading is low
when connected from any stator lead to the
frame, the windings are grounded. If the lamp
fails to light, or if meter reading is high when
successively connected between each pair of
stator leads, the windings are open (Figure
9-19).
FIGURE 9.18. SLIP RING END FRAME
FIGURE 9-19. CHECKING STATOR
ELECTRICAL SYSTEM
ISSUED: 8/18/72
3 B11