4-15. AUXILIARY POWER UNIT - Continued
4-15.3 Alternator - Continued
Connect ohmmeter between each stator
lead and stator frame. If reading is low,
Check rotor for grounds using ohmmeter
between each slip ring and the rotor shaft.
Reading should be very high, otherwise
Check rotor for resistance between slip
rings. Reading should be 2.4 - 3.5 ohms.
If not, replace rotor.
Clean slip rings with emery cloth (item 13,
Appendix E) while rotating rotor.
Check diode trio by connecting ohmmeter
between each short lead (A) and single
long lead (B).
Current should flow from short lead (A) to
long lead (B), but not in reverse. Check
all short leads. Replace diode trio if any
lead is faulty.
Check rectifier bridge with ohmmeter
connected from grounded heat sink (9) to
flat metal (10) on terminal. Reverse
leads. If both readings are the same,
replace the rectifier bridge.
Repeat test between grounded heat sink
(9) and the other two flat metal strips (10).