24-00-00 Page 24-5 Revised: February 28, 2002
CHART 2401. TROUBLESHOOTING (ALTERNATOR)
Trouble Cause Remedy
Zero output indicated on ammeter regardless of RPM (refer to alternator system test procedure). Open field circuit. Open output circuit. With master switch turned on, check for battery voltage from airplane’s main bus through entire field circuit to alternator field terminal. Measure voltage from ground (-) to the following points (+) in sequence; bus bar, output circuit breaker (5A), field terminals of master switch, voltage regulator and alternator field terminal. Interruption of voltage through any of these points isolates the faulty components or wire which must be placed. (See wiring schematic.) With master switch turned on, check for battery voltage from airplane’s main bus through entire output circuit to alternator battery post. Measure voltage from ground (-) to the following points (+) in sequence: bus bar, output diodes, ammeter and alternator battery post. Interruption of voltage through any of these points isolates the faulty component or wire which must be replaced. (See wiring schematic.)
24-00-00 Page 24-6 Revised: February 28, 2002
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CHART 2401. TROUBLESHOOTING (ALTERNATOR)
Trouble Cause Remedy
Zero output indicated on ammeter regardless of RPM (refer to alternator system test procedure). (cont.) Open field winding in alternator Disconnect field terminal of alternator from field wiring and check for continuity from field terminal to ground with ohmmeter (20-100 ohms) depending on brush contact resistance. — WARNING — TURN MAGNETO SWITCH TO OFF BEFORE TURNING PROP. (Pull propeller slowly by hand turning alternator rotor through 360° of travel.) If resistance is high, check brushes for spring tension and excessive wear and replace if necessary. If brushes are okay and field reads open, replace alternator.
Output indicated on ammeter does not meet minimum values specified in alternator system test procedure. Faulty voltage regulator. Start engine, turn on load (ref. alternator test procedure), set throttle at 2300 RPM. Check voltage at bus bar (convenient check point, remove cigar lighter and check from center contact (+) to ground (-). Voltage should be 13.5 volts minimum. If voltage is below this value, replace regulator.
24-00-00 Page 24-7 Revised: February 28, 2002
CHART 2401. TROUBLESHOOTING (ALTERNATOR)
Trouble Cause Remedy
Output indicated on ammeter High resistance connections Check visually for loose
does not meet minimum in field or output circuit. binding posts at the various
values specified in alternator junction points in system,
system test procedure. (cont.) Open rectifier. alternator battery post, lugs on ammeter, connections at voltage regulator, circuit breaker, etc., (See wiring schematic.) Examine crimped terminal ends for signs of deterioration at crimp or strands of broken wire at crimp. Tighten any loose binding posts or replace bad wire terminals. If any of the six rectifiers pressed into the rear bell housing of the alternator open up internally, it will result i a definite limitation on the current that can be drawn from the alternator. After having checked the previous causes of low output it can be assumed that a faulty rectifier exists.
Field circuit breaker trips. Short circuit in field circuit. Disconnect field wiring at terminal of alternator. Turn on master switch. If breaker continues to trip, proceed to disconnect each leg of field circuit, working from the alternator towards the circuit breaker until breaker can be reset and will hold. Replace component or wire which was isolated as defective. (See wiring schematic.)
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