ALTERNATOR SYSTEM TEST

1. SYSTEMS VOLTAGE TESTS - HOW TO START!

To aid in troubleshooting an Alternator System or to check out a new installation, the following voltage measurements, monitored at application system locations, will define to the operator proper system performance prior to start-up. To insure reasonable results, the operator should use a voltmeter which is within calibration limits.

The schematics in figures 2 and 4 depict the location of voltmeter in the system to monitor the applicable voltage levels. The voltage readings indicated are for reference purposes, as actual values are dependent upon the level or storage state of your battery. By using the battery voltage (V-1) as the reference level. The remaining voltage measurements should be in the same relative relationship as those in the sample measurements shown in figures 2 and 4.

Use figure 4 for all 24 volt JASCO Alternator Systems with internal spike protection Regulator J12M24SP.

Use figure 2 for all 12 volt JASCO Alternator Systems with internal spike protection Regulator J12M20SP.

**** IF YOU HAVE AN OLDER MODEL REGULATOR CALL FOR DIFFERENT SCHEMATIC.

When performing the measurement tests listed on figures 2 & 4, the following conditions should exist: Engine stopped; Battery switch closed; Alternator/Field switch closed.

   2. ADDITIONAL CHECKS - IS ALTERNATOR DEFECTIVE?

Check  for a shorted suppressor or protector. If you have an old style external protector (SVP-3, SVP-4) in line, disconnect the protector and observe system function. Proper operation indicates a defective protector. On units with combined Regulator/Protector systems, simply disconnect the orange lead from the regulator and measure resistance between the orange and black leads. Resistance for 24 Volt systems should be not less than 1500 OHMS and 12 Volt systems should not read lower than 1200 OHMS.

    3.   ADDITIONAL CHECKS - IS ALTERNATOR DEFECTIVE?

Isolate the alternator and check for output. Turn the master switch of the aircraft to the "OFF" position. Disconnect the voltage Regulator. Also disconnect external protectors (SVP-3 or SVP-4) if still in use.

Caution:  Failure to disconnect the Voltage Regulator, Voltage Protector or the Voltage Controller (Regulator and Protector combined) will result in damage to these units. Failure to comply with these requirement voids warranty. Turn off all accessory equipment (All electrical loads). Connect a jumper wire from a battery voltage source directly to the field lead (Green wire) of the alternator. Be sure this connection makes a direct circuit to the alternator field terminal. You are now ready to operate the alternator in an un-regulated mode. Turn the master switch to the "ON" position and start the engine. Increase engine RPM to ensure the alternator shaft speed is over 3000 RPM.

Caution: System damage can result if the alternator is operated for over 45 seconds with the jumper wire connected in this troubleshooting test. Failure to comply with this requirement voids warranty.

Full current output rating of the alternator should occur, and 2 to 3 times the system voltage should occur. If not, then the alternator is defective. If full output is observed, the alternator is good and either the wiring or the regulator is probably defective. SKYTRONICS IS THE ONLY FAA AUTHORIZED REPAIR STATION FOR THE JASCO ALTERNATOR SYSTEMS. For further information please refer to the diagram below or the main menu for troubleshooting the JASCO series Alternator.

                                TROUBLE SHOOTER - JASCO 12 VOLT FIGURE 2

TROUBLE SHOOTER - JASCO 24 VOLT FIGURE 4