PLATE 7T7214 - Caterpillar

The 2P2340 Magneto Test Bench is used to make the tests of all of the magneto systems. Before making any tests, visually inspect the magneto for parts that have damage. Always make sure the drive coupling on the magneto is free to turn a minimum of 3 revolutions. A multimeter with the ability to give accuracy with an input of 30,000 ohms per volt or more is also used in these tests.Some of the time, a magneto will operate correctly at room temperature but will have a failure when the magneto becomes hot. An oven with the ability to heat a magneto evenly to 190° to 200° F, is used for this test procedure. Always do this test before putting the magneto back in service.
When adjusting the timing of the magneto on the test bench, always use a screw driver that has insulation on the handle. If a potentiometer has a short circuit, a voltage of 160 to 180 VDC will be on the adjustment screw.
To determine the source of the problem in a magneto a series of tests are made before making any repair or adjustments. These tests will give aid to the serviceman in making a quick analysis of the problem. Once the area with the defect is determined, follow the corresponding REPAIR PROCEDURE. Always complete this series of tests after making any repair or adjustments to the magneto. A. There Is A Mechanical Problem In The Drive System
Turn the drive coupling on the magneto at least three or four complete revolutions. If the drive coupling does not turn or will not turn smoothly, disassemble the magneto and check all components for cracks, breaks or missing pieces. Make the necessary repairs as shown in the section MECHANICAL DRIVE REPAIR and do the FAILURE ANALYSIS again to be sure the magneto does not have any other problem.B. One Cylinder Fires Too Often; 6 And 8 Cylinder Magnetos
1. With the magneto still installed in the test bench, remove screws (1) from cover (2). Move the cover to one side and check for any loose or broken wires or wires with worn or broken insulation. If any loose or broken wires or wires with worn or broken insulation are found, make the necessary repairs. Do the FAILURE ANALYSIS again to be sure the problem has been corrected. 2. Remove screws (3). Move the power board and heat sink assembly to one side and check the wires as in Step 1.3. Put the heat sink and the power board section into position and install screws (3). 4. Put the selector switch of a multimeter to the 10 VDC scale. Turn the speed control knob from OFF to a point where the magneto is running at 1200 rpm. Put the negative probe of the multimeter on terminal (C-11) (distribution board terminal with white/yellow wire). Put the positive probe on terminal (C-1) (distribution board terminal with white/green wire). The generator bias is good if the voltage is between 2.15 and 4.50 VDC.