January 15, 1961
Bulletin No. SB-824
Ignition Systems
SUBJECT: Testing battery ignition coil #378231 using Stevens magneto analyzer;
75 H.P. V4A & V4AL-13 & 13C alternator engines.
Testing the battery ignition coil on alternator engines can be accomplished with the
Stevens magneto analyzer provided a special resistor is used in the secondary circuit
(tower) of the coil, figure 1. Because of the coil's high voltage output, this test
adaptor is necessary in order to obtain an accurate coil test as well as protect the
analyzer from possible damage which may result from repeatedly feeding high, unaltered,
secondary voltage back into the test instrument.
Since accurate tests are the only ones which reveal the true condition of coils, the
following procedure should be adhered to when using the Stevens magneto analyzer:
A. TESTING COIL ON THE ENGINE:
1. ALWAYS DISCONNECT THE RESISTOR WIRE FROM COIL TO INSURE AN ACCURATE COIL TEST.
2. Set analyzer's 'A-B' switch and adjust coil index in the conventional manner
as for magneto-type coils. (Switch setting: B; coil index No: 25.)
3. Insert test adaptor into secondary circuit (tower) of coil as illustrated in
figure 1.
4. Connect black primary wire from harness of analyzer ('A', figure 2) to the coil's
negative (-) terminal.
5. Connect red primary wire from harness of analyzer ('B', figure 2) to the coil's
positive (+) terminal.
6. Connect red secondary wire ('C', figure 2) to test adaptor's terminal.
7. Test coil in conventional manner.
(over)