"There is no mention in the OM
"There is no mention in the OMC 1971 100hp service manual pertaining to the amplifiers output to the ignition coil, only what the amplifier should draw if it is functioning properly. The test must be performed in a specified manner as set down in the manual.
Remove amplifier purple lead from terminal #8. With a low reading ammeter connected between that purple lead and terminal #9. With key switch in the ON position, the draw should be minimum, no more than .2 amperes.
If engine runs, the current draw at 4500 rpm should be between 2.0 and 4.0 amperes.
If readings are higher or lower, the amplifier is to be replaced.
Another method (easier) to test the amplifier is as follows:
(Battery Capacitance Dischage Powerpack Test)
Various OMC Engines - 1968 to 1972)
(J. Reeves)
Purchase a small 12v bulb at your local automotive parts store (the 12v bulb is to look like a flashlight bulb, not a headlight bulb). Solder two wires to that bulb, one to the side of the bulb (ground), and the other to the positive point. You might use a bulb of a somewhat lower voltage to obtain a brighter glow... just a suggestion.
Remove the spark plugs. With the key in the on position, make sure that you have 12v going to the pack at the terminal block (purple wire). Now, connect the ground wire from the bulb to any powerhead ground. Connect the wire from the positive point of that bulb to the powerpack wire that is connected to the coil wire on the terminal board (blue wire).
Crank the engine and observe that bulb closely (CLOSELY!). If that bulb glows even the slightest bit, the powerpack is okay. It may be a very dim glow... just so it glows! If it doesn't glow, the pack has failed.
Keep in mind, that type powerpack (Battery Capacitance Discharge) demands a top notch battery of at least 70 amp hours. Any less will, in time, cause powerpack failure.
When time permits, visit my store (copy/paste) at:
http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
