(Battery Capacitance Discharge)
(Amplifier Ampere Draw)
(J. Reeves)
There is no mention in the OMC service manuals pertaining to the Battery Capacitance Discharge amplifiers ampere output to the ignition coil. From what I've read, it is stated only what the amplifier should draw in amperes if it is functioning properly. The test must be performed in a specified manner as set down in the manual, as follows.
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.
********************
(Voltage Drop To Battery Capacitance Discharge)
( Pulsepack When Electric Starter Is Engaged)
(J. Reeves)
On the older Battery Capacitance Discharge ignition systems (1968-1972), the electric starter reaches a point, even with a top notch battery, whereas the starter will draw excess voltage/current/whatever which results in a voltage drop to the pulsepack. The cure is to purchase a diode which is capable of handling 12 volts and installing it between the starter terminal of the starter solenoid (NOT the battery cable terminal) and the wiring terminal that supplies voltage to the pulsepack.
The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa. When that diode is installed in this manner, when the key is turned to the start position, the voltage that is applied to the starter is also applied directly to the pulsepack via the diode effectively eliminating the voltage drop and energizing the pulsepack with the required voltage needed for its proper operation.
********************
(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.
Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:
http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
********************
(Battery Capacitance Discharge Coils - Continunity Test)
(Joe Reeves)
Remove the primary wire the screw type terminal. Remove the coil and unscrew the HT wire from the distributor cap.
Connect the black lead of a ohm meter to the HT wire, then with the red ohm meter lead, touch the ground wire of the coil.
Then touch (still with the red lead) the wire that normally attaches to the powerpack output lead. You should get a reading on both touches (contacts). If not, check the HT wire by unscrewing it from the coil. After removing the wire, the check can be repeated using the internal threaded prong within the coil instead of the HT wire. Poor or no continuity of a coil is one reason for erratic or no ignition and/or s/plug fouling.
********************
(Battery Capacitance Discharge Ignition)
(Miscellaneous sensor and coil spark test.)
(Joe Reeves)
Also a test you can do to check the firing sensor and coil when all else seems okay.Remove the coil from its mounting temporarily, then unscrew the coil wire from the distributor cap. Now bolt the coil back up in its original mounting place. Position the brass screw end of that high tension coil lead 1/4" from a ground area of the powerhead.
Make sure that you have 12v going to the amplifier when the key is in the ON or START postition.
Disconnect the wire that leads from the amplifier to the firing sensor located under the distributor cap... usually a quick connect plug... but if it has to be cut and splices, so be it.
Tap the bare wire on the powerhead somewhere to create a grounding tap, simulating the metal rotor passing by the timing sensor (or a set or points opening/closing). This should make the coil fire and arc to ground!
You should also be able to make the coil fire simply by sliding a feeler gauge past the center portion of the timing sensor.
********************
