Any Electrical / Alternator Experts?

[Chris Reinke]

Any Alternator / electrical supply experts?

My Motorola alternator failed during a recent cruise. A bench test confirmed that it had bit the big one after 11 years of faithful service. The only replacement which was available was a larger Delco "Marine One Wire" which the alternator shop spoke very highly about. I was able to mount the larger unit with the help of two shoe horns and a bit of Vaseline. The alternator has only one post on the rear plate which the alternator shop said would replace the existing 3 wire connection. They said that the functions which the other wires performed had been incorporated into the single wire and that I should just cap off the unused wires.

The alternator puts out like a champ (14.2v) and my electrical system has never operated better. My problem is those other two little wires. One of them (Grey) runs directly to my tachometer. The folks at Universal have indicated that this connection is used to determine engine RPM’s. They have indicated that a "AC TAP" needs to be added to the alternator. The local shop can add this tap for a minimal charge. I am hoping to avoid removal of the alternator and was wondering if any alternatives exist. The tachometer does not function currently.

My second problem is the pesty little purple wire. My Universal M-30 service manual wiring diagram shows the wire leading to the "A" post of the key switch. From this terminal it splits into three leads which:
1 - goes to the light terminal of the gauges (Tach, Temp, Amm)
2 - goes to the + post of the fuel pump
3 - goes to the + post of the tachometer and temperature gauge

My engine is fully operational and I believe the fuel pump is working, but can not say for certain. Any ideas of suggestions on what to do with this funny little wire? Does the power supply from the key switch to these other items need to come off the alternator?

I would not hope this problem on any of my fellow CD owners, but if anyone has any suggestions of comments I would be very grateful.



chris.reinke@transamerica.com

[Jefff Barnes]

Chris:

First, thank you for not wishing this problem on any of us. Cruising season, at least on the east coast is too short without having to deal with electrical problems.

With regard to your tachometer, you will ahve to have the tap added in order to revive the utility of your tachometer. Unfortunately, the beast will most lilely have to removed. This is actually a stator tap off the alternator, and assumikng the new delco has the same pulley size AND same number of poles as your deceased Motorola, should work OK tgiving a reasonable accuarte reading of engine RPM. Some tacometers are adjustable to account for different pulley sizes and alternator stators.

Regarding the the lonesome purple wire... This was most likely used to activate the alternator field and/or inyternal; regulaytor on your Motorola. the self excitaion characteristic of your new altetrnator obviates the need for this connection. It seems as long as items 1,2, and 3 that you refer to are activatted with 12 volts when the key is "on", you shoud be OK, and thus do not need to worry about the purple wire. The tachometer requires 12 volts (in addition to the grey wire) to operate, as does the temperature gauge.

Good luck and yell if you need more help.

Regards,

Jeff Barnes
"JAZMAN" CD36

[Murray Glue]

I have read the first response to your posting and concur with it.
The only alternative for your tachometer if you dont want to take it off
is to replace with a tacho with a generator source or one which
has an inductive transducer on the flywheel, if accessible. Both
probably more expensive than getting back in there and taking
it off again.



106452.2173@compuserve.com