Automac Replacement

Aug 19, 2005
30
Catalina 30 Florida
Hi,
I searched the forum including the 101 basics about electrical topics, but I'm left with one question.
After a lightning strike into the mast antenna of my Catalina 30 (1985) fried/destroyed all electronics and the some, I'm back running. The old Weems&Plath Automac's part looking like a large transistor had exploded, as did several fuses and the AFS 70 filter. But it looks as if my alternator stills works!
Trying to make sense with the wiring, I made diagram 1 as it was (the white wire was "ripped" off from the automac (I think)).
Diagram 2 is as it is now. I took the Automac and AFS70 out, but I'm left with that white wire,
From my understanding this is the field wire, used to control the alternator output.
If I start the engine, the alternator output voltage is zero. If I then put +12 V on this white wire,
the engine RPM'ss goes down a bit and the voltage rises fast to 14 and higher
(I disconnected it immediately :) ) So I assume the ALT is still working?
What is the cheapest way to get it to work normally ?
I found the SPACREEK Automac manual and alternator file, but I might be to stupid to make sense of it. It seems I can rewire the old regulator "back" to "normal" ? Or can I use an external regulator, as I believe the Automac was something like that ? And if, something cheap like a car regulator or do I need to for some hundreds for these Balmar magical thingies ?
Any help is appreciated !
 

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May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
You should be able to replace with an internal regulator. Take it to an alternator shop
 
Aug 19, 2005
30
Catalina 30 Florida
Thank you Leslie, but I am a bit reluctant to get a probably decade old alternator to an alternator shop (not that I know of one in the next 100 miles) in the hope they have a regulator that will fit on this alt. I know I can get a complete replacement like a OEM-Leece-Neville-Marine-Alternator-51-Amp (on Amazon and Ebay ) that probably fits, but that would be another $230.
 

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Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
WAIT

If your alternator is still working, and it sounds like it is, all you need to do is find out where to connect the "excite" wire.

BECAUSE the AutoMac used the EXISTING INTERNAL REGULATOR, which you still seem to or most likely have.

I had an AutoMac until I replaced my OEM Motorola with a higher output alternator and external regulator.

You do NOT want to put an external regulator on that alternator. But it's a great little unit.

Because I did both changes at the same time, I am sorry I can't tell you where to "land" that excite wire. Somebody should be able to, unless you have the Alternator Doctor's Handbook, which used to be available on the internet for free. I have a downloaded copy, so if you can't find it, pm me and we'll see what we can do.
 
Aug 19, 2005
30
Catalina 30 Florida
Thank you Stu, and yes, I knew you exchanged your Automac etc and got one of these expensive Balmar regulators ;-).
I also have your 3 "cartoon like (your words)" diagrams. And I have the "12 V Doctor's Alternator Book" from SpaCreek, if that's what you mean. And you are right that it seems the alt is working and the internal regulator seems still to be attached.

I think I will disassemble the internal reg to see what might have been changed and try to change it back. Maybe I'll find a diagram of that reg.

Thank you all for your help.
 
Aug 19, 2005
30
Catalina 30 Florida
You should be able to replace with an internal regulator. Take it to an alternator shop
Leslie, getting tired to hunt for the problem, I followed your advice (partially) and bought a new alternator.
If I find the time to drive to a place with a good alternator shop, I have the old one fixed to have a spare.
Was amazed that the exact match for the MR2049K was still available :)