Testing External Voltage Regulator

gjp1960 · 05-05-2004, 07:55 PM

I'd like to test the external voltage regulator on my 73.5, and was hoping someone could give me a description of the exact steps to follow. I am not very good with electricity, but I do have access to a voltmeter. I tried a couple of forum searches but couldn't find anything that shows right where to test and what readings I should look for.

Its got a Marchal alternator which checked out fine at a reputable shop. The regulator has "SEV Marchal" stamped on the front of it (oriented upside down) and from what I can tell has 5 wires hooked up to it - three right into the box itself and two to the mounting bracket.

Any help you could give would be greatly appreciated.

More background - the generator light came on full, all at once, while driving at highway speed a week ago. Belt was intact and tight. Batteries (new last year) showed 12.3v or so at rest, dipping slightly with engine running. I removed the alternator (shot in the dark) and had it tested. It checked out. Now I am ready to be more scientific in my approach.

Thanks! Greg

gjp1960 · 05-06-2004, 05:54 PM

Can anyone help with this?

pwd72s · 05-06-2004, 06:34 PM

Greg, if you can live without your car for a spell...sent your voltage regulator to this guy, Loren @
http://www.systemsc.com/
Your original style external regulator is NLA...there are modern replacements available from out host, but they don't look the same. If originality is your bag, you might try to buy used spares, have them also checked out. Try to rig a voltage gauge..either by wiring a cheap male 12V plug to a multitestor and plugging it into you cig lighter, or wiring in a voltage gauge...something the factory should have done. As you drive, observe the read-out...if 13.5-14.5 you should be okay...lower voltage at lower revs, higher voltage at higher revs.