MGB & GT Forum

Welcome! Sign In Register
Please Sign In or Register to Search

How to polarize positive ground generator ??

Posted by 67mgbrich 
67mgbrich Avatar
Rich Creedon
California, USA   usa

I think I polarized my generator backwards... My car is positive ground, I tried to follow the procedure on Moss tech video. Jumper between field terminal and Known Positive ????? Should I be jumping between field terminal and the chassis ? My voltage at battery goes from 12.5 V with engine off to 12.00 V with engine running. but my dash lite goes out when engine is started. I jumped from voltage source at starter solenoid ( this would actually be a Negative )to field....is that my mistake ??
Thanks for help !!!
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Steve S Avatar
On The Road, Lost in the California mountains, USA   usa
1925 Ford Model T
1939 Ford V8
1949 MG TC
1953 MG Y-Type Saloon
1958 MG MGA   → more

The method that has worked for me over the years takes about five seconds. Connect a length of 14-Gauge (or similar) wire to the 'A' terminal of the Control Box (voltage regulator). Quickly swipe the opposite end of the wire two or three times across the 'F' terminal on the back of the generator. The 'F' terminal is the smaller of the two. There should be a small spark.

That's it, you're done. Just be sure you do not leave the wire in contact with the generator for more than a split second, and do avoid touching it to anything else.




67mgbrich Avatar
Rich Creedon
California, USA   usa

Attempting to follow your procedure but voltage regulator does not seem to have an "A" terminal. Instead, it has the following: E, D, WL, F, B.

Does "A" translate into one of these letters?

Appreciate your input.

Thanks.
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
ozieagle Avatar
Herb Adler
Geelong Victoria, Australia   aus
1958 Wolseley 1500 "Wooly"
1966 MG MGB "Bl**dy B"

ALSO don't forget your tacho needs to be converted too.

Herb
67mgbrich Avatar
Rich Creedon
California, USA   usa

Please explain the tach ?? Are you saying it needs polarizing also ??
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
lars49 Avatar
Larry Barnes
Colorado Springs, Colorado, USA   usa
1959 MG MGA "Gramps"
1971 Norton COMMANDO 750 "Snortin Norton"
1980 MG MGB Limited Edition (LE) "Maggie"

Polarization is done by sparking the battery voltage to the field windings. In the case of the '67 MGB, with a positive earth, the negative battery terminal is connected to the B terminal of the regulator. This is the same as the A terminal in Steve's post. The field windings are connected to the F terminal on the regulator.

John Twist has a video on this as well as ways of checking your generator and regulator here:







Quis custodiet ipsos custodes?
67mgbrich Avatar
Rich Creedon
California, USA   usa

Thank You for clarifying the letters.
. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info
Steve S Avatar
On The Road, Lost in the California mountains, USA   usa
1925 Ford Model T
1939 Ford V8
1949 MG TC
1953 MG Y-Type Saloon
1958 MG MGA   → more

My apologies, I forgot that the MGB used a different letter set on the control box compared to earlier cars. The method is the same however.

The tach doesn't need polarizing, but it does need to be modified if you change between positive and negative earth. Connecting a positive ground tach to a negative ground system, or vice versa, will ruin the tach and require that you have it rebuilt.




. You can hide this ad & support this site by upgrading to a Gold Membership ~ click here for more info

Reply to this topic or post your own questions!

Members Sign In if you've already registered, or

Register a New Account

Registration is free and takes less than a minute

Having trouble posting or changing forum settings?
Check the Forum Help File (FAQ) or contact the webmaster.


Join The Club

Sign in to ask questions, share photos, and access all website features

MGExp Menu

What's New

Membership

Forums ->

MGB & GT

MG Midget

Buy, Sell & Trade

Vendor Market

MG Engine Swaps

Original MG

MGA

MGC

MG Magnette

1100 & 1300

T-Series & Prewar

Modern MGs

MG Motorsports

Member Meetup

MG 2015 Event

Other Vehicles

Off Topic

Clubs

Forum Search

Random Topic

Latest Posts

Live Chat

Calendar

Journals

Tech Library

Car Registry

Cars For Sale

Model Info

Motorsport

Directory

Member Map

MGExp Store

Search Site

Advertising Info

Smartphone quick link
mgexp.mobi

Adjust Text Size

Larger Smaller
Reset Save