70 ammeter repair
Thread Starter
Le Mans Master
Joined: Jul 2006
Posts: 8,117
Likes: 104
From: charlotte north carolina
70 ammeter repair
my ammeter was bad, showed open circuit across the terminals, so i said" what the hell ,it's broke anyway". i removed the pointer, drilled out the two small rivets that hold the face to the gauge, and pushed the mechanism out of the housing. i expected to see hundreds of turns of a very fine wire (from previous experience), but found only about twenty turns of relatively workable wire. close inspection showed two melted tips of wire with little ***** of melted copper at each end. i unwound the two tips a half turn each, cleaned the insulation off the wire and soldered them, put a dab of paint on the joint, and reassembled with gorilla glue.
the delection may be slightly less than befofe due to the one less winding, but it works ok.
the delection may be slightly less than befofe due to the one less winding, but it works ok.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Noo, upgrading the alternator will not cause any dammage to the ampmeter. The meter only measures the current going thru the wire coming from the alternator. Upgrading the alternator will not change the current, adding big current devices to the existing system WILL increase the current thru the same wire which will cause more meter deflection, but will not dammage it. The meter is designed to deal with full meter deflection all the time, thats 50 or 60 amps. The system rarely sees that kind of current draw. The meters get dammaged when something happens to the wire that is supposed to carry all the current, lose connection with a load on it. The amp meter is actually a very sensitive voltmet that measures the voltage drop across a piece of wire with a known resistance, the meter deflection + or - is in relation to the voltage drop that is in relation to the current going thru the wire.
was that confusing enough?
was that confusing enough?
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Noo, upgrading the alternator will not cause any dammage to the ampmeter. The meter only measures the current going thru the wire coming from the alternator. Upgrading the alternator will not change the current, adding big current devices to the existing system WILL increase the current thru the same wire which will cause more meter deflection, but will not dammage it. The meter is designed to deal with full meter deflection all the time, thats 50 or 60 amps. The system rarely sees that kind of current draw. The meters get dammaged when something happens to the wire that is supposed to carry all the current, lose connection with a load on it. The amp meter is actually a very sensitive voltmet that measures the voltage drop across a piece of wire with a known resistance, the meter deflection + or - is in relation to the voltage drop that is in relation to the current going thru the wire.
was that confusing enough?
was that confusing enough?
6' in fact according to elementary electrical/tronic theory you are correct, BUT, in my '72 here if you read the schematics closely you find that meter is not a typical series/shunt AMP meter....all it does with thin wires...being black and black/wh trace is indicate the amount of power/voltage differance the regulator is trying to force into the the total load......
it's 'electronic' in other words....and as such wired the way it is, has no particular bearing on any aftermarket mods and how they react with anything differant than a total stock setup....stereo, fans, lights, etc....
which is why when I got my car and finally got around to doping out what in hell was WITH that thing, I put a VOLTmeter in it's spot outta a mid 80's chebby pickup.....looks damn close to my '72 anyway....
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
So a 72 has an external regulator? I guess I am not understanding how its connected. I been thinking about getting a couple more vette shop manuals so I can take a look at that kind of stuff
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Much tooooo much tooo many decades 4 me to remember all that, I do remember my buddy's '68 goat had a firewall regulator for his ALTERNATOR.....the connector is ]] instead of -- if you look close at the '72 chebby manual, covers vettes as well as rest of the '72 lineup, you find the vette section is in slight error, in that I have that manual open right now, under glass in the kitchen....and I swear there is a published documentation error....maybe messed up, but I don't think so....it's confusing has hell to look at being over 3-4 pages of schematics.....
it involves a blach/wh and brown wires.... and a black wire coming back from the ampmeter to....
and that's where it get lost....
I vaguely remember some crap about this years ago when first figgering out this 'ampmeter' in my '72 here, and remember doping out what in fact was going on...so much so I tore the freeking harness apart under th hood, determined to FIND it....stayed that way till '01, when I rewired the entire car....
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
I also dumped the ammeter and use a voltmeter from a 78 I think with an early orange needle. Works great.
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