[dhcarguy]

My amp gauge stopped working. It looks to have moisture behind the glass. What could have caused this??
Is it repairable??

[dhcarguy]

Why do my pictures turn sideways??

[steve25]

Amp gauges are wired in series with a main hot wire so even though it stopped working it's still passing power to the whole car's electrical system but for the starter circuit.

My guess is that the moisture in the gauge has corroded the meter movement and its hanging up the pointer from moving.

There are folks who can rebuild it for you.

["QUICK-SILVER"]

Is that moisture or smoke stains?

If you run more amps through it, than the gauge can handle, it will smoke/melt the windings and quit working.

Clay

[dhcarguy]

Originally Posted by "QUICK-SILVER"

Is that moisture or smoke stains?

If you run more amps through it, than the gauge can handle, it will smoke/melt the windings and quit working.

Clay

What would cause more amps than it can handle? I have not done anything to change that, that i am aware of.
Thanks guys, Dave

[Shiny]

Probably not water if it has a permanent haze. Water would clear up (condensation and evaporation are reversible). If water got in, it can get out.

More likely a material with a low vapor pressure (plastic, lubricant) that condensed or smoke particles that wanted to stick to the glass. If this is the cause for the haze it suggests something inside got pretty hot but I'm clearly speculating.

It does seem weird for it to not work but still pass current. I don't know anything about the design though.

[1968GTO421]

Originally Posted by steve25

Amp gauges are wired in series with a main hot wire so even though it stopped working it's still passing power to the whole car's electrical system but for the starter circuit.

.

This^. Most guys I know use a voltmeter instead of an ammeter since only a small wire with small amounts of electicity go through it. Voltmeters are considered to be safer than an ammeter. Yours is an underdash unit so easy to replace.

["QUICK-SILVER"]

Cars with factory amp guages had a shunt between alt output and B+. The shunt was a resistance wire that made partial amp flow actually go through the amp guage. The guage was calibrated to show full + or - charge while only reading a small portion.

The magnet wire windings in the aftermarket guage are tiny compared to the cars bat and charge wires. The more amps the guage reads the hotter the coil gets. If the coil shorts out from varnish burning off the magnet wire, you still have amp flow but the coil wont generate enough magnetic field to move the needle.

This guage may have resistors in it also. They can give up/fail the same as varnish coating on magnet wire. Neither can heat up, too hot, but so many times.

Too many amps is more than what the guts in the guage can handle. What the guage can handle has probably been reduced by old age, time, heat, etc..

It just happens
Clay

[george kujanski]

^^^^^^ this

There is a shunt in the harness so only a portion of the total current goes thru the gauge. Aftermarket ammeter kits usually run the full current thru the gauge..avoid those, use a voltmeter if ever considering an aftermarket ammeter.

George

[dhcarguy]

Originally Posted by george kujanski

^^^^^^ this

There is a shunt in the harness so only a portion of the total current goes thru the gauge. Aftermarket ammeter kits usually run the full current thru the gauge..avoid those, use a voltmeter if ever considering an aftermarket ammeter.

George

I know NOTHING about electrical components. If I went with a volt meter instead of an amp meter, would I use the same wire that is on my amp meter??

[george kujanski]

A voltmeter is connected from a circuit that is ON when the key is ON and the second wire to a good metal dash connection. The wires on your existing ammeter may be live even when the key is off so those are not suitable for a voltmeter, as the voltmeter may drain the battery slowly with key using that circuit.

There may be a terminal on your fuse box that is live when the key is on, such as ACC (accessory).

George

[dhcarguy]

[QUOTE=george kujanski;6117683]A voltmeter is connected from a circuit that is ON when the key is ON and the second wire to a good metal dash connection. The wires on your existing ammeter may be live even when the key is off so those are not suitable for a voltmeter, as the voltmeter may drain the battery slowly with key using that circuit.

There may be a terminal on your fuse box that is live when the key is on, such as ACC (accessory).

George[/QUOTE

Got it! , Thanks George