1950 M38 no reading on the dash amp meter

radtech · Post by **radtech** » Sun Apr 21, 2024 4:49 pm

The generator is charging 30 volts but no reading on the amp meter

4x4M38 · Post by **4x4M38** » Sun Apr 21, 2024 5:04 pm

The amp meter only shows load, correct? Do you have anything turned on?

The voltmeter if you had one shows generator output continuously.

Maybe I’ve been out in the sun too long today….

RonD2 · Post by **RonD2** » Sun Apr 21, 2024 6:47 pm

With the engine not running, turn the headlights on.
Do you see the ammeter needle jump part way to the negative side indicating the load on the batteries?

radtech · Post by **radtech** » Sun Apr 21, 2024 7:50 pm

I think the armature in the meter is locked up.It doesn't move with the lights on or when running the radio gear.Is there any source for these amp meters.It is a Dec.1950 mfg and I would like to keep it original.

radtech · Post by **radtech** » Sun Apr 21, 2024 8:22 pm

Found one on ebay NOS.

G740 · Post by **G740** » Mon Apr 22, 2024 5:50 am

What voltage regulator are you running? Solid state or mechanical?
John

Post by **wesk** » Mon Apr 22, 2024 9:33 am

You mentioned your radio gear. Most jeeps with radio gear had the larger output generators or alternators. Most conversions to these larger power output units included a switch from amp meter to voltmeter. This would be a good time to give us a accurated component assessment of your electrical system. Stock, 60 Amp or 100 Amp or civilian system.

radtech · Post by **radtech** » Mon Apr 22, 2024 12:20 pm

Current draw is only around 8 amps in receive and 12 in transmitt.It has never affected the batteries.

Post by **wesk** » Mon Apr 22, 2024 12:36 pm

So, is your electrical system completely stock and original? Including the voltage regulator? The Army introduced a transistorize voltage regulator around 1959. Also a Delco generator and regulatyor were optional. When you first start the jeep does the amp meter show a positive charge then taper off to the middle neutral position?

RonD2 · Post by **RonD2** » Mon Apr 22, 2024 4:31 pm

radtech wrote:I think the armature in the meter is locked up.It doesn't move with the lights on or when running the radio gear.

What makes you guess the meter armature is "locked up"?
Because the needle doesn't move under any condition?

Did the needle ever move in the past and just recently quit?
Or --- it never worked?

You have to answer all the questions asked if you want constructive troubleshooting help.

radtech · Post by **radtech** » Wed Apr 24, 2024 10:49 am

The needle has never moved and the resistance through the meter shows a complete circut.I put a battery to the meter and the needle still doesn't move.

Post by **wesk** » Wed Apr 24, 2024 11:46 am

Radtech, could you answer this question I asked above earlier?

PostPosted: Mon Apr 22, 2024 12:36 pm Post subject: Reply with quote Edit/Delete this post Delete this post View IP address of poster
So, is your electrical system completely stock and original? Including the voltage regulator? The Army introduced a transistorize voltage regulator around 1959. Also a Delco generator and regulatyor were optional. When you first start the jeep does the amp meter show a positive charge then taper off to the middle neutral position?

radtech · Post by **radtech** » Wed Apr 24, 2024 12:35 pm

Wiring from regulator to amp meter read good.Regulator is Autolite VBC 4002UT.I also checked the meter shunt resistor in the regulator which I thought might be the problem it is good.

Post by **wesk** » Wed Apr 24, 2024 8:41 pm

And an answer to this questions as well:

When you first start the jeep does the amp meter show a positive charge then taper off to the middle neutral position?

Also is the generator Auto-Lite as well????

Also have you had the regulator and generator bench checked by an automotive electrical shop?

radtech · Post by **radtech** » Fri Apr 26, 2024 7:58 pm

New amp gauge solved the problem.A couple taps with a plastic mallet and the old one now works.