Ammeter reading

regor · Post by **regor** » Sun Feb 26, 2017 3:04 pm

Wes, may I jump in here with a question. Researching the posts on Ammeter, leads me to: The voltage and Amps from the generator have been checked and are functioning. The ammeter does not move. Even when the lights are turned on. Here I have read that an ammeter will not work with a transistorized regulator which my M38 has. I check the voltage at the ammeter according to the manual by disconnecting each wire, positive lead from voltage meter to the wire neg. to ground; checked both wires to the ammeter and have voltage on both. So my feeble mind tells me that the reason my ammeter doesn't work may be because I have the transistorized regulator and must replace the ammeter with an M38 volt meter? If so; there are two wires coming to the ammeter; please advise feeble person how to hook up the voltmeter with these two wires? thank you,

On another note: I see you inserted my album with my signature etc. Thank you, nice guy!!

Post by **wesk** » Mon Feb 27, 2017 1:54 am

What you have found is correct. Amp meters are used with old mechanical regulators and volt meters are use with the later transistorized regulators. The transistorized regulators do not have a shunted connection in them for wires #8 & #9 to use for an amp meter input.

mechanical regulator connections. Note: shunt installed between terminal pins A & B.

So just take wires # 8 & #9 and put dead end caps on them or just tape them up and tie them out of the way.

Since you do not want the volt meter to receive power with the ignition switch off you must choose a hot wire in the dash harness that is not hot with the master switch off. You have several choices for a Plus 24V lead to the volt meter:

1-Wire # 85 on the master switch is the easiest.
2-Wire # 27 feeds the instrument cluster spider harness from the master switch. You can replace your 4 wire spider with a 5 wire spider and use it for the Plus 24V to the volt meter.

Keep in mind that even though the volt meter is grounded to the gauge cluster panel it is still best to run a ground wire from the back negative terminal on the volt meter to the dash itself or the firewall.

regor · Post by **regor** » Mon Feb 27, 2017 8:49 am

Checking for a 24 volt, voltmeter for my M38; Walck list only the one with the colors to indicate condition. Looking for the one that indicates discharge or charge. Suggestions? Thanks!

4x4M38 · Post by **4x4M38** » Mon Feb 27, 2017 9:43 am

That's the only configuration I've seen the 24 volt voltmeters sold in.
Quick check shows Midwest Military, Peter DeBella, Army Jeep Parts all show
them, with Douglas or Packard connectors. Several on eBay, and I bet
Ron Fitzpatrick and Saturn Surplus all have them.

Post by **wesk** » Mon Feb 27, 2017 11:30 am

Looking for the one that indicates discharge or charge. Suggestions?

Both the amp meter and the volt meter can indicate a charge or discharge condition.

The amp meter displays the rate of charge or dis-charge in current flow direction only with no regard for voltage reading.

The volt meter indicates voltage at all times. You simply assume that if the meter reads less than 25.0 volts there is a discharge condition and if the volts are 27 or greater there is a charge condition.

If you want both indications you will need to install BOTH an amp meter & a volt meter. The military marked their voltmeters in red/ yel / grn for quick reference.

The only way to utilize a military amp meter with the transistorized voltage regulator is to add a shunt across the main current supply.

There's a good reason amp meters are seldom found in vehicles and aircraft today. The volt meter provides a great deal more information then the amp meter ever did.

If you want a numbered volt meter you can often find one in the military surplus pages for radios and electronics. Or you can just purchase a brand new civilian volt meter that fits the hole.

regor · Post by **regor** » Mon Feb 27, 2017 12:23 pm

I admit I am not to bright so I want to be sure I understand the previous posts. I understand all that's been said about the functions of the ammeter and voltmeters. I've ordered a 24 voltmeter from Walck. I understand about acquiring B+ voltage downstream from the switch. I don't think I want to change out the harness from 4 to 5. So will wires with voltage to the other gauges suffice, i.e.: fuel? Or is there an easier place to get it? Those wire number don't mean anything to me, sorry about that. Thanks!

Post by **wesk** » Mon Feb 27, 2017 1:24 pm

As I already said the easiest place is wire # 85 on the ignition (master) switch. You must deal with wire numbers on the military vehicles. They do not used colored wires. They are all black with a simple to read metal ID tag on each of them.

You can see wire # 85 at the ignition switch.

If you want to use wire #27 you can see it here as item "T" (27). Just splice into it.

regor · Post by **regor** » Mon Feb 27, 2017 1:39 pm

That made this job much more simple for this simpleton. Thanks Wes. I don't know how much they pay you but your worth every cent.

I went back and looked at the pictures you posted and want to address the picture with the voltmeter gauge indicating - & +. Is that from an M38?

I went back again and found wire #85 at the ignition and with a little humor let me say that it would appear I would have to stand on my head to get to it and at 83 that's nearly impossible for me. Ok; I haven't looked yet. I will go to the shop and look tomorrow morning.

Post by **wesk** » Mon Feb 27, 2017 2:16 pm

I went back and looked at the pictures you posted and want to address the picture with the voltmeter gauge indicating - & +. Is that from an M38?

I didn't post any photos of a volt meter?

it would appear I would have to stand on my head to get to it and at 83 that's nearly impossible for me

You do realize you have two other options???

1-Remove the switches knob and retaining nut and let it hang out from under the dash to access the wires.

2-Remove the instrument cluster from the dash by turning the 4 fasteners a 1/4 Turn to the left and reach in to the #85 wire at the left side of the opening!

regor · Post by **regor** » Mon Feb 27, 2017 2:21 pm

Gotcha! I didn't realize your suggestions. I will check out your suggestions tomorrow. However; if it can be fixed with R&R I can do it. LOL

And-- i was referring to the picture here in above showing the dash gauges where the battery gauge is shown. What is this type of gauge, shown, name?

4x4M38 · Post by **4x4M38** » Mon Feb 27, 2017 2:28 pm

Or as in your other suggestion he could do a plug and play and replace
the four wire spider on the back of the gauge panel with a five wire.

In either case he'll either need a new jumper with one female Douglas and one male Douglas connector from #85 to the voltmeter or a new five wire
spider. Certainly the former is less than the latter.

I'm still wondering how complete and "original" his vehicle is.
He's already had the original regulator swapped out for a transistor unit.
Wonder what wire #85 is plugged into at present. We know it's not just
dangling out there hot.

regor · Post by **regor** » Mon Feb 27, 2017 3:01 pm

To answer 4x4, my 51 M38 is totally original except for the silly transistor regulator which was there when I purchased. I have the original mechanical regulator and an extra starter along with many other small spare parts, manuals, etc. to be sold with the Jeep. During my 83 years with all of the various antique and classical articles that I have restored, I have always been persistent with originality. Since you are wondering about other aspects of originality of my jeep (?) I must ask if you are interested in buying the jeep. If so I will be happy to share any and all information that you would require.
Thank you.

Post by **wesk** » Mon Feb 27, 2017 3:53 pm

Roger, That illustration is of an M38 standard Instrument cluster using the standard M38 amp meter.

regor · Post by **regor** » Mon Feb 27, 2017 4:50 pm

Yep! That's what I was trying to get at/to. The gauge's shown in above post show the standard M38 which is the same as so many through the years and the one I really wanted to get. One question; is this gauge different than a six or 12 volt gauge? 24 volts is new this old person. I called Carl Walck and ask him to send me the fancy colored one. I'll call tomorrow to see if he has the original one. Thanks for all of the info and pictures; I'll keep you informed as how this turns out. Have a feller in Fla. who is interested in my jeep. ++++

Whoops, I'm back. #@$%@, that M series amp meter won't work with the silly transistor. Start over, strike all above. nice evening. Tell me how big does your state bird really get to be?

Post by **wesk** » Mon Feb 27, 2017 5:05 pm

I only pictured both so you could see how each functions. You are correct to stick with the new volt meter you ordered already. Just use wire # 85 to hook it up. The back of the gauge comes two ways. Early Douglas metal connector or later Packard rubber connector

You will need to fabricate a connector of one or the other to connect the plus side of the gauge to the #85 wire.