M38A1 MRC 83 100 Amp system

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Spec4Don
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M38A1 MRC 83 100 Amp system

Post by Spec4Don » Fri Jun 24, 2022 8:51 am

I’m finally putting my radio Jeep back together. Down to the wiring harness. Is there any diagrams of the 100 amp system that label what wires go to the regulator? I have the diagram of complete setup in the Jeep but apparently mine had a much later system in it. The Jeep was partially disassembled and missing some parts when I got it. At this point I really just need it to charge the batteries.
Any insight would be helpful. If I could figure out how to excite the generator that would be great.

Don G
1942 M3 Halftrack Zelda MVPA # 31688
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egalecov2
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Re: M38A1 MRC 83 100 Amp system

Post by egalecov2 » Sun Jun 26, 2022 5:54 pm

Don,

I am guessing that your 100 amp system is using Leece-Neville components - like a voltage regulator with cast on cooling fins. This same system used an in front of radiator rectifier (air cooled) and a nest of braided wire jacketed connecting cables - generator to rectifier to voltage regulator. This system was intended to handle multiple radio sets. So how much of this 100 amp system do you have and how much of it do you want to restore? I do not have a TM answer for you.

Ernie

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Spec4Don
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Re: M38A1 MRC 83 100 Amp system

Post by Spec4Don » Sun Jun 26, 2022 7:42 pm

egalecov2 wrote:
Sun Jun 26, 2022 5:54 pm
Don,

I am guessing that your 100 amp system is using Leece-Neville components - like a voltage regulator with cast on cooling fins. This same system used an in front of radiator rectifier (air cooled) and a nest of braided wire jacketed connecting cables - generator to rectifier to voltage regulator. This system was intended to handle multiple radio sets. So how much of this 100 amp system do you have and how much of it do you want to restore? I do not have a TM answer for you.

Ernie
I pretty much have everything but the radio it’s self. Most of the collins wiring is there. I have the alternator, rectifier, and regulator as well as the connecting cables. At a minimum I need it to charge the batteries. I have a copy of the wiring on the Jeep. But it is too blurry to really tell where the wires run. I was in contact with Paul V but his email isn’t valid any more.

Don G.
1942 M3 Halftrack Zelda MVPA # 31688
Clark CA-1 Airborne Dozer
Letorneau Model D-4 Airborne Scraper

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Spec4Don
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Re: M38A1 MRC 83 100 Amp system

Post by Spec4Don » Fri Jul 08, 2022 7:20 am

Getting closer, on the wiring, but still looking to fill in the blanks. Someone must have some info on the collins wiring!

Help!
Don G.
1942 M3 Halftrack Zelda MVPA # 31688
Clark CA-1 Airborne Dozer
Letorneau Model D-4 Airborne Scraper

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Re: M38A1 MRC 83 100 Amp system

Post by Spec4Don » Tue Jul 12, 2022 7:16 am

With bits and parts of info I think I have come up with a wiring plan, hopefully it will work.

Image

Image

Image

Don G.
1942 M3 Halftrack Zelda MVPA # 31688
Clark CA-1 Airborne Dozer
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Re: M38A1 MRC 83 100 Amp system

Post by mdainsd » Wed Jul 13, 2022 7:06 am

Be careful ! Some of the wiring you show is in real sketchy condition. You do not want a short circuit.

The wiring, if original, is fairly straight forward. Note: there seems to be several modifications to the wiring, like the big resistor on the fire wall.

Cable one. goes from the generator to the rectifier (3 large pins, three small).

Cable two goes from the rectifier to the regulator/ (2 large pins. 5 small).

The regulator hooks to the vehicle cable (we will call it cable three), which appears to be the one draped over the engine to the passenger side with a Bendix connector in it.

Before proceeding need to know how many wires It has (looks like only two large white ones?). Also is it the one that would fit into the second connector on the regulator?

I might be able to help more after you report on that connector/

Mark
52 M38 2X, '52 M37, '44 WC51, '42 WC 56/57, '50 CJ-V35(U), '42 GPW, '44 M3A1 Scout Car, 2010 M-Gator

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Re: M38A1 MRC 83 100 Amp system

Post by Spec4Don » Tue Jul 26, 2022 5:15 am

Hi Mark, the 2 big white wires are labeled, positive and negative respectively. According to what I’ve read the “F” pin is the Field wire. The second small wire is is unclear what it does. I’ve repaired the small wires. I have run the vehicle but I’m not sure if it’s charging. I’ve been chasing some other issues on the Jeep. Any help is greatly appreciated.

Don G.
1942 M3 Halftrack Zelda MVPA # 31688
Clark CA-1 Airborne Dozer
Letorneau Model D-4 Airborne Scraper


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