54 m37, Not Charging, Field Tests?

[ke6rwj]

I verified that the truck is not charging... Voltmeter across the batteries shows 24 volts and doesn't change when running, not running..

Also shows "yellow" on the guage... i'm very sure its not charging

TESTING I HAVE DONE

I replaced the regulator about a year ago with a new military solid state one, I had the generator tested when i replaced the regulator, (year ago) they said it was fine... (pegged the needle they said... not sure what that means)

I have the "test" adapter.. but i'm not sure about the results of my tests...

What should i be testing and how?

The manual stated. . .

1) Remove the cable connecting the gen to the regulator
2) Insert the adapter to the gen
3) Connect a wire (shunt) from the ARM to the FIELD
4) Measure voltage from ARM to the gen ground (adjustment bolt)

I get nothing though...

"Replace and See what happens . . " advice is great when you can charge a customer for the parts, but not when its my checkbook.. before i spend $120+ on a regulator and twice that on a generator, id like to actually know whats broken..

thanks

Chris

 

[WarrenD]

Your test would seem to indicate that the generator has failed.

 

[ke6rwj]

buggers...! if you erase that comment and put something more positive in, will it fix my generator?

off to the gen-shop i go....

 

[ke6rwj]

genshop was no help. . . "Leave it with us, well test it sometime this week . . ." Uh nevermind...

pulled it apart, the brushes are nubs, and one was broken, so thats obvious...

Rebuild kit ordered...

stay tuned...

 

[WarrenD]

buggers...! if you erase that comment and put something more positive in, will it fix my generator?

off to the gen-shop i go....

Ok, Your test would seem to indicate that your regulator is not the problem.
Better???

 

[ke6rwj]

Ok, Your test would seem to indicate that your regulator is not the problem.
Better???

. . . doesn't seem to be a problem . . . . yet

apparently i'm breeding gremlins...

:0)

 

[WarrenD]

I know the feeling. I've had mine 2 weeks and the pinion seal weep turned into a leak and the radiator started leaking. It seems to leak more just sitting than it does driving (the radiator that is, though the pinion seems to leak about the same whether in motion or not)

 

[ke6rwj]

Update

I pulled the generator apart, and saw that one of the brushes was broken and worn down. i ordered a rebuild kit from midwest military and replaced the brushes, but it still didn't go. I had it tested at the generator shop and the armature is shorted... (a "growler" is an interesting device if you've never seen one work..)

anyway, i've got a couple junker generators to try and find a good armature..


I tested the regulator on another M37 and it was good, so i look forward to getting up and going soon...


I wanted to show some interesting junk that is out there for sale, I'm surprised that their is actually a market for this crap.

"Knock off" Vs "US Army" Voltage Regulator

Below are pictures of the two generators side by side... the differences are clear, but from a technical perspective, the official US one, is clearly better designed..

View attachment 278515View attachment 278516

Left side knock off, right Side "real" one..

some clear differences..

Knock off
- Label is clearly different, no contract name or company name of manufacturer, US Army goods usually have one or the other, particularly electrical items like this.
- label was not attached, real one is attached to the cover
- Screws were plain un-plated, they will likely corrode quickly, real ones are cadmium plated
- There are no "sealed" or painted screws on the knock off, this is how you can tell if its been opened..
- The knock off is missing many key parts, namely capacitor filters and has what look to be smaller wattage resistors. The power transistor is not a high quality heat tolerant version..

and amazingly its completely missing the big 50w resistor in the base! just what the heck are all the heat sink fins all over this for? there are no parts that are connected to it to dissipate heat.. they are just decoration.

View attachment 278517

I mean Really?!?!?

 

[ke6rwj]

ok so this was fun...

so like i said the armature was bad... i replaced that from a junker, but immediately got a call from the shop.. they said charged great for about 5 minutes, then the field coil shorted out... got any of those?

why sure, from the junkers i have... took some more junk to them...

now i have a Frankenstein generator, and it charges like a champ!... took 3 generators to make 1... i sure feel lucky

View attachment 279633

Moral of the story.... keep some junk around, you never know when you'll need it..