Joined: Feb 25, 2006 Posts: 344 Location: Wichita, KS
Posted: Fri Nov 07, 2014 6:21 pm Post subject: generator-regulator adjustment- thanks to this forum
Hi,
I recently replaced a headlight on my 1951 M38 (original 24 volts) because the "old" one burned out. I went with a cheaper civilian 24v headlight and spliced Douglas connectors to a three-prong headlight plug. It did not last long. So I searched the forum here on headlights burning out. I found some sound advice from Wes. The connections seemed to be tight, the ground was good, but what about the voltage? I unplugged the headlight and found 29.6 volts! It was the same on both sides- don't know why the other headlight did not burn out. My M38A1 was also winking, so I checked the voltage at the headlights and found 28.2 volts.
It was then back to the forum to find advice on how to adjust the generator-regulator. After reading several postings and consulting the TM 9-1825B I removed the generator-regulator from the M38A1. These are the Delco-Remy brand that have the screw for the tension springs in such a position that they can be adjusted while the regulator is still in the vehicle. I removed the cover, filed the contacts and then loosened the tension spring of the voltage regulator 1/2 of a turn (the lesson from Wes is that there is a voltage regulator, a current regulator and a circuit breaker that make up the generator-regulator).
I reinstalled it (Remember to the disconnect the battery whenever you are messing with the electrical system!) and started up the jeep and found the voltage at the headlight to be 24.4 volts. I removed the cover and tightened the spring 1/4 turn. It is now at 27.2 volts.
I completed the same type of work on the M38 and with about 1/2 turn of loosening the tension spring reduced the voltage to 26.6.
The bottom line- this forum is a great source of information. Wes, you do not have to answer everyones problems individually to be of great assistance. Thank you and all the other participants on this forum for all that you do! The other thing- it does not take much adjustment on the tension spring to change the voltage output.
I hope this helps others on this forum.
Kendall _________________ 1951 M38
1952 M38
1952 M38A1
1942 Dodge WC-55
1951 M100 trailer
1942 Ben Hur trailer
Wes, you do not have to answer everyones problems individually to be of great assistance.
That's because guys like you do a wee bit of research first then if you haven't found the answer you were looking for you post the question here. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jun 14, 2006 Posts: 226 Location: Wijnegem Belgium Europe
Posted: Sat Nov 08, 2014 7:44 am Post subject:
I did the same some years ago.
I placed a diode to bridge the relais wich connect the generator with the battery.
So i couild rescue the original regulator.
I get ± 27 volt during charging, enough to load and save the batteries.
The voltage and current regulation relais stays Original.
I have a volt gauge and the needle stays in the middle of the green zone.
Erik _________________ 1942 GPW 71336 my son's jeep restored now
1951 M38 MC11891
1953 VW beetle (genuine german Käfer )
1957 fantastic wife
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