706 electrical problems-Help needed

I have a 1967 Farmall 706 with a German diesel engine. Last spring (around April) I replaced the alternator and voltage regulator due to a charging problem. Then in July the charging problems started again. I had the dealership work on the tractor because I was out of ideas of what the problem maybe. They ended up replacing the alternator and voltage regulator again. That seemed to fix the problem. Then in October the charging problem returned again. I had the alternator tested and the alternator was bad again. I replaced the alternator. It fixed the problem. I was getting the tractor ready for spring today and I noticed the charging problem is back. I think the alternator has gone bad again. I am going to have it tested tomorrow. What would cause the alternator to go bad so many times? Any ideas would be greatly appreciated.

TJH72

If you are not getting poor quality rebuilt alternators, or have high electrical demand due to added accessories, the most likely problem is faulty wiring. Excess voltage will cause failure due to over heating. Those alternators will fail if run at maximum output for too long a period of time.

A poor connection can cause the regulator to demand maximum output from the alternator. Inspect the main wire from the solenoid battery post to the alternator output stud. Make sure that you do not have a poor connection between the connector and the wire. If that wire is good you should be boiling the batteries if the voltage is too high. Inspect the junction block and the wires going from the solenoid to the junction block, to the regulator. A poor connection there can cause low voltage at the regulator which again will cause the regulator to demand higher voltage.

With the system working you should not see more that 15 volts at the alternator output terminal, usually less than 14.5 volts. You should have no more than .1 volt drop across any connection. If you have .5 volt difference from the alternator output to the battery terminal on the regulator you are going to have problems.

I would junk the externally regulated alternater and replace it with a internally regulated delco alternater. Its a simple bolt in converson with simple wiring changes to make your idiot light work. You can use a one wire alternater but your charge light will not work. I installed one on my 756 german diesel. Cheaper and lots less wire conections to cause trouble.

I have had to adjust the voltage on the regulator on these because new they were putting out 16v.Ajusted down to 14.8v and quit boiling the batterys.

How do you adjust the voltage on a regulator?

Thanks,
TJH72

Here is a wiring diagram to put in a reliable internally regulated alternator Delco SI 10
The diode shown can be replaced by the idiot light. The idiot light must not be grounded, each lead must go to one of the leads as shown going to the diode. JimN

Adjusting an "external" regulator [Delco] can be done if you can remove the cover. You have to have an analog voltmeter to read volts---not a digital. With the cover off, find the "contact" that controls the field. The coil will control a movable contact plate that can touch either of 2 stationary points on the frame of the coil. With the engine running, use a finger to move the contact up & down while watching the voltmeter. The "up" position delivers maximum output--the"float" position --in between --& not touching either point will give ordinary load charging. When touching the "bottom" contact it will give 1 amp of charge.
Set the movable contact-- by adjusting the spring tension-- for 13 to 13.4 volts on a fully charged battery. This is the "float" position.