CAV control box issues and Fuses....

[Richard Farrant]

Originally Posted by rmgill

Two problems...

One, Vandal has a charging system problem.

The generator is getting 2 or less volts on field current and not putting out any voltage. It does put out voltage if I jumper B+ to Field for a moment, upwards of 20 volts (I don't do that for very long).


Two, in the process of troubleshooting this I managed to blow the main fuse and we have no more. Anyone know where I can get the CAV type 50 amp main fuse from? It appears to be lead, I was thinking of making a replica out of 1/2 the thickness .005 brass sheet and then tinning it to see if that would work (start smaller). But, I'd rather use a proper thing and not have the risk of frying wiring I spent so much time installing. So, does anyone know where the CAV clip on fuses may be had from?

Ryan,

If you go to the workshop manual it explains the tests to be carried out, one like Lynn says, is to motor it over, a good basic test. Could be a dirty commutator, or sticking/worn brushes, or presence of oil or grease. As for the fuse, don't think it is lead, should be a thin aluminium, easiest thing is to source some fuse wire of 50 amps rating.

[rmgill]

Originally Posted by Richard Farrant

Ryan,

If you go to the workshop manual it explains the tests to be carried out, one like Lynn says, is to motor it over, a good basic test. Could be a dirty commutator, or sticking/worn brushes, or presence of oil or grease. As for the fuse, don't think it is lead, should be a thin aluminium, easiest thing is to source some fuse wire of 50 amps rating.

I'm thinking that there's a problem with an open lead on the back side. Though, when we swap the fan belts out for a slightly smaller size, we'll motor the generator tomorrow.

I've tried cleaning the voltage and current bobbin contacts. They appear good however.

So some more data here and more correct....

Field at the CAV box shows .2-.5 volts or there abouts.

The P lead shows ~1.8 volts for the green "not charging" indicator lamp.

The D+ lead shows 2 volts.

The Voltage and Current Bobbins are both closed and do not stutter. The Field cutout bobbin is open and does not close on it's own.

If I engage the cutout bobbin, I get battery line voltage on the generator and of course it's acting as a motor, apparently.

If I engage the cutout bobbin while the engine is off, the generator of course can't spin and the bobbin locks closed and then it releases when the fuse blows.

I'll take the unit out tomorrow so I can examine it on a bench more clearly. It would seem that there's no voltage on the current/voltage bobbins.

Lynn, it very well could be running up past 20 volts I just didn't want to see if I could let the smoke out by letting the voltage climb. Needless to say the generator seems to function if it gets enough field current. I did try a lower voltage from the P connection and got a lower rate of voltage climb.

RE the fuse,
I've managed to make a stand-in fuse out of .005 thick brass of the same shape and size. That should carry a bit less current and act reasonably well. I'll find some aluminum of the right thickness and carry out some better tests.

[rmgill]

The generator does motor quite fine. I'm suspecting that since it's not seeing a substantial voltage from the field terminal that there's some issue with the wiring. Dave Page and I went over his manual's notes for the 141 CAV box and it has me suspecting a fault there. I'll have to do a component by component check of the box.

Thanks for the advice so far!

[Lynn Eades]

So what happens if you jump straight from the battery to the field terminal?(bypass the fuze box)

[rmgill]

Originally Posted by Lynn Eades

So what happens if you jump straight from the battery to the field terminal?(bypass the fuze box)

That was one of the first things I tried. With the DMM measuring the voltage output of the Generator, I see a very rapid rise in voltage past 20 volts from the D+ and D- connections.

12 volts on to the field connection sees a rapid rise.
2 volts from the P terminal sees a similar rise but not as rapid but it still goes up dramatically and, not wishing to make things blow up in my face I discontinue the function. I also get a modest spark when I disconnect the jumper but it's not enough to mar my jumper, it's also a small 18 gauge jumper so it won't carry a lot of current (smallest in the link of the chain).

[Lynn Eades]

I'd guess that the problem is a regulator problem.

[rmgill]

Pretty much what I'm thinking.

The contacts DO look clean but I could be mistaken. I cleaned them carefully with plain paper AND with a bit of contact cleaner.