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M. Relay post too short for diode

A

alpinelakespilot2000

Well Known Member
Another one of those problems I've been putting off, but can't any longer...

The post on my (Vans) master relay is not long enough both for the diode (supplied by Vans) and the wire coming for the master switch on the panel. As the picture shows here, not only do I not have a washer under the nut, the nut itself barely fits on (with no threads left over). Any ideas about the best way around this problem?

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Fairly common problem. You may also be able to replace the inner nut and washer with thiner one's and locktite the outer nut sans lockwasher.

Larry
 
IIRC

Maybe I am just having a senior moment here, but doesnt the large ring on the diode go under the mounting bolt, not the power terminal as shown??

As I recall, the diode is to dump the induced voltage out of the coil, when it is switched off.

I used a contactor with an internal diode, so did not actually have to hook up one on my plane.
 
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Master vs Starter relay diode installations

The starter solenoid uses the diode from the small relay control stud to the mounting bolt, with the diode band on the small stud side of the diode.
The master solenoid uses the diode from the small relay control terminal to the large terminal marked BAT. The band of the diode should be on the large terminal side.
There is a diagram in VAN's electronic catalog under the electrical section that you can look to for guidance.
 
sf3543 said:
The starter solenoid uses the diode from the small relay control stud to the mounting bolt, with the diode band on the small stud side of the diode.
The master solenoid uses the diode from the small relay control terminal to the large terminal marked BAT. The band of the diode should be on the large terminal side.
There is a diagram in VAN's electronic catalog under the electrical section that you can look to for guidance.
Click to expand...
Yes, it depends on whether you are powering a contact or switching it to ground. When the item is a coil (as in a solenoid) the current wants to keep flowing when the switch is turned off. Without the diode it will arc across the switch terminals. The diode allows it to keep flowing and die off gracefully with out wrecking your switch.
 
So, if I understand all of the above, my diode is oriented correctly, right?

Any other ideas for getting both on one post? So far the splice sounds like the best option, but I'll have to see what's under the yellow shrinkwrap to see if there's enough regular wire to allow me to cut off the existing terminal and add a new one.
 
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alpinelakespilot2000 said:
So, if I understand all of the above, my diode is oriented correctly, right?

Any other ideas for getting both on one post? So far the splice sounds like the best option, but I'll have to see what's under the yellow shrinkwrap to see if there's enough regular wire to allow me to cut off the existing terminal and add a new one.
Click to expand...

Yes the diode is oriented correctly. If you decide that you need a new diode so that you can crimp new ends, pick up a 1N5400 series 3A diode from radio shack and make a new one.
 
MS35333-39 washer

I removed the funky, thick, automotive lock washer and replaced it with a thinner MS35333 aircraft washer.
 
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