boomer

boomer

Well Known Member
Just replaced my Vans standard starter solenoid with a new Vans standard (both four post: two big, two small) that I ordered a few months ago when I started having intermittent starting problems. Engine is Vans IO-360 M1B with Sky-Tek starter.

The old solenoid had a diode jumper which went from the small S jumper to ground. The new one came without a diode. Do I need one? The Sky-Tec web site doesn't show a diode and the starter seems to work fine. If so, what diode do I get?

BTW, when I took off the old solenoid (haven't had a chance to test it to see if it really broken) the diode was broken in half in the middle of the ceramic section and was blackened. I am wondering if this was my problem and the broken jumper wire was grounding at times.

Thanks,

-John
 
The diode is optional, but it helps extend the life of the switches more than the solenoid. It's really cheap insurance.

This is what Skytec says -

When replacing a Master or a Starter solenoid that has two small terminals, find the wire connected to ground (airframe), cap it, insulate it and tie the wire back safely. Attach the other small wire to the new STS-M12/STS-M24 or STS-S12/STS-S24 solenoid’s S terminal.
If there is a diode between the two smaller wires, leave it in place.



In Skytecs case their instructions are generally for certified planes and the diode would be considered a part of the airframe, so they only mention it when it is attached at both ends to the solenoid. I would not expect it to be shipped with the solenoid. :)

Put one in. :D
 
PCHunt said:
I thought that the diode on the solenoid was to keep the contacts inside the solenoid from burning and pitting?? :confused:
Click to expand...

It really protects the switch - AeroElectric Bob can explain it much better than I can -

http://www.aeroelectric.com/articles/spikecatcher.pdf


However, if the "switches" are not really mechanical devices but are electronic ones, then the "expensive electronics" comment may be sort of correct - but probably already taken care of in the 'switch box'.

For less than $1 for the part (or $11 all fabricated from Vans) it's really cheap insurance. :)
 
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PCHunt said:
I thought that the diode on the solenoid was to keep the contacts inside the solenoid from burning and pitting?? :confused:
Click to expand...

No, the diode is installed reverse biased across the coil (electromagnet). There is no connection to the contacts. When the ignition switch is turned from on to off, the sudden disruption of the current causes the coil to generate a large reverse voltage, which can arc across the ignition switch contacts, pitting and burning them. The reverse diode shorts out this voltage.
 
BobTurner said:
No, the diode is installed reverse biased across the coil (electromagnet). There is no connection to the contacts. When the ignition switch is turned from on to off, the sudden disruption of the current causes the coil to generate a large reverse voltage, which can arc across the ignition switch contacts, pitting and burning them. The reverse diode shorts out this voltage.
Click to expand...

that is correct
also good idea to use relays with diode china made chip relays create many problems killing drivers in control devices
 
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