What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Light Speed Plasma III CDI troubleshooting

bomber_JB

Active Member
I have no spark when I rock prop back and forth rapidly at TDC.

Troubleshooting steps:
I've verified the 1 OHM btw center conductor and shield when connected to coil.
I've verified an open circuit btw the spade to output terminal as it should be.
I've verfied 14VDC at pins 8 and 15 on the input D-sub.
I've verified my sensor gap is 0.040.
I have more than 1/2" separation btw sensor wires and output wires.


I'm trying to verify 5V is present on pins 4 & 5 per Section 7 troubleshooting.

Can someone help me understand how to do this when the input D-sub would be connected. Do I go into the back of the D-sub with tiny feelers from my multimeter?

The next step in trouble shooting is to verify there is 5V at the input pins and that it drops to about .1 V twice per revolution. Again. How do you do this with Input D-sub connected.

Thanks,

Jerry
 
Take the back-shell off the input connector(s) and probe Pin 4 & 5; use the sharpest probe you have to penetrate the clear shrink wrap that he uses...
 
I have no spark when I rock prop back and forth rapidly at TDC.

Troubleshooting steps:
I've verified the 1 OHM btw center conductor and shield when connected to coil.
I've verified an open circuit btw the spade to output terminal as it should be.
I've verfied 14VDC at pins 8 and 15 on the input D-sub.
I've verified my sensor gap is 0.040.
I have more than 1/2" separation btw sensor wires and output wires.


I'm trying to verify 5V is present on pins 4 & 5 per Section 7 troubleshooting.

Can someone help me understand how to do this when the input D-sub would be connected. Do I go into the back of the D-sub with tiny feelers from my multimeter?

The next step in trouble shooting is to verify there is 5V at the input pins and that it drops to about .1 V twice per revolution. Again. How do you do this with Input D-sub connected.

Thanks,

Jerry


Sometimes, if you don't go fast enough, it will not work (had the same problem once). Pull the plugs out, and crank the engine with the starter (with the plug leads off the output of the coils) and you should definitely see a spark then.
 
To echo the previous post, when I did this, I pulled all the plugs and spun the prop rapidly by hand. I was able to see each coil jump a spark in the firing order. Speed may be the issue.
 
It’s been a while since I did this. You don’t mention where your spark plugs are when you do this. They need to be grounded to the airframe for it to work if I’m not mistaken. I had mine laying on top of the engine, making sure there was metal to metal contact.
 
You don't need plug wires attached to test a Lightspeed spark. With no plug wires attached to the coil, the spark will jump the gap between the 2 output terminals when there is energy.
 
You don't need plug wires attached to test a Lightspeed spark. With no plug wires attached to the coil, the spark will jump the gap between the 2 output terminals when there is energy.

That’s the best way to test the plasma iii and also tests phasing and proper hookup to input and output channels. Important to verify spark at coils if there’s a question at all. You can actually rock the prop back and forth to verify the spark. I’ve had to do this when I changed from crank sensor board to top mounted sensor.
 
Back
Top