hi lynn

you are correct in one respect the kill switch has been removed and wire inserted but it wasnt me the quad came to me with half the loom stripped so im clutching at strawss tbh

how do i do the other tests you desribe?

Simon
will take some pix tomoz of wot im working with

 

lynn
how can i quick test the kill switch to make sure thats working as it shud?

 

I copied the following procedure in from another post. Step 4 is the one you already posted where you got 50 volts AC. But it doesn't hurt to recheck it .

[BEGIN COPY]

To troubleshoot no spark problems on a 6 pin AC powered CDI it makes sense to start in the middle (the CDI), measure as much as we can and branch out from there. For the CDI to do its thing it needs power, a trigger pulse, and it must must be inhibited via the kill switch input pin.



1) Unplug the CDI. Turn the ignition switch on. Set all kill switches the the "run" position. In the wiring harness, measure the resistance of the kill switch pin to the ground pin on the 20K ohm scale. It should read infinite ohms (same as when the meter leads are hanging free and not touching anything). It should not read zero ohms (shorted). If you turn on any of the kill switches into the "kill" position the resistance should go to zero ohms.

2) Leave the CDI unplugged. Use a meter to measure the resistance of the AC ignition power pin in the wiring harness to the ground wire on the 2K ohm scale. You should read approximately 400 ohms. What do you measure?

3) In a similar fashion measure the resistance of the Ignition Trigger Pulse pin to the ground pin. You should see 150 ohms or so. What do you measure?

4) Switch your meter over to measure AC volts on the 200 volt scale. Leave the CDI unplugged. While cranking the engine, measure the voltage on the AC Ignition Power pin in the wiring harness to the ground pin. You should measure 40 to 80 volts AC. What do you measure?

5) Set your meter down to the lowest scale you have for measuring AC volts. 2 volts would be ideal, but some meters don't go that low. In that case use the lowest scale you have. While cranking the engine, measure the voltage on the Ignition Trigger Pulse pin in the wiring harness to the ground pin. You should measure 0.2 to 0.5 volts AC. What do you measure?

6) Now plug the CDI back in. Measure the AC voltage on the Ignition Coil pin to the ground pin using the 200 volt scale. If you have to, use a sewing pin to poke through the wire insulation and then put the meter probe on the sewing pin. But don't hold your fingers on the connection during the next test - there may be high voltage here when the engine is
turning. With the ignition on and all kill switches set to the "run" position, crank the starter motor. You should see voltages bouncing around at random values and the meter captures all or part of a spark event. What do you see?

[END COPY]

 

have a vx-80 redcat quad for the lil one, sometimes it runs and sometimes it doesnt i think i have it narrowed down to the cdi box... smack it few times and it usually will run until it gets wobbled a bit then it wants to die

i used test found in this thread and it reads 56v ac so id go on limb an say its a AC cdi 6 pin like in picture

now my question does anyone have a link to where i can buy a AC one? i have found 2 places online to buy and neither have listed weither what they have is AC or DC, also they are all number on the sites so wasnt sure which worked best for me, how would the no rev limiter ones fair for the quad?

any insight is appreciated

 

56 VAC does indicate an AC powered CDI.

AC CDI's are more common than DC CDI's. I've bought a couple off eBay and both worked fine. I ran them less than 5 minutes, then heated them up and picked off all the epoxy to reverse engineer them.

Why not ask the vendors whether they are AC or DC? They should know. If they don't know shop elsewhere.

But I have to say your symptoms don't sound like a bad CDI. You say you whack it around and it starts working... But the CDI module is potted solid with epoxy - nothing can move at all in that epoxy block through simple whacking. Differential thermal expansion coefficients could cause internal connections to make/break with changes in temperature, but simple whacking causing this would seem unlikely to me.

More likely is intermittent/loose connections at the CDI connectors. Look *very* carefully at the pins in the connectors. Make sure each pin grips its mate firmly. Try wiggling each wire while the engine is running to see if you can induce a failure.