thunderbolt trigger theory and operation

[68C15]

1971 50hp ser# 3011762

how does the trigger work? is it a hall effect or magneto-reluctance? if it fails how is it tested? specs?

 

[Chris1956]

Re: thunderbolt trigger theory and operation

Hall effect trigger. I have never seen a definitive test or specs for it. Tests consist of a test for every other part of the ign system, leaving the trigger as untested. If the system works, the trigger is good, if not ...

 

[Faztbullet]

Re: thunderbolt trigger theory and operation

It uses a ignition driver(magneto). It has 2 coils (high/low) speed in the distributor/driver. The coils feed the switchbox which has a rectifier inside. The switchbox internal capacitor charges 4 time per revolution from the magnetic rotor (positive cycles only). The switchbox SCR is triggered by the negative cycles(blue wire) thus allowing capacitor to discharge into coil. This switchbox does not use any voltage from battery or keyswitch as it grounds to kill. Applying any voltage to the red terminal will kill the switchbox.
To Test:
If you have no spark remove the salmon and brown wire from blue terminal of switchbox. Make sure plug wires are removed from sparkplugs and attached to a sparktester as engine may start. If you now have spark check the wiring harness,mercury switch or tach if installed.
If still no spark remove all wire from switchbox. With meter omh between the red and white wires and you should have 410-430 ohms(4.1-4.3 on Rx100 scale).
Next test between blue and white and you should read 10.0-11.0 ohms on Rx100 scale.
Lastly take a reading between all wires and driver housing and reisistance should read infinite.
If any readings do not match there is trouble inside housing,if all is ok the switchbox has failed...

 

[68C15]

Re: thunderbolt trigger theory and operation

^^^^^^
thank you. I'll test this tomorrow night.
I have a new switch box but want to make absolutely sure the problem is not somewhere else and fry my $300. (eek)

 

[68C15]

Re: thunderbolt trigger theory and operation

I did your test. again, thank you.

when I removed the salmon wire I had spark. I tested that wire for a short to ground with it removed. with key off I had 30 ohms (expected) and with key on I had 304 ohms. is this providing a path of least resistance to ground? I don't have access to a potentiometer in this range but from what I read and see on the diagram I believe it is.

I suppose my next task is to find a new switch. if I slowly move key I get varied readings indicating arcing contacts and/or worn cylinder.

 

[ickus454]

Re: thunderbolt trigger theory and operation

Hey, I just fought a 40hp installing new switch box and stator. What kind of issue are you experiencing?

 

[68C15]

Re: thunderbolt trigger theory and operation

died while underway, no spark. at least that is what I DID have. dealer will have switch on wednesday. $40

 

[SleekWolf]

Re: thunderbolt trigger theory and operation

Anyone know of similar tests for a 77-78 1150? Also it says to check tach if installed. If my tach isn't hooked up will it cause no spark??

It uses a ignition driver(magneto). It has 2 coils (high/low) speed in the distributor/driver. The coils feed the switchbox which has a rectifier inside. The switchbox internal capacitor charges 4 time per revolution from the magnetic rotor (positive cycles only). The switchbox SCR is triggered by the negative cycles(blue wire) thus allowing capacitor to discharge into coil. This switchbox does not use any voltage from battery or keyswitch as it grounds to kill. Applying any voltage to the red terminal will kill the switchbox.
To Test:
If you have no spark remove the salmon and brown wire from blue terminal of switchbox. Make sure plug wires are removed from sparkplugs and attached to a sparktester as engine may start. If you now have spark check the wiring harness,mercury switch or tach if installed.
If still no spark remove all wire from switchbox. With meter omh between the red and white wires and you should have 410-430 ohms(4.1-4.3 on Rx100 scale).
Next test between blue and white and you should read 10.0-11.0 ohms on Rx100 scale.
Lastly take a reading between all wires and driver housing and reisistance should read infinite.
If any readings do not match there is trouble inside housing,if all is ok the switchbox has failed...