whats this thing?

[Gary]

ive got a 620 which came with a J15, points ignition and an external reg alternator. now it has an L with an internal reg alternator and electronic ignition

 

ive got some weird problems and while i doubt this thing would be a part of it, just wondering what it is and if its necessary

 

its wired from an IGN/ACC source to negative i think

 

[Farmer Joe]

is that the capacitor?

 

maybe a little deal to cut down radio noise?

[Gary]

dunno, if i bypass it the wire heats up when switched to ACC so if its not important it'll have to be disconnected entirely. ill leave it off see how it goes

[datzenmike]

Do not bypass a capacitor. That's a direct short. Just remove if in doubt.

[Gary]

sweet

 

why would there be a cap between negative and a switched positive? its a black/red wire that comes off the ignition switch

[datzenmike]

I think even the electronic ignitions have them too. When points open or the EI module suddenly looses it's ground through the coil the 12 volts doesn't just stop suddenly, there is always some high frequency sinusoidal 'ringing' produced, sort of like an echo. This echo, for want of a better word, ends up on the radio as a ticking sound that increases with engine revs. A capacitor will conduct an alternating current but not direct current. The capacitor will allow this high frequency alternating signal a path to ground and dampen it faster. This is an extremely simplified answer.

 

Just imagine the square wave form below as the voltage applied to the coil in an on off on off signal. Note the 'noise' component? The capacitor will 'filter' that out.

 

[Gary]

cool, i just found a spare that looks in better condition so ill keep it for now

 

thanks mike :)