CDI ignitions

[Michael]

I assume most of us are aware that these fail on a regular basis. I also assume that whatever fails is some simple diode or the like which probably costs pennies to replace. Has anyone ever dug into a failed Mark III or IV ignition and figured out what normally causes them to fail? There has to be a better way then replacement at GBP50 plus every time.

[Daryl]

Generaly in my experience of Johnson/Evinrude the SCR in the CDI unit is what fails.

[Adrian Dale]

SCR?? may be I should know but don't..

AJ

[Daryl]

An SCR / Thyristor is a Silicon Controled Rectifier or a switching device, which is used in the circuit of a CDI ignition system.

[Collector Inspector]

Generally with a Gull when these fail...no any good news.

What someone has to do is dissolve the potting and lay bare the electronic simple and cheap parts that populate such magic black smoke and mirrors things.

Generally a fair soak in nail varnish remover or acetone turns the potting hard stuff to jelly after a while.

Messy business if you are into that.

Once laid bare, bits are readily available component by component within. http://www.rs-components.com/index.html

Upgrade the individual bits and re seal with potting. Then the coil/coils may be stuffed and take out what you replaced.

Old Chestnut this aye.

Most times Gull electronic ignition is fine but sometimes...

B

[Charles uk]

Does the nail varnish remover or acetone affect the insulation on the coil windings?

[Collector Inspector]

Does the nail varnish remover or acetone affect the insulation on the coil windings?

No effect.

B

NB: This is a slow process soaking in say acetone waiting for the potting to turn to jelly. If one was too keen and impatient the coils could be damaged due to trying to pick out the jelly too soon. The insulation of the coil wire in that case could be mechanically abraded so time is the key. The acetone else wise has no effect on insulation.

[Charles uk]

Is that why they make shellac acetone nail varnish?

[Collector Inspector]

Interesting using a shellac based wire insulation.

I guess that my "Un-potting" of electronics in the past must have had a polymer/co-polymer insulation on wee wound components.

I have never needed to deal with these Seagull items before.

I suggest that Gull electronics should be replaced and not repaired.

Thank you for the correction Charles.

Cheers

B