Symptoms of a bad Slick Magneto Capacitor?

[Gary0747]

Mags came off for 500 hour inspection. We tested the capacitor on each and found one that was bad showing very low resistance.   I saw no apparent symptoms of a bad mag while flying prior to finding this.  Does anybody have experience with seeing how a bad capacitor effects engine performance?   

[Mjknick@gmail.com]

Mags came off for 500 hour inspection. We tested the capacitor on each and found one that was bad showing very low resistance.   I saw no apparent symptoms of a bad mag while flying prior to finding this.  Does anybody have experience with seeing how a bad capacitor effects engine performance?   

Bad capacitor will cause points to arc and burn and go bad.



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[Guest]

And overheat the plastic cam, melting it causing the mag stop making sparks.

Clarence

[Guitarmaster]

Making Sparks good.... No make Sparks, bad.

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[RLCarter]

While the mags are off why not just replace the points and capacitors?

[Hank]

12 hours ago, Guitarmaster said:

Making Sparks good.... No make Sparks, bad.

BTDT. No make sparks awaynfrom home, More Bad!

Never have understood why it's acceptable for an A&P to take advantage of travelers in distress . . . . My out-of-town mag removal, ship off for overhaul and reinstall was > 1.5 AMU . . . .

[carusoam]

Wait a minute...

How did you/they test the capacitor?

Resistance of a capacitor?  Or capacitance?

I thought their resistance was supposed to be infinite...   electrons are stored on internal surface area... if they leak through to the other side, they drain out...

Might be a typo, or my misunderstanding? 

PP thoughts only, not a mechanic...

Best regards,

-a-

[Gary0747]

Slick manual in the 500 hour inspection specifies the resistance between the capacitor case and main terminal.   It also specifies the capacitance. 

[thinwing]

On 6/1/2019 at 11:07 AM, carusoam said:

Wait a minute...

How did you/they test the capacitor?

Resistance of a capacitor?  Or capacitance?

I thought their resistance was supposed to be infinite...   electrons are stored on internal surface area... if they leak through to the other side, they drain out...

Might be a typo, or my misunderstanding? 

PP thoughts only, not a mechanic...

Best regards,

-a-

Resistance check is a quick way to detect dielectric short...ie if using a simple continuity checker...continuity center wire to case =bad cap 

[bob865]

On ‎6‎/‎1‎/‎2019 at 2:07 PM, carusoam said:

Wait a minute...

How did you/they test the capacitor?

Resistance of a capacitor?  Or capacitance?

I thought their resistance was supposed to be infinite...   electrons are stored on internal surface area... if they leak through to the other side, they drain out...

Might be a typo, or my misunderstanding? 

PP thoughts only, not a mechanic...

Best regards,

-a-

If I remember right, you can figure it out by measuring resistance.  It's a completely dead/not completely dead test, not a quality test.  You have to make sure it's discharged first.  It should read realy high, when you first connect the leads and then drop to almost 0.  This high resistance being the volt meter charging the capacitor and then dropping to nearly 0 when it's charged.  I could be backwards or completely wrong.  It's been a while since electronics a-school in Pensacola. 

[Mjknick@gmail.com]

https://www.aircraftmagnetoservice.net/magneto-troubleshooting-guide


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