Removing capacitors
 

Some SM's have capacitors in the motors and some have them in the foot controllers. In some cases people have said it's ok to remove them and do nothing else. I've heard others say they should be replaced. Originally they were to avoid creating static on tv's and radios through interference.

At some time Bernina foot controls had problems and repair places removed the capacitor and maked the pedals once they were removed.

I have heard stories of them going bad and machines that run on and on without stopping, even overheating and causing fires. I haven't personally had that experience..

Recently I found a nasty gooey oozing capacitor in my Elna grasshopper motor area and completely removed it. The machine runs just fine.

Now I am working on my Pfaff 332 and when I look in motor compartment I find TWO capacitors. **It's hard to tell but I think they are ok? The ends of them are strange to begin with ...sorta like melted plastic with wires jammed in. I sorta would like to remove them as long as I'm in the area but I'm not sure if that's ok. And then if it is...remove one or both?

I'd love to get advice from someone else iwth a Pfaff who's "been there", but would also like to hear some discussion on capacitors in general.

Capacitors are used for a variety of reasons. In some cases, as you mention, they are to shunt noise so that electromagnetic interference is lowered (that's the static on the TV thing). Motors in particular generate a lot of electrical noise, so capacitors help reduce this.

They are also used to keep the power level uniform - think of them as little springs or batteries that work 2 ways, like an energy bladder - too much energy they store up the excess, too little and they give stored energy back to the system.

While something may work with them removed, it won't be as originally designed, and more importantly tested for proper operation and longevity, as well as "playing nice with others".

What your describing as "melted plastic" is kind of exactly that - it's the potting compound used to keep the wires going to the innards of the capacitor separated (so they don't short out - one goes to power and the other to reference) and provide mechanical stability as well.

Michelle
(retired electrical engineer)

Awesome post.

One add: Bottom line, you should replace them. or replace the pedal entirely.

Thank you Michelle. That's good input!

Steve, I see what you're saying but then WHY did Bernina just remove them from the 830 pedals and not replace them?

lazy is not a new thing....
folks who think that they know more than the design engineers....
ignorance....
boss told them to.


take your pick, hehe

Mechanics and engineers don't always see eye to eye. Lots of knowledge on both sides. I have no opinion on this instance but I worked in the building industry and it seems the carpenters and architects were frequently in disagreement.

Jon

Bernina did not recommend just removing them from the foot controls. Idon't know where this is coming from? They came out with a retrofit part for the foot controls once the capacitor was removed. If your foot control does not have the thermo regulator part, it's not operating as it should.

OK I've obviously heard wrong on that. Pardon me. I agree it could easily be that I am incorrect.

Still the point is that I have read meny people simply removing capacitors and saying it is not needed to replace them.

If they are meant to balance out the energy...isn't modern day electricity delivered in a more evenly balanced fashion? Are they still needed? Are RC cars and other things with similar motors wired with capacitors for noise suppression?

I am only asking questions here to learn so please understand I am not trying to be deliberately argumentative.

Your question is a good one. I didn't like the way this was turning into a Bernina bashing thread, lol. Bernina still warranties these foot controls 30 years later and replaces the faulty capacitor with the thermo regulator at no charge to the consumer. I don't know of many or any sewing machine manufacturers that would do this for their customers. :>

In theory modern power is more stable at the source, but we have FAR more things downstream between source and you that can effect power stability. (here at work each of my critical servers are behind a device called a power conditioner. it is essentially a $1000 set of capacitors and circuits)

ALL modern appliances from phones, to blenders, to cars have capacitors in the circuits for power management.

Noise suppression, power stability, circuit protection, etc. MANY uses.

You do not seem to me to be argumentative, seems to me that you are being inquisitive.