Cooked 66K electronics
 

I picked up a decent 66K for a song the other day, owner said it didn't run. It's a knee operated motor, with a pair of capacitors clamped to the chassis below the flywheel. Motor runs like new, but one of the caps is clearly cooked, there is a heap of goo below it.
Are these caps jut rf suppressors like in many foot controls? Can I snip them out of the circuit, or do they have other functions?

I would remove them intact if you can. They should just be attached to the wiring by screws.

RF suppression is why I have read they were there. Although I've never seen a 66 with any on it.

Joe

My 99K had them, a bit like two small size AA batteries. When I had my machine rewired they just removed them. Apparently we don't need them today, radios and TVs aren't affected by the sewing machine like they used to be. It has nothing to do with the function of the motor or the running of the electrical parts in themseves. Maybe if you listen to a very old radio with tubes while you sew it might interfere with the signal a bit;- )

I took them out, and it runs perfectly. This is the third machine in a short period of time that I've had to do this with. Pfaff 360 (cap in pedal), Elna Supermatic (cap in machine next to motor) and now this one. These where like two AA batteries like Mickey described them, clamped to the motor bracket with the bracket bolt. This one is a knee lever model. The cap is sitting in the foot pedal in most Singer models, I think.

Are those some kind of thing people added onto a machine? I don't think I've ever seen that. Pics?

Miriam this was a lot more common in other countries than it was here. Have no idea why though.

Cari

I screwed them back on just for you, Miriam. You can see the stuff that dripped out of the cooked capacitor below, just like splats from a candle. Easy to spot.
The other image is the foot control for a Necchi Supernova. Same symptoms, start running on its own, no control over speed, etc. Reason not so apparent when the culprit is hidden. The cap is gone, you can barely see the stumps of the leads near the screw terminals, plus remnants of the mess from the cap.
Yeah, I forgot to mention the Supernova in the last post - that's 4 machines that needed surgery - electomies?- of the 8 I bought over the last couple of months.
I opened up the 201K pedal, there was no cap in there, I was wrong about that.

Miriam,

Here's the capacitor in my Elaine's 319K.


[ATTACH=CONFIG]534901[/ATTACH]

Joe

On a higher AC voltage power supply (all of Europe, UK, Australia, New Zealand etc. actually most of the world) the capacitors prevent sparking from the motor brushes and suppressed AM radio interference. They're not required: I always remove them and throw them away.
The one time I didn't (because they seemed okay) they failed a day after I handed the machine back (it was a service). Taught me a good lesson.

I'd go with the surgeons here: If in doubt, cut it out.

Joe, is Elaine's machine still 220-240V? I'd remove that capacitor, but up to you. When it fails it'll just short circuit and the motor will go to full speed all the time

Mike,
Elaine's 319 is a US model running standard 110-120 volt current. I thought about taking it out, but it's never malfunctioned so I left it. I might regret that, but if so I'll fix it.

Joe