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Old 26th Apr 2019, 5:15 am   #1
Kris_carnage
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Default Vintage sewing machine suppressor help!

Hi.

I bought a vintage Singer 401 (i think) sewing machine for cheap as this came without foot controller. However I happened to have a modern one which I had got to fit my vintage Singer 99k.

I used the foot controller at the seller's house with no issues, so I purchased the machine. I brought it home and cleaned and oiled it up. I put the foot controller back in to try out the machine, and the machine was really struggling to go. It then went pop and a puff of smoke near the motor. I took it apart and it looks like the Interference Suppressor has gone on it. I thought oh that's fine I will pop down to the electrical shop and see if they have a replacement, but I was soon told this part is not a thing they have, nor did they have an equivalent part, nor make anything like this...

Now I am not electrically minded AT ALL, so I am really struggling to find any information on this part, whether I can buy a part like this or even any kind of equivalent thing that will do the same job.

I would love to be able to get this sewing machine going again, so any information on if it's fixable would be greatly appreciated! However there will be a cost where it would just not be feasible.

I have attached photos of the part, which I hope will help.

Thank you immensely.
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Old 26th Apr 2019, 9:53 am   #2
paulsherwin
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Default Re: Vintage sewing machine suppressor help!

It's difficult to know how to advise you given your lack of electrical expertise. Your interference suppressor is just a capacitor and two inductors in a plastic case, and one of the inductors has probably burnt out. You can operate the pedal with the suppressor removed but this can be dangerous if you don't know what you're doing. I'm not familiar with suppressors inside the machine body - the 99K has an external motor and any suppression is inside the pedal.

There is also the question of why the suppressor has failed. It may just be age, but it's more likely that the motor or its associated wiring has a fault which is causing it to draw excess current. Does the pedal still work with the 99K?

If you still have an old fashioned sewing machine shop in Hamilton you could ask for advice there.
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Old 26th Apr 2019, 10:10 am   #3
Kris_carnage
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Default Re: Vintage sewing machine suppressor help!

Thank you for your response.
Last time I used the foot it worked on the 99k, however I have not used it since a new wall plug was added to it.
This is something I can double check in the morning, no worries.
If suppression happens in the foot for the 99k, could this likely work for the 401 too? Or could it be possible that the modern day foot has caused this to blow?
Is it likely I am risking anything (safety wise) by using a modern day foot on the 99k? The machine had terrible control with a knee bar. I have an RCD in use also. I have used a modern day foot on an old Packard machine with no issues as of yet, however it is still early days.
I will see if I can find someone locally that deals with repairing vintage machines and see what they might say on the subject too.
Thank you
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Old 26th Apr 2019, 12:00 pm   #4
paulsherwin
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Default Re: Vintage sewing machine suppressor help!

A modern control pedal uses a thyristor and other electronics to control the motor and will be fine with a 99 or other machine with an external motor of a similar type. There are no safety issues, though the fact that the metalwork isn't earthed is less than ideal regardless of the controller used. It's possible that the interference suppressor inside your 401 wasn't happy with the electronic controller.

The original pedals supplied with these machines were completely passive - just a rheostat (variable resistor) and a couple of suppressor capacitors.
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Old 26th Apr 2019, 1:10 pm   #5
David G4EBT
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Default Re: Vintage sewing machine suppressor help!

The suppressor you have consists of a capacitor and two RF chockes.

With age, the capacitor can (& do) go short circuit, often with an alarming bang. The role of the suppressor is to prevent the motor causing interference to radios and other audio equipment. Any mains powered motorised equipment such as a vaccum cleaner, electric power tools such as drills, sanders, routers etc, will have a suppressor, but usually only an Class X capacitor.

My only experience of sewing machine motors is when I used one with a foot controller in a Coil Winder I designed and made. It worked a treat till there was an almighty bang in the controller and I had to check that my foot was still intact. The foot controller was decades old, and the 'suppressor' was just a wax paper capacitor - not a Class X one. I replaced it with a Class X one and it's worked fine ever since.

You'd probably be fine with just a Class X capacitor, (which is what would have been fitted to more modern sewing machines), though 'vintage' suppressors such as yours, like the one at this link, are available on eBay. Described as 'tested and working' but by virtue of its age, it's anyone's guess for how long. That said, it's not a big outlay and international post is reasonable too:

https://www.ebay.co.uk/itm/352295172180?rmvSB=true

I've attached a quick sketch of the circuit of your suppressor as it most likely is, and the alternative option with just a Class X capacitor.

Hope that helps a bit.
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Old 26th Apr 2019, 1:24 pm   #6
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Default Re: Vintage sewing machine suppressor help!

The symptoms described don't tally with a failed capacitor though. If the capacitor failed, it would smoke and go bang, but the motor would continue to work. If the motor is now dead then something has broken the circuit, probably one of the chokes.

As I mentioned in #2, it should be possible to simply remove the suppressor and wire the motor directly to the controller socket, but I am reluctant to recommend this to someone with no electrical knowledge. It's an easy modification to make, but a wiring error could make the metalwork live.
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Old 26th Apr 2019, 1:44 pm   #7
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Default Re: Vintage sewing machine suppressor help!

Interference suppressors (like the old one in the OP) are also known as line filters, perhaps something like one of those shown in the data-sheet below would be suitable, we just need to figure out the type (the current rating of the original is 1A).

http://www.farnell.com/datasheets/1842668.pdf

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Old 26th Apr 2019, 1:53 pm   #8
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Default Re: Vintage sewing machine suppressor help!

That metal cased unit is for an earthed circuit.
The machine has a 2-core mains lead.
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Old 26th Apr 2019, 3:14 pm   #9
paulsherwin
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Default Re: Vintage sewing machine suppressor help!

The standard Singer controller connector used until the mid 60s only has 3 connections - neutral, live (for the sewing light) and controlled live (for the motor). There is no provision for earthing the metalwork. I always use mine with a plug in 30mA RCD and take care not to be in contact with anything earthed.
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Old 26th Apr 2019, 3:38 pm   #10
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Default Re: Vintage sewing machine suppressor help!

My late mother had a Singer sewing machine with that 3 pin connector (I have it now). I repaired it a few times, and I think it pretty much meets the requirements for double insulation (and thus the lack of earth is not a major problem) :

The motor is encased in a (bakelite-like) plastic housing, which also holds the ball races. Thus the motor and spindle are insulated from the machine body. The motor spindle has a metal worm gear on the end which meshes with a fibre (insulating) gear on the back of the handwheel. Note that the spindle/worm can only be reached by removing covers with a screwdriver.

The lamp/switch is a solid bakelite-like moulding.

All internal wiring is sheathed, so I think that's double-insulated too.
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Old 26th Apr 2019, 4:34 pm   #11
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Default Re: Vintage sewing machine suppressor help!

I have a 99k, it's mainly a display item but I keep it threaded and do occasionally use it.

The last time was to hem some curtains for the grandkids Wendy house in the garden. When I came back into the house from hanging them, the 99k was going full pelt stitching its own thread together!
The suppressor capacitor was nothing special, and was across the rheostat in the foot-pedal and had gone short circuit in the half hour or so when I was absent.

Moral of the story, don't leave vintage stuff plugged in unattended.
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Old 26th Apr 2019, 5:43 pm   #12
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Default Re: Vintage sewing machine suppressor help!

I had a similar thing happen to my wife's machine. She was sewing when it suddenly went full tilt. The capacitor inside the foot pedal had failed short circuit. Not the best thing to happen. It appears this may be a common failure. I'm pretty sure I had a fault in an industrial food mixer that we got second hand and it had a similar thing happen. This time just lots of smoke from inside the machine and the motor stopped. I think it had a thyristor controller which luckily survived apart from the capacitor.
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Old 26th Apr 2019, 5:51 pm   #13
paulsherwin
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Default Re: Vintage sewing machine suppressor help!

Very common fault with old sewing machine controllers. My 1934 201K did exactly this. I now always recommend that people change the suppressor caps in any rheostat based controller rather than waiting for them to fail. Of course, you shouldn't leave sewing machines unattended with power connected, but inevitably you sometimes forget and come back to find it running full pelt.
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Old 26th Apr 2019, 10:16 pm   #14
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Default Re: Vintage sewing machine suppressor help!

Paul, am I correct in thinking the new pedals work like a modern light dimmer?
If so, that's the reason for the suppressor failing, modern dimmer type contraptions don't put out 50 Hz all the time, only on full power or off, the said component is expecting 50 Hz, not something heading towards 1 kHz and beyond.
It does seem unusual to have the suppressor in the machine itself, it's usually an elcap (or any other brand) fitted across the pedal terminals.
Don't worry Paul, I changed it to an x type before 'that' cap did anything untoward.
Take note, it says 'that' cap, I treat all PIO's as grid decouplers, replace on sight, preventative maintenance I suppose.
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Old 26th Apr 2019, 10:29 pm   #15
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Default Re: Vintage sewing machine suppressor help!

Yes, one possibility is that the controller is interacting with the suppressor with disastrous results. If it were my machine I would simply remove the suppressor but I'm not sure the OP can do that correctly and safely.
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Old 26th Apr 2019, 10:53 pm   #16
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Default Re: Vintage sewing machine suppressor help!

Removing it is one option but there may be strict rules in New Zealand regarding RF suppression.
I don't know what the rules are over there but the rules here are a bit 'hit and miss' unless someone can clear up the suppression laws.
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Old 27th Apr 2019, 11:53 am   #17
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Default Re: Vintage sewing machine suppressor help!

A replacement from the white goods bins would probably cover law suppression requirements such as this.

https://www.ebay.co.uk/itm/HOOVER-vh...AAAOSw~2hbyLye

But like David have used an X type capacitor without any further drama on a 1970s Singer foot pedal that did exactly the same thing after a length of storage.
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Old 27th Apr 2019, 12:48 pm   #18
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Default Re: Vintage sewing machine suppressor help!

The controller pedal will have its own interference suppression anyway. Machines with an external motor never have any suppression on the motor itself.
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Old 27th Apr 2019, 3:02 pm   #19
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Default Re: Vintage sewing machine suppressor help!

That's what I thought, the OP's motor is unusual, with it having it's own suppressor and all that.
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Old 8th Sep 2019, 10:26 am   #20
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Default Re: Vintage sewing machine suppressor help!

I've just bought a vintage Sew -Tric motor and after connecting to mains I heard a bang. I attach a picture showing the suppressor. I need to replace this as it's reading 18K when it ought to much higher. Original suppressor made by Dubilier, part "SPM 669". Will replace with a brand new suppressor when I identify one. I see that there are no RFC's in this, just 3 capacitors. That metal round bit you see has (I'm assuming) to go to chassis, which it does as it's pressed into the compartment made for it. Also printed on suppressor is "0.025uF + 2x .0025uF". So, I'm looking for something similar.
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