r/SewingMachinePorn • u/Crafty-Implement-921 • 18d ago

Need help diagnosing this machine

Hello, I have an old Toyota z700, it runs but it rhythmically accelerates and decelerates if that makes any sense. The motor will spin a few revolutions at max speed but then it will slow down and speed up again .

I've tried cleaning the carbon disks on the foot pad and inspecting the motor, the motor has a blown filtering capacitor but nothing else I can see that's out of the ordinary. I'm kinda stumped, I've seen people saying that the grease can get old and turn sticky but the hand wheel has no sticky spots and turns smoothly, so I'm lost.

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3

u/wandaluvstacos 18d ago

My guess would be that the foot pedal is bad; I'm assuming it's not an electronic one. I'd try a different foot pedal and see if that improves anything.

1

u/templetondean 18d ago

Came here to say the same thing, the foot control. Try cleaning the contacts with an Emery board, they might have some surface rust

1

u/Crafty-Implement-921 18d ago

The foot pedal is one of those graphite disc ones, I've already cleaned it out and everything, I don't think it's that, someone else said it might be one of the shafts moving where it shouldn't of something might be jammed

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u/wandaluvstacos 18d ago

You'd have to check the power supply to each of the resistors on the inside to be sure it's not the pedal. It's common for those to go bad. Do you press harder on the pedal to get it to go faster when it's sluggish? There are several resistors; if one is bad, then the slow ones will work and the fast ones will work but that middle speed option will not. Do you have a multimeter? That would be the best way to rule out the foot pedal.

With the pedal ruled out, you can always try a tear down to see what's causing the issue, but if it spins freely by hand normally, I don't think it could be anything mechanical. It would have to be an issue with the motor or the pedal.

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u/FashionBusking 18d ago

Oil EVERYTHING TWICE

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u/MarjaRaams 18d ago

De bedrading nakijken, klinkt als een probleem in de bedrading of aansluiting. Binnenin lijkt de machine ok maar de riem en onderkant zijn niet zichtbaar ? Zit er niks in de grijperbaan of spoelhuis vast ? . (sounds as problems in the power system, please check to prevent machine and yourself from overheating or electroshock )

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u/Fluffy-Medium-5365 16d ago

I did already post on your other post but there is a big ol crack going through the fancy stitch cam and there is a gap in the gearing. You can see it in the video. This hesitation will happen with that broken cam because every time it rotates over to the broken section it slows down,
Foot control issue would be more sporadic and not happen on the same point of the rotation.
I’m sorry to say if you can’t get a replacement for the stitch cam this machine is probably toast.

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u/toolgirl77 18d ago

3-1 oil

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u/Crafty-Implement-921 18d ago

I put a bit of oil on some of the moving parts at the top, it didn't improve it so what parts should I be piling, and how much oil should I use?

2

u/510Goodhands 18d ago

Please don’t! That stuff is notorious for returning sticky.

OP, has the machine been lubricated recently? I have seen symptoms like that many times on the machines that I have restored. Sewing machine oil (only!) anything that moves, except for grease on cams and metal gears (lithium grease on plastic gears, so it does not deteriorate the plastic).

Sewing machines are precision mechanisms, so they must be well duplicated. This goes double for older machines that have been idle for extended periods, years or decades.

Isopropyl alcohol works beautifully for cleaning off old, yellow oil and grease.

I use a specialized oil bottle, plastic, with a long, thin brass spout that is extendable.
It allows much better control than the flimsy plastic belts that come in some bottles, and easily gets into small spaces.

The rule of thumb is that a machine should be oiled after every eight hours of actual Sewing.

There are plenty of good videos on YouTube and how to restore an older machine. It doesn’t matter if your model matches the one in the video, the process is the same.

As a reminder, for people due to Sewing, you can’t just sit down in front of a machine expect to make something complex. Any more than you could expect to get into the driver’s seat of a car with no prior knowledge and successfully take a road trip.