OK, this is a long shot. I got this sewing machine cheap because it's end of line, ex-display, and had no pedal. The genuine pedal costs £60, while Ebay knock-offs go for around £15. So I went for the knock-off, it doesn't work, and I'm not sure whether it's the pedal or the sewing machine that has the problem.
Now this is an electronic machine, unlike the old fashioned sort where the pedal was a big resistor in series with the power to the motor. Here, the pedal is just (I think) a variable resistor fed with a 5 volt supply, and limited to a current of 5 milliamps. Assuming that the sewing machine is working.
Turning to the pedal. This connects to the sewing machine via a small connector the size of an MP3 player headphone jack, but with just two connections. Internally it is a 200 ohm resistor in series with a sliding linear potentiometer. Unpressed it shows a resistance of c 25k, and this drops linearly when pressed to 200. The sewing machine does not respond to it. The pedal does however contain a trim pot, enabling the maximum resistance to be increased to about 45k, and when adjusted to that maximum the sewing amchine starts up straight away (at about half speed) with the pedal unpressed, then stops when it is pressed. I've tried to jerry rig random resistors, but had no success at getting anything to work.
Does anyone have any ideas for what else I could try. It would be wonderful if someone had this exact model of sewing machine and could check the pedal resistances for me, but that is a very long shot. Of course that is assuming that the pedal works by resistance and not through some overcomplex active circuitry. Any suggestions would be gratefully received.
Now this is an electronic machine, unlike the old fashioned sort where the pedal was a big resistor in series with the power to the motor. Here, the pedal is just (I think) a variable resistor fed with a 5 volt supply, and limited to a current of 5 milliamps. Assuming that the sewing machine is working.
Turning to the pedal. This connects to the sewing machine via a small connector the size of an MP3 player headphone jack, but with just two connections. Internally it is a 200 ohm resistor in series with a sliding linear potentiometer. Unpressed it shows a resistance of c 25k, and this drops linearly when pressed to 200. The sewing machine does not respond to it. The pedal does however contain a trim pot, enabling the maximum resistance to be increased to about 45k, and when adjusted to that maximum the sewing amchine starts up straight away (at about half speed) with the pedal unpressed, then stops when it is pressed. I've tried to jerry rig random resistors, but had no success at getting anything to work.
Does anyone have any ideas for what else I could try. It would be wonderful if someone had this exact model of sewing machine and could check the pedal resistances for me, but that is a very long shot. Of course that is assuming that the pedal works by resistance and not through some overcomplex active circuitry. Any suggestions would be gratefully received.
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