Sewing machine Guru needed ;)
Elna Grasshopper (new to me) circa 1950
The light works, but there was no hummm when knee pedal engaged.
I have the motor out, and it is very stiff to turn. I'm...
I just purchased a fairly tidy Elna 'Grasshopper' sewing machine (1951) with the same leaking capacitor problem. I carefully removed the capacitor for examination. It is actually three capacitors in one - no chance of a direct modern replacement, but anyone with those three capacitors, a couple bits of insulated wire, and a small soldering iron should be able to shoehorn them into the same space. There is a circuit diagram printed on the side of the original capacitor, showing one 0,2 micro-Farad capacitor between the two mains power buses (the two wires from the top of the original capacitor which are soldered to the top of the two outer brass bars where all the wires attach), and following on from each of those a 0,0025 micro-Farad capacitor (so, two of those), the other side of both of those joined together and going to the chassis - representing the one cable from bottom of the original capacitor, which is screwed down. Easier than it sounds - I just have to find those capacitors. They must be NON-polarised capacitors, rated for 250 Volts, and I plan to use radial (rather than axial) style, aluminium type ones - very common. From what I can gather, I believe they are needed for that lovely little motor to run properly - to have torque ('oomph') at start-up.
As to the motor not wanting to turn... difficult to say from a distance. Could it be that the 'brushes' are sticking - or even worn out? There are two, top and bottom, that ride on the commutator - the ring of bronze-colored squares on one end of the motor, behind the wiring. They are made of carbon, are what power the motor, and are held with hidden springs. With much use they wear down, but I would not expect them to be completely gone. The upper one is easiest to reach - there is a brass screw above it - careful the spring doesn't get away. Only other thing would be fouling of the bushings that allow the axis of the motor to turn. A little penetrating oil could help there. The motor should turn very freely.
May 16, 2011 |