Migmate 100 wire feed

[Foden man]

Happy Christmas everyone and thanks for allowing me to join.
I have a Sip Migmate 100 that has been in dry storage in the back of the pantry for the last 25 years and have just pulled it out as need to put into use.
The problem I have is that the wire feed motor, although on occasions will vibrate when the trigger is squeezed, I cannot get it to rotate properly. It has done the odd little slight movement, but very slowly and only around half a turn.
I've removed the 24V wiper type motor and powers up fine from my Power probe off a 12V battery.
I've sprayed contact cleaner as best I can on the wire feed rotational switch and checked the contact inside the trigger on the torch.
The machine buzzes when the trigger is pressed and that is what can sometimes me felt through the motor.
When the motor does turn a tiny amount it feels juddery.
This machine is almost mint and far too clean to write off.
Your help and guidance would very much be appreciated.
Thanks.

 

[Dapph2]

Sounds like your wire is rusty or the feed tube for it is dry . Did you pull 2 mtrs of wire through the nozzle with pliers whilst operating the trigger ? Do the feed rollers turn by hand or when driven if the clamp is not clamping the wire ?

 

[eddie49]

Hello and welcome to the Forum.

The early SIP Migmate machines are quite sought-after, but more as antiques than as welders!
When installed in the welder, that motor gets power from the main DC welding output, which is often low or missing due to poor contact at the totally inappropriate pushbutton power selection switches. They would be OK for the waveband selectors on a 1950s valve radiogram, or the controls of a reel-to-reel tape recorder, but are completely wrong for a welder. Even without feeding wire, can you strike a good arc from the end of the wire in the MIG torch to a piece of scrap metal held in the workpiece clamp? If not, it means the welding output voltage is low, and this is also the reason for the motor not running correctly. That voltage, from torch to clamp, should vary from about 15v to 30v DC, depending on the setting of those switches. As an initial solution, try cleaning the switches by spraying them with contact cleaner and operating them repeatedly.
If the DC voltages are correct, an alternative reason the the wirefeed problem could be dried-out, solidified grease in the motor gearbox.

 

[bricol]

If I recall correctly, intermittant issues with my Migmate wire drive motor were due to oxidised connections inside the machine where the motor power was taken from. Cleaning and remaking them sorted it

 

[DaveB]

You've not said whether the wire feed motor is giving problems with the wire in place.

Turn the wire feed to maximum and with the wire removed and the tensioner off pull the trigger.
If the motor turns fast then the problem is elsewhere.
If teh motor is slow and juddery but the welding volts are good then the preset pot on the motor control board might need a turn or two backwards and forwards to wipe the track clean.

 

[Foden man]

Thanks for the replies. The wire feed motor is out of the machine and only attached by the two wires, no load on it at all.
It runs fine when tried on a 12 volt battery, but have done that with it out of the machine.
I haven't tried the welder with mig wire sticking out of the torch to see if it will actually arc
I have used contact cleaner on the rheostat and on the power selector buttons and worked those a lot.
I can't find any evidence of green terminals or burning anywhere.

Trying it today, with power and wire feed on the highest setting, I can turn the roller with my fingers and help it around, but as soon as I stop, it stops.
I was wondering if there's some sort of capacitor that isn't allowing enough power through?
Thanks again for your replies. I'll check for an actual spark tomorrow