sip migmate dp intermittent working

[kingkay]

Hello all,
Yet another new bod with yet another sip problem. Read lots of other issues with them on this forum but not come accross this yet.

Sometimes it all works suprisingly well on all powers and for a reasonable time.

Other times from cold the fan runs and nothing elese happens. Not related to it being hot, and not a loose connection that I can find (checked with multimeter) The feed motors not getting power, nor the torch. 240v going into pcb but thats as far as it seems to get. I guessing the relay isn't switching - if I bridge it out I get power to the torch tip but not to the wire feed?

The wiring diagram I've come accross for this model doesnt match the pcb in my welder as it shows 2 wire into cn3, 2 wires into cn2, and four wires into cn1. Where as I'vegot nothing connected to cn3, 3 wires in cn2, 4 wire incn1

Any ideas much appreciated (I'm saving up for something better).

thanks

Toby

 

[voipio]

It's worth having a good close look at the wiring and PCB for dry joints. Make sure the switch contacts make properly every time, too.

 

[kingkay]

Hi voipio thanks for the reply. Ive been mucking about with it again today and still no joy. If I close the relay with an insulated screwdriver the feed motor now works (not sure why it didnt before), the pcb transformer is giving out 25v so that looks ok but still no power into the relay and not sure what to do next. checked continuity along all wires and joints. Whats the 3 legged thing attatched to the heat sink and what does it do? - a new board will fix it I'm sure, but they seem to be about 70 quid. I'd rather put the money towards something a bit better - but in the mean time ive got to get something welded up asap.

thanks
toby.