I tested both of the above and the torch switch wiring before i did anything else, that fuse on the aux trans seems to be the only one in the machine, and i tried bypassing the thermal switch on the rec completely, it has to be something on the board, power is getting to it, torch switch worksYou can also check continuity of thermal switch that's fitted on rectifier
Theres no shorts in them at least, probing at them in circuit, Would one of those going faulty also stop the board sending power to the coil of that green relay? i'd assumed they'd only have an affect on the wire feed sideTest the two big transistors. One is for drive the motor. The other is for the brake.
Hello eddie and thanks as always, the meter reads roughly 300mv dc with the switch connectors open, but unstable/decreasing, but nothing for current when i bridge the meter across them as far as i can tell, the spot switch timer pots wake the relay/contactor up when switched on but appear to be opperating normally probing them, the two pins i think are the switch are conducting when clicked off, so i can only assume by switching them on its diverting power away from the problem and making the relay work but still no power getting to the feed motor.As you said, the initial fault to investigate is why the small green relay is not being activated when the torch trigger switch is closed.
I think the trigger wires enter the board at push-on tags 3 and 4. You need to follow the PCB tracks from there, tracing out the circuit as you go. This is done by turning the board over and back, looking at the component- and non-component sides, whilst sketching a diagram. From the photos, it looks like NPN transistor U23, BC546, may be involved.
With the trigger switch open, i.e. tags 3 and 4 ( assuming those are the correct numbers ) not wired together, what is the voltage across those two tags?
If you join tags 3 and 4 together with a meter set to DC milliamps, what is the current indicated?
Check that the on/off switches on the back of the Spot/Stitch timer pots are conducting when Off. Does altering these two controls make any difference to the fault?
As well as Tec-Arc:
this company also offers the same PCB repair service, apparently at a lower price:ESAB COMPACT MIG WELDER W22E, W26E CONTROL PCB REPAIR SERVICE | eBay
W22E OR W26E. MIG WELDER PCB REPAIR SERVICE. We can repair PCB`s out of most makes and models of welding machines and plasma cutter, including inverter welding machines. TEC ARC is a leading manufacturer and repair centre of arc welding machines.www.ebay.co.uk
emimattl.com - emimattl Resources and Information.
emimattl.com is your first and best source for all of the information you’re looking for. From general topics to more of what you would expect to find here, emimattl.com has it all. We hope you find what you are searching for!www.emimattl.com
Out of curiosity i desoldered v24 to test it, bc372s is supposed to be a darlington from what i can tell, my tc1 meter reads it as a thyristor for some reason, this tester is supposed to identify a darlington so maybe this is also a problem?You can use the same type BC-546 for V24. In the beginning they use a BC-373 but later the BC-546.
The very high gain of a Darlington pair, where the first transistor amplifies the base current into the second transistor, causes a rapid rise in collector current. This may be so fast that your Multifunction Component Tester thinks it is dealing with a switch, and so classifies the device as a thyristor.Out of curiosity i desoldered v24 to test it, bc372s is supposed to be a darlington from what i can tell, my tc1 meter reads it as a thyristor for some reason, this tester is supposed to identify a darlington so maybe this is also a problem?