Cifes 180 control board/PCB?

[PhillipM]

Anyone got any idea where I could find a CIFES 180 Mig control board these days, I'm drawing a blank everywhere.

The connector (bakelite type thing) on it cracked and one of the terminals came out, soldered it back on but when I switch the welder on the main contactor for the transformer closes and the gas valve opens, so I'm guessing that part of the circuit has shorted somewhere but I'll be ******ed if I can spot it on the board.

It's not the torch connections or anything as the wire feed/spot/stitch function still works properly with the torch, so I'm assuming whatever has gone is what killed the terminal/solder joint on the connector (or I've put it back together wrong ), and it's powering/earthing the main contactor/relay.

 

[PhillipM]

A bit of googling reveals a couple of hits under SRL Mig 180, for the same machines, but nothing useful.

 

[mike 109444]

Phil Post up some pics. Might be same as pcb from other machines by different names. A good pic of fault area might allow susing what's wrong

 

[PhillipM]

Yeah, I'll get some shortly, along with the rest of the wiring.

I'm just wondering if I soldered the bloody wire to the right pin now though....

 

[mike 109444]

Quick one would be to unsolder the wire in question and make safe (insulating tape) and then power on to see if it still operaters the contactor ect.

 

[PhillipM]

If I take the wire off the contactor isn't on, but then the torch trigger doesn't work anything

I've attached images of the board and the connector, the white wire in the middle where the crack is is the bit that came unsoldered/broke.
And at the moment, it's basically live all the time, whereas it only should be when the trigger is pulled...

 

[PhillipM]

And the rest of the wiring, the white wire that was repaired is the one on the right in the second picture.

The white and yellow wire on the top of the connector (near the '1' mark), are from the torch, as is the brown wire but it goes via the white housing in the transformer at the bottom (I'm guessing that's the thermal cutout switch)

 

[PhillipM]

Seems to run through the 4N25 chip in the middle there, which is part of the pulse control circuit, anyone know what the resistance from the cathode to the base on one of those should be? I'm wondering if it's shorted from one side to the other, I'm getting around 150 ohms, which I'm not sure is right for an opto-isolater, shouldn't it be damn close to uncoupled?

 

[PhillipM]

...although altering the dial for the spot weld does nothing, so maybe not

 

[Rosepuds]

The wiring to the connector looks ok from looking at the photos. The white and blue wire on pins 4 and 5 on the connector are the supply for the PCB. The contactor goes to pin 9. I would say the PCB is faulty from what you describe. The connector is driven by the triac on the PCB. It could be this that has failed or it could be components that control the triac. I repair PCB`s from welding equipment and can test and repair it for you if you would like.

 

[PhillipM]

Depends what you think it would cost?

I'm half tempted to just grab some breadboard and replicate it.

 

[PhillipM]

Okay, I see what you mean now, that pin is driven by the 206D triac, which comes of some of the amplifiers and the 4N25 chip from the timer circuit, I think the chip must be okay as if I disconnect the black wire the wire feed and timer work fine, so it may well be just the triac, with a bit of luck....

 

[PhillipM]

Right, i desoldered the ground pin from the triac to see if it was that which had shorted - tried the welder, and no contactor....so I'm guessing that's fine?

 

[PhillipM]

Traced it back through the transistors, etc, they check out okay, all the way back to that 4N25 chip again....and if I desolder pin 1, which is the supply to the diode to turn it on, it still switches on, worth a shot for 45 pence of chip...

With a bit of luck, it'll sort it out, and I can crack on with treating it to a nice capacitor bank and a 180mm fan to replace the rattly old thing on there atm...

 

[PhillipM]

45 pence later, one working welder, bingo

Also got rid of the slight hesitation it had before starting the arc sometimes, must have been a bit flaky for a while.