cp welder repair

[cowmechanic]

Hello all . I have been dipping in and out of this forum for awhile ever since some members helped trouble shoot my sip ideal 240. Anyway a friend of mine has a CP 250 mig welder ,It appears to be italian made and looks in good condition internally and cosmetically however it wont work. There are two pcbs. one is mounted on a small transformer and has 2 glass fuses that are intact and an led which glows when the machine is turned on.the other pcb is behind the front plate and houses a digital display and the wire feed speed control. When the machine is turned on ant the tigger pulled the contactor works and the main transformer hums but the wire feed motor doesnt operate and i dont think the gas solenoid works either any ideas on where to start investigating appreciated.

 

[mike 109444]

Hi CM the small transformer is probable supplying the low voltage to the pcb and maybe something else hence 2 fuses. There will probable be 2 wires going IN to the small transformer these will be the 240v. Then there will be 3 or 4 wires coming out via the fuses, 3 if it is sharing a common or 4 if it is using a separate common for the 2 voltages. Pic of pcb might allow pointing to areas on pcs to check and or replace.

 

[mike 109444]

Try metering the output(s) of the small transformer using the pic below for a guide note voltages will be AC around this part Take care as mains will be present.

 

[cowmechanic]

hopefully get a look and few pic of the machine at the wk end

 

[Welderfix UK]

Yes, as Mike says you need to eliminate that small transformer. The output of this usually runs a relay which powers the motor drive to the wire feed. Be careful though, as mentioned there is mains on the primary.

 

[cowmechanic]

Back at machine today. It is a awelco sp 3001 .The small service transformer is getting 240 volts but is not supplying any current as far as I can see The led is illuminating on the pcb on the transformer .It appears that the cooling fan should be getting 240 volts from this pcb but is not . there are an additional 6 wires that supply the wire feed motor and gas solenoid etc and they have no voltage either.I will try and post a few pics.

 

[cowmechanic]

Pictures ?

 

[mike 109444]

The pics are very blurry. From what you describe ref the fan not running this might be correct in that the fan may only run when the temp of the welder gets to a certain point. Again the circuit diagram pic is to blurry to be sure.
If you are getting 240v on the spade connectors on that pcb, which seeing as the led is lit I would think is the case. Then you could be looking at a fault with the relay (the black box on pcb) or what looks like a thermister (the blue disc on pcb) but that may just be a capacitor and nowt to do with fault.
Is there a transistor mounted under the pcb between it and the metal plate its mounted to? (bottom left of the pic)

 

[cowmechanic]

I'll try and get better picture tomorrow

 

[mad murph]

I'll try and get better picture tomorrow

hi was just wondering what was wrong with the welder . i have the same problem with my sp3001 i got the relay replaced but the welder still dosn't work any ideas thanks.

 

[mike 109444]

hi was just wondering what was wrong with the welder . i have the same problem with my sp3001 i got the relay replaced but the welder still dosn't work any ideas thanks.

That's the problem you can't be sure if it's been fixed or the person is lead out in there shed having touch the wrong bit
Do you have the same diagram ?
Can you scan it and post up as that would help with the diagnoses. Having looked again at CM's pic of the transformer it looks like the pcb on top of it produces some of the logic voltages for the digi display so would have 5 and 12 VDC going off to the display pcb. So you would need to meter for AC and DC voltages.
What does and does not work on yours?
And Welcome BTW MM

 

[mad murph]

hi, was in mid weld and it just stoped the only thing that works wen you squeese the trigger is the gas. the red light is working on the same pc board as in the other pic the second pc board is also lighting up with the number display. the contactor is working. there only is the 1 relay on the first board and i got it changed but still not working any ideas. thanks

 

[mike 109444]

Not sure if you are trying to sort this machine (i've been stuck with hotel internet connection all week, gave up!) If you meter between the earth clamp and the welding tip (remove shroud to make it easier) Set meter to DC volts and when you pull trigger you should see between 15 to 30 volts. If you do then that is another part that is still working! and it is then only the wire feed motor that's not. Might be the supply to that that's at fault.

 

[mad murph]

took shrude of and pull trigger put tip onto earth and it sparked so the power is goin to there ok but wire not working. there are 2 pc boards on this welder 1 with the 2 fuses like the pic you have and the other is the 1 with the wire speed nob on it is it the 1 that supplies the wire feed motor ?????

 

[mike 109444]

Well that's one way to test it! Does the fan work?
The only info I have is what was posted by CM and the image of the transformer mounted pcb and the circuit diagram are both so poor that it's impossible to use for diags.
It looks like the transformer pcb is mounted to the transformer by it's wires being soldered through the pcb. So there should be 240v AC on one side and one or more lower AC voltages on the other. Do you have the diagram that CM posted up earlier in the post?
The little I can make out from the diagram indicates that the motor is feed from the one with the wire feed knob (which would make sense). If you don't have the diagram then try and take some decent pics of both pcb's inc underside of pcb with the knob on.

 

[mike 109444]

That's the problem you can't be sure if it's been fixed or the person is lead out in there shed having touch the wrong bit
Do you have the same diagram ?
Can you scan it and post up as that would help with the diagnoses. Having looked again at CM's pic of the transformer it looks like the pcb on top of it produces some of the logic voltages for the digi display so would have 5 and 12 VDC going off to the display pcb. So you would need to meter for AC and DC voltages.
What does and does not work on yours?
And Welcome BTW MM

Oh gawd looks like I've done it again
Another member less......
If I keep this up I'll be on my own

 

[Welderfix UK]

Lol, when you have been in the repair business a while you start touching 230vac on purpose in the morning just to wake you up!

 

[mad murph]

hi sorry it took so long to get the pics up. no diagrame though

 

[mike 109444]

might be worth reading through this post from some time back!
Guy at bottom of 1st page seams to have same fault as you. Can you check as he has done for voltage at the wire feed motor connections
http://www.mig-welding.co.uk/forum/showthread.php?t=6155

 

[mad murph]

was wondering has the guy that fixes the boards got an email adress ???