Hi, I realise this is a bit of a thread revival, but I am in the middle of doing this mod, adding a 24v 4amp transformer & rectifier , and have noticed that there's a massive surge on startup and that the relay on the PCB has a black spot on the inside of the case which I think suggests it's on the way out (and all that welding current goes through the PCB). So my first thought was to replace the relay and add a 230v contactor to take the main load of switching the transformer on. Then I thought, so now I have a teeny 12v supply switching the small relay, switching in turn a contactor and another relay to turn on the 24v for the feed supply. It then occurred to me - why not just convert the torch switching to 24v, and do away with the little 12 v transformer and relay - I just need a single beefy 24v coil relay, or maybe one for mains and one for feed. Can anyone see a problem in doing that?
- Thread starter BillJ
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The main problem with relay specifications is that they are usually rated at 240 volts AC. When used on much lower DC voltages the current rating has to be divided by at least 4 to know how much current they can cope with on a regular basis. Also you should include a small non electrolytic capacitor across the contacts to eliminate the sparks generated as they open/close.
mike 109444
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Think you will find it switches the primary side on and off (240 low current) of the transformer rather than the secondary (15 to 24ish high current)
mike 109444
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mike 109444
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mike 109444
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Oh and welcome BTW 
wacky7791
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cheers mate! excellent site for info, completely rebuilding a mk1 escort and picked this mig up almost new for almost nothing so it'll be worth modding up to being usableOh and welcome BTW
Hi All,
I completed this modification over the weekend with a 24v 3a PSU with the DC output switched using a 240ac coil relay as per BillJ's setup on my SIP Migmate 130 Turbo.
The motor is working as it should be on the trigger but the speed of the motor doesn't adjust with the wire speed feed dial like it used to? Any suggestion?
Do I need to turn my trim down to bring my pot setting into allignment with the new power supply for the motor or does it sound like the pot is dead?
Any help is appreciated.
Thanks, James
I completed this modification over the weekend with a 24v 3a PSU with the DC output switched using a 240ac coil relay as per BillJ's setup on my SIP Migmate 130 Turbo.
The motor is working as it should be on the trigger but the speed of the motor doesn't adjust with the wire speed feed dial like it used to? Any suggestion?
Do I need to turn my trim down to bring my pot setting into allignment with the new power supply for the motor or does it sound like the pot is dead?
Any help is appreciated.
Thanks, James
skotl
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Sounds like you haven't successfully spliced the output of the new PSU into the circuit board.
Did you definitely cut the existing wire going from the middle link to the right hand pin (so only the +ve from the new transformer is going into the circuit board)?
Having done that, you should be able to use a multimeter to check that the voltage varies from the 2nd-to-right pin on that circuit board. Note that, on my SIP, the voltage would only vary while the torch trigger was being pulled.
Donsc
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isn't the black wire connected to the thermal sensor and the red also?on mine it is and I'm trying to get my 24V psu hooked up to run my feed motor but schematics anger me lol just an explanation of where my pos and neg from psu goes so I can still use existing speed control, but off of the psu and not off welder. Sighhhh
Slender Mouse
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Hi all,
Thanks for all the information on this site. It has helped me a great deal with my Migmate 170T over the years.
I would really like to do this wirefeed mod and have all the parts required.
My only problem is that the info I need has gone missing from this thread as its pretty old.
My Migmate is gas/gasless and is wired slightly differently to the Original posters.
It's same as In post #29 - (found on page 2 of this thread & pasted below)
The Reply #30 has all the info needed but the pics are gone and the external links are dead.
Can anyone help please?
Thanks again
#29
Has anyone done this mod at #1 on a gas/gasless Cosmo
as the PCB is wired differently
I assume tho' I am probably wrong not being an electronics expert
that CN5 on Bills diagram is a rectifier supplying a DC current to CN1,
On the diagram above CN5 isn't being powered directly from the transformer
but by a feed which appears to be linked to the torch which is switchable
depending on the mode being used.
Thanks for all the information on this site. It has helped me a great deal with my Migmate 170T over the years.
I would really like to do this wirefeed mod and have all the parts required.
My only problem is that the info I need has gone missing from this thread as its pretty old.
My Migmate is gas/gasless and is wired slightly differently to the Original posters.
It's same as In post #29 - (found on page 2 of this thread & pasted below)
The Reply #30 has all the info needed but the pics are gone and the external links are dead.
Can anyone help please?
Thanks again
#29
Has anyone done this mod at #1 on a gas/gasless Cosmo
as the PCB is wired differently
I assume tho' I am probably wrong not being an electronics expert
that CN5 on Bills diagram is a rectifier supplying a DC current to CN1,
On the diagram above CN5 isn't being powered directly from the transformer
but by a feed which appears to be linked to the torch which is switchable
depending on the mode being used.
ginettaman
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- York
I finally joined your forum as I read up the posts on modifying Sip machines. I've spent hours working on my Sip 105 turbo and finally done this mod with a PSu and relay. I didn't find that the relay connection to short the motor when releasing the trigger seemed to make any difference so I left that connection off.
Sadly the motor is still jittery and so I feel the motor is the problem rather than the power supply. At low voltage it's up and down so It's still crap sadly. I've borrowed an old Sip 120 and a Sip 170 but both those need work to recommission but I hope they will work better eventually.
Sadly the motor is still jittery and so I feel the motor is the problem rather than the power supply. At low voltage it's up and down so It's still crap sadly. I've borrowed an old Sip 120 and a Sip 170 but both those need work to recommission but I hope they will work better eventually.
Hello, and welcome to the Forum!
Which Ginettas are you into? My favourites are the G4, the G15, and the G21. I have never owned one, but I used to have a Fairthorpe Electron, and I own a Piper P2.
I would suggest the following hints about jittery wirefeed:
- worn brushes or bearings on the motor?
- too much drag on the spindle of the MIG wire spool?
- clean out and put fresh grease in the gearbox
I think the wirespeed controller on the PCB is just a simple variable-current driver, using a TIP35C or similar power transistor to reduce the current. In other words, it is just a big rheostat ( variable resistor, like a Scalextric hand controller ). At low speed settings, most of the supply voltage is dropped across the transistor, so the motor cannot produce much torque. The solution, especially after you have gone to the trouble of installing a stabilised power source, is to take the next step and fit a modern Pulse-width Modulated ( PWM ) motor speed controller. This circuit feeds variable-width pulses at the full 12v or 24v to the motor, so full torque is available at all speeds. The same type of circuit is used in the trigger control of a modern cordless drill.
Typical example:
https://www.ebay.co.uk/itm/12V-36V-...-Controller-Switch-12V-24V-3A-AL/400755823151
Finally, you may need a complete new wirefeed assembly - plastic:
https://www.ebay.co.uk/itm/Duty-MIG...d-Machine-for-Mig-Welder-Machine/383671546997
or metal:
https://www.ebay.co.uk/itm/DC-24V-0...e-Wire-Drive-Motor-Feed-Feeder-D/233682904367
or including Eurotorch socket conversion:
https://www.ebay.co.uk/itm/Assembly...ne-Welder-Euro-Connector-24V-12V/264894724829
Which Ginettas are you into? My favourites are the G4, the G15, and the G21. I have never owned one, but I used to have a Fairthorpe Electron, and I own a Piper P2.
I would suggest the following hints about jittery wirefeed:
- worn brushes or bearings on the motor?
- too much drag on the spindle of the MIG wire spool?
- clean out and put fresh grease in the gearbox
I think the wirespeed controller on the PCB is just a simple variable-current driver, using a TIP35C or similar power transistor to reduce the current. In other words, it is just a big rheostat ( variable resistor, like a Scalextric hand controller ). At low speed settings, most of the supply voltage is dropped across the transistor, so the motor cannot produce much torque. The solution, especially after you have gone to the trouble of installing a stabilised power source, is to take the next step and fit a modern Pulse-width Modulated ( PWM ) motor speed controller. This circuit feeds variable-width pulses at the full 12v or 24v to the motor, so full torque is available at all speeds. The same type of circuit is used in the trigger control of a modern cordless drill.
Typical example:
https://www.ebay.co.uk/itm/12V-36V-...-Controller-Switch-12V-24V-3A-AL/400755823151
Finally, you may need a complete new wirefeed assembly - plastic:
https://www.ebay.co.uk/itm/Duty-MIG...d-Machine-for-Mig-Welder-Machine/383671546997
or metal:
https://www.ebay.co.uk/itm/DC-24V-0...e-Wire-Drive-Motor-Feed-Feeder-D/233682904367
or including Eurotorch socket conversion:
https://www.ebay.co.uk/itm/Assembly...ne-Welder-Euro-Connector-24V-12V/264894724829
ginettaman
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- York
I've had a G21s, a G4S4, a G15, a G27 and now. Dare G4. I've done most of the mods but the 105 motor and arc are never consistent. May be me but I'm sure is not all down to me. When the small motor runs slow it's only running at around 3v so it guess its then struggling to run. I've read somewhere about build a capacitor circuit to make the motor run better but have really lost too much time with the 105.
