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Skotl,
I was given the machine second-hand some time ago. I used it briefly, but with little success, and it has been out of use ever since. I suspect that my lack of success was due to my ineptitude and not the limitations of the machine. However, I now need to resurrect the welder to rebuild my son's rotten BMW E30 and wanted to check the machine to see whether there were any modifications that would be prudent to make, rather than knowing that they were needed.
I have fitted a steel liner rather than the plastic one, and shall be using some Dinse plugs so that I can reverse the leads and use gasless wire as well.
Regards,
James.
I was given the machine second-hand some time ago. I used it briefly, but with little success, and it has been out of use ever since. I suspect that my lack of success was due to my ineptitude and not the limitations of the machine. However, I now need to resurrect the welder to rebuild my son's rotten BMW E30 and wanted to check the machine to see whether there were any modifications that would be prudent to make, rather than knowing that they were needed.
I have fitted a steel liner rather than the plastic one, and shall be using some Dinse plugs so that I can reverse the leads and use gasless wire as well.
Regards,
James.
Mattycoops43
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Hi peeps.
I am in the process of resurrecting my topmig 140 and putting it on gas, I did the roller mod when I first got it because it just seemed logical. Currently fitting a gas solenoid because the valve in the torch is junk and the trigger doesn't work.
I would like to do this wire feed mod, I am very competent on 12v vehicle stuff and general engineering etc, but I am not used to working on 240v systems. If I got the components and mounted them in my welder, is there anyone who is fairly local to me who would come and show me what to wire up where on my welder. As has been stated, if you muck up 240v it can be bad.
Thanks
Matt
I am in the process of resurrecting my topmig 140 and putting it on gas, I did the roller mod when I first got it because it just seemed logical. Currently fitting a gas solenoid because the valve in the torch is junk and the trigger doesn't work.
I would like to do this wire feed mod, I am very competent on 12v vehicle stuff and general engineering etc, but I am not used to working on 240v systems. If I got the components and mounted them in my welder, is there anyone who is fairly local to me who would come and show me what to wire up where on my welder. As has been stated, if you muck up 240v it can be bad.
Thanks
Matt
Mattycoops43
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Right. Bare with me please. New to this forum and I have been doing a lot of reading on here.
First off, I have had a really good re-read through the thread and I am confident now that I understand what's involved with this mod.
I am going to have a go at this myself, but I need a bit of help with the components, There are various links to different transformers, or order numbers listed, but most are out of date, the maplins one that sounded good is not coming up on there search.
It would really boost my confidence if someone who knows there stuff could link me to the correct transformer and bridge, preferably from maplins as i have a local one. I have had a look, but am only finding cased plug in power packs, not frame mounted transformers.
Thanks very much
First off, I have had a really good re-read through the thread and I am confident now that I understand what's involved with this mod.
I am going to have a go at this myself, but I need a bit of help with the components, There are various links to different transformers, or order numbers listed, but most are out of date, the maplins one that sounded good is not coming up on there search.
It would really boost my confidence if someone who knows there stuff could link me to the correct transformer and bridge, preferably from maplins as i have a local one. I have had a look, but am only finding cased plug in power packs, not frame mounted transformers.
Thanks very much
Mattycoops43
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Alternatively let me know if this is ok (it says can be used in series)
http://www.maplin.co.uk/p/12v-3a-chassis-transformer-n60jb
And this
http://www.maplin.co.uk/p/kbpc601-6a-bridge-rectifier-ar80b
I am a bit less sure on the bridge.
Appreciate any input.
http://www.maplin.co.uk/p/12v-3a-chassis-transformer-n60jb
And this
http://www.maplin.co.uk/p/kbpc601-6a-bridge-rectifier-ar80b
I am a bit less sure on the bridge.
Appreciate any input.
Mattycoops43
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If I search for AR84F I get this?
http://www.maplin.co.uk/p/kbpc2501-25a-bridge-rectifier-ar84f
I have misunderstood the current requirement for the bridge then? I thought it only needed to be suitable for the current draw of the motor.
Promise to stop spamming this thread now!
http://www.maplin.co.uk/p/kbpc2501-25a-bridge-rectifier-ar84f
I have misunderstood the current requirement for the bridge then? I thought it only needed to be suitable for the current draw of the motor.
Promise to stop spamming this thread now!
skotl
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First off, you'll need a 24V(ish) transformer, not a 12V one.
But I didn't go that way, I went this way instead --> http://www.mig-welding.co.uk/forum/...feed-power-supply-alternative-approach.11532/
This uses a laptop type (well, probably docking station more likely) switch mode 240V power supply that gives around 20VDC out. The trick is that, because switch mode PSUs don't like being turned rapidly on and off, the PSU is always on and its output is switched to the motor.
Bill had another awesome suggestion, which is that the relay shorts the connections at the motor when the trigger is released that, in turn, brakes the motor almost immediately when you release the trigger.
I'd strongly recommend going the permanent live 240V switched mode PSU front, with the addition of the shorting relay, rather that switching an iron-core power supply on and off.
But I didn't go that way, I went this way instead --> http://www.mig-welding.co.uk/forum/...feed-power-supply-alternative-approach.11532/
This uses a laptop type (well, probably docking station more likely) switch mode 240V power supply that gives around 20VDC out. The trick is that, because switch mode PSUs don't like being turned rapidly on and off, the PSU is always on and its output is switched to the motor.
Bill had another awesome suggestion, which is that the relay shorts the connections at the motor when the trigger is released that, in turn, brakes the motor almost immediately when you release the trigger.
I'd strongly recommend going the permanent live 240V switched mode PSU front, with the addition of the shorting relay, rather that switching an iron-core power supply on and off.
skotl
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Following on from ^^^ that post ^^^ I actually used a 21VDC 4A (~90 watt) Dell docking station power supply. If you have an IT department, go scrounge around them as, like us, they probably have a ton of these taking up space in a cupboard.
I place the PSU on the bottom tray, between the fan and the welding transformer (mine is a topmig, with quite a lot of space on the floor). I'm sure I have some pics lying around somewhere...
Edit: Found them!
This is the laptop docking station PSU, mounted between the fan and the welding trannie.
This is the relay, mounted on the floor.
I place the PSU on the bottom tray, between the fan and the welding transformer (mine is a topmig, with quite a lot of space on the floor). I'm sure I have some pics lying around somewhere...
Edit: Found them!
This is the laptop docking station PSU, mounted between the fan and the welding trannie.
This is the relay, mounted on the floor.
Mattycoops43
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I did consider going this way, and I still would, the only thing that put me off was the unreliability of these PSU's, my laptop has gone through about 4 in the last 18 months, they seem to be all cheap chinese units that just burn out.Following on from ^^^ that post ^^^ I actually used a 21VDC 4A (~90 watt) Dell docking station power supply. If you have an IT department, go scrounge around them as, like us, they probably have a ton of these taking up space in a cupboard.
I place the PSU on the bottom tray, between the fan and the welding transformer (mine is a topmig, with quite a lot of space on the floor). I'm sure I have some pics lying around somewhere...
Edit: Found them!
This is the laptop docking station PSU, mounted between the fan and the welding trannie.
This is the relay, mounted on the floor.
Having any transformer powering on and off I can understand being a bad idea, I thought the chassis mounted types were a bit more sturdy. Would the best option be a chassis mounted transformer and a bridge all running permanent live, and then into a relay to switch on and off?
I was thinking the transformer I linked to says it has two outputs so I was hoping it could supply 24v, think I might ring maplins and ask them to recommend the right one, if you define the search for transformers by 24v output, only one shows up which is a big white plastic cased thing which doesn't look like the right thing at all.
Anyway, I appreciate your input, and I can see how it's simpler to install a cased psu, I don't have any contact with tech people at work so would have to buy one. I don't mind the extra wiring if it's cheaper to install a chassis mount one, what would you recommend?
Matt
Mattycoops43
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Oh mine is a topmig 140 so looks exactly the same as yours.
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Look for industrial 24V DC PSU's, fleabay, RS, Farnell etc. there are many about, used in a lot of control panels. I've probably got some decent used ones kicking about if you're interested?
skotl
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Have a look at this link, which is what I did; http://www.mig-welding.co.uk/forum/...feed-power-supply-alternative-approach.11532/
You are absolutely correct that you don't with the PSU switching on and off with the torch - in Bill's design, the PSU is permanently on while the welder is powered up and it's the DC output that is switched through the relay.
That's a shame. If you're going to buy off ebay, then, defo look for a second hand docking station one. A quick search came up with exactly the model that I'm using at £17 - http://www.ebay.co.uk/itm/Genuine-O...Accessories_PowerSupplies&hash=item3f2d058151
Have fun!
Mattycoops43
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bought, thank you very much. Can you recommend a relay to finish the job?
skotl
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Yes indeedy 
I bought one of these; http://www.maplin.co.uk/p/round-base-10a-relay-240v-ac-3pdt-jg64u
and one of these; http://www.maplin.co.uk/p/round-base-10a240v-ac-dpdt-relay-jg60q
I bought one of these; http://www.maplin.co.uk/p/round-base-10a-relay-240v-ac-3pdt-jg64u
and one of these; http://www.maplin.co.uk/p/round-base-10a240v-ac-dpdt-relay-jg60q
Mattycoops43
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Yes indeedy
I bought one of these; http://www.maplin.co.uk/p/round-base-10a-relay-240v-ac-3pdt-jg64u
and one of these; http://www.maplin.co.uk/p/round-base-10a240v-ac-dpdt-relay-jg60q
That's two relays, I assume you meant a relay and a base? I have ordered the 3pdt relay and the 11 pin base to go with it, hope that's the right one.
I have been reading all these posts on doing various mods to SIP welders and my head is a bit full of different version of mods. Can you just clarify the dc side of the circuit for me? Am I right in thinking the dc supply goes into the pcb before the motor feed output so that the speed control knob is still used, so the original power wires to the motor are still intact, as the they are still used.
Thanks.
skotl
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The second link is the base, but sounds like you're sorted anyway 
Have a look at the second diagram here --> http://www.mig-welding.co.uk/forum/...feed-power-supply-alternative-approach.11532/
The diagram is not clear on one of the breaks; you need to cut two cables...
You break the existing wire feed voltage in, which is the right most connection on the PCB (and is marked as a break on the diagram).
You also break the existing +ve feed to the motor, which is the second from the right connection on the PCB. That is not explicit on the diagram but compare the two diagrams and look at the "Wire Feeder" component (aka motor). See that in the first diagram the right hand connection is wired to the second-from-right connection on the PCB. But in the second diagram, that connection is cut and we wire the C (common) connection from the relay to the +ve side of the motor, and the NO (normally open) connection is attached to the second-from-right connection on the PCB.
So the -ve output from the transformer is introduced to the -ve feed on the motor.
+ve from the transformer goes into the input feed on the PCB (the first wire you cut, farthest right)
The NC part of the relay (the relay is double throw, so you're just using one side) is connected to the wire out on the PCB (second pin from the right)
The common part of the relay is connected to the other side of the wire feed motor (and that's the only wire now going to that connector - that was the wire that you cut that used to go to wire-out / 2nd from the right on the PCB)
To summarise operation on the PCB;
S and R are the 240V permanent live inputs - You can attach the PSU live feed to there, but I didn't - I fed mine directly from the incoming power switch.
T is the switched 240V live, that becomes live when you pull the trigger. It feeds the welding transformer and we also use that to energise the relay when you pull the trigger. The other side of the relay is tied to the incoming neutral mains connection.
The rightmost pin on the PCB is the DC input that is switched to the wire feed motor when the trigger is pulled. We break this connection cos we want to replace its flakey input voltage with the more tightly regulated input from the new power supply.
The second-from-right pin is the switched DC output that feeds the motor when the trigger is pulled.
That last connection is floating (aka "off") when the trigger is not pulled. When you pull the trigger, the PCB closes the connection and it starts producing the ~20V from your new power supply. That is feed to the normally open (also aka "off") part of the relay.
But the relay is now energised because it gets 240V from the T connection when the trigger is pulled. When it is energised, it pulls the C pin over to the NO pin so that your 20V is now getting to the motor. Result = whirry, whirry.
When you let go of the trigger, the DC feed on second-from-right pin / NO on relay, is removed. The relay is de-energised, and its switch flips back to NC (Normally Closed). This shorts the two pins of the motor (the right hand wire is dragged to 0v / earth, same as the left hand wire) so the motor screeches to a halt.
Hope that helps!
Have a look at the second diagram here --> http://www.mig-welding.co.uk/forum/...feed-power-supply-alternative-approach.11532/
The diagram is not clear on one of the breaks; you need to cut two cables...
You break the existing wire feed voltage in, which is the right most connection on the PCB (and is marked as a break on the diagram).
You also break the existing +ve feed to the motor, which is the second from the right connection on the PCB. That is not explicit on the diagram but compare the two diagrams and look at the "Wire Feeder" component (aka motor). See that in the first diagram the right hand connection is wired to the second-from-right connection on the PCB. But in the second diagram, that connection is cut and we wire the C (common) connection from the relay to the +ve side of the motor, and the NO (normally open) connection is attached to the second-from-right connection on the PCB.
So the -ve output from the transformer is introduced to the -ve feed on the motor.
+ve from the transformer goes into the input feed on the PCB (the first wire you cut, farthest right)
The NC part of the relay (the relay is double throw, so you're just using one side) is connected to the wire out on the PCB (second pin from the right)
The common part of the relay is connected to the other side of the wire feed motor (and that's the only wire now going to that connector - that was the wire that you cut that used to go to wire-out / 2nd from the right on the PCB)
To summarise operation on the PCB;
S and R are the 240V permanent live inputs - You can attach the PSU live feed to there, but I didn't - I fed mine directly from the incoming power switch.
T is the switched 240V live, that becomes live when you pull the trigger. It feeds the welding transformer and we also use that to energise the relay when you pull the trigger. The other side of the relay is tied to the incoming neutral mains connection.
The rightmost pin on the PCB is the DC input that is switched to the wire feed motor when the trigger is pulled. We break this connection cos we want to replace its flakey input voltage with the more tightly regulated input from the new power supply.
The second-from-right pin is the switched DC output that feeds the motor when the trigger is pulled.
That last connection is floating (aka "off") when the trigger is not pulled. When you pull the trigger, the PCB closes the connection and it starts producing the ~20V from your new power supply. That is feed to the normally open (also aka "off") part of the relay.
But the relay is now energised because it gets 240V from the T connection when the trigger is pulled. When it is energised, it pulls the C pin over to the NO pin so that your 20V is now getting to the motor. Result = whirry, whirry.
When you let go of the trigger, the DC feed on second-from-right pin / NO on relay, is removed. The relay is de-energised, and its switch flips back to NC (Normally Closed). This shorts the two pins of the motor (the right hand wire is dragged to 0v / earth, same as the left hand wire) so the motor screeches to a halt.
Hope that helps!
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