BChild
SIP - enough with the mods!!!!
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No probs with the late reply
We've definately seen different boards on SIP and definately different connection arrangements
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No probs with the late reply
We've definately seen different boards on SIP and definately different connection arrangements
katana
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Well, I have finally dusted off the welder and started re-checking the modded wiring. I have found some very strange results....
The transformer (a 48V) a Legrand Safety isolating type is wired correcting...wired to supply 24v (measured at 24.5V AC).
Wired to the bridge and the outputs checked from terminals +ve and -ve(measured 28.5V DC) an increase of 4V (????)
This is where things get very weird....wires connected to bridge and measured at the other, unconnected end of the wire ie from the +ve and -ve 86.4V DC
....some how the voltage increase 3 times just by passing through a wire ???? There are no shorts and no other obvious explaination.
What on earth is going on .......any ideas please.
Thanks
David
I have re-checked all measurements and have found that with the output wires (+ve and -ve) left connected to the bridge so that the 'connectors' on the bridge (+ve and -ve) are slightly exposed. I can measure 38V DC. Remove the wires and the voltage on the bridge connectors drops to around 28V .....stranger and stranger ???!!
The transformer (a 48V) a Legrand Safety isolating type is wired correcting...wired to supply 24v (measured at 24.5V AC).
Wired to the bridge and the outputs checked from terminals +ve and -ve(measured 28.5V DC) an increase of 4V (????)
This is where things get very weird....wires connected to bridge and measured at the other, unconnected end of the wire ie from the +ve and -ve 86.4V DC
....some how the voltage increase 3 times just by passing through a wire ???? There are no shorts and no other obvious explaination.What on earth is going on .......any ideas please.
Thanks
David
I have re-checked all measurements and have found that with the output wires (+ve and -ve) left connected to the bridge so that the 'connectors' on the bridge (+ve and -ve) are slightly exposed. I can measure 38V DC. Remove the wires and the voltage on the bridge connectors drops to around 28V .....stranger and stranger ???!!
Wedg1e
They call me Mr. Bodge-angles
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It's normal for the output of a full-wave bridge to be higher than the nominal AC you put into it - I think typically 1.4x higher.
The transformer is 48v CT - centre-tapped, which means you effectively have two identical windings joined in series, with all three connections accessible. This results in 24-0-24v AC, so if you only use the CT and one end you see 24v. Across the two ends it'll be 48v.
The reason I think your voltage readings off the bridge look odd is because with nothing connected to the bridge, the internal diodes are only conducting a microscopic amount to feed your meter. With the wiring connected the diodes are conducting hard so you see the full voltage.
The transformer is 48v CT - centre-tapped, which means you effectively have two identical windings joined in series, with all three connections accessible. This results in 24-0-24v AC, so if you only use the CT and one end you see 24v. Across the two ends it'll be 48v.
The reason I think your voltage readings off the bridge look odd is because with nothing connected to the bridge, the internal diodes are only conducting a microscopic amount to feed your meter. With the wiring connected the diodes are conducting hard so you see the full voltage.
stuff to fix
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I dont understand quite what is happening but can make a few observations.
What sort of meter have you got? If it is an electronic one with very high input impedance, it is possible this may affect the result as compared to a cheap dial one which puts a bit more load on the circuit. Just a thought. I dont see how it applies here, but for example, if you have a pretty dead battery and use a high impedance meter, it may give a much better voltage than a moving coil one which draws more current, just enough to show the battery is incapable of running anything and its voltage collapses as soon as it has any load.
Is your meter set to DC volts or AC volts? The point is that what is coming out of the transformer is ac, what is coming out of the rectifier is intermittent dc. When measuring ac, a meter should diplay the RMS value (root mean square), which is a sort of average value. AC goes backwards and then forwards, so the actual average
voltage is 0. The meter has to sort this out and uses some sort of bridge internally to rectify the ac and then average it. If you measure the output from your bridge with the DC range, I am not quite sure what you will get. Some sort of average. If you are using a very high impedance meter, then what you might get is not the average value, but the peak value. If the average value is 25V, the peak will be about 1/3 more.
If you add smoothing capacitors to the output from the bridge then they will charge up to the maximum voltage coming out. Once you start putting a load on them, this will fall away because the transformer is only putting out its highest voltage for part of the time.
The diodes in the bridge actually lose voltage. About 0.5 volts is needed to push current through a diode and is therefore used up.
The actual output from the transformer will change as you put more load on it. If the winding has a resistance of 1ohm and you take i amp from it, then it will drop 1 volt across the wire inside the transformer. Thats why the weld transformer has very thick wire. So although a transformer might claim to be a certain voltage output, it does vary a bit depending on how you use it. It may be specified as 24V at some current, eg at 48VA ie 2 A. Shouldnt happene here, but if you have a transformer with two secondary windings which you use for different things, then if the load on one winding increases it will affect the voltage on the other. Thats because there is limited magnetic field inside the transformer and one winding is sucking it up. Transformers rated for more power are physically bigger partly so there is more iron inside them to carry the magnetic field.
anyway, if what you did was disconnect some wires with capacitors on the ends somewhere, with capacitors connected you would expect a higher measured voltage.
A very high impedance meter can also give odd results when it is not connected to anything. The magntic field in the transformer or even just from a mains wire can induce a voltage in other wires nearby. The amount of current you can get is tuly tiny, but if the meter has high enough input impedance, it might give a big reading from something apparently disconnected. This can happen with house wiring for example. Some modern fluorescent bulbs can flash intermittently if placed in old style wiring circuits which did not have earths. Induction between the insulated wires can produce enough voltage to slowly charge up the electronics in some kinds of bulb and give a brief dim flash...which you suddenly see when you walk round the house in the dark!
What sort of meter have you got? If it is an electronic one with very high input impedance, it is possible this may affect the result as compared to a cheap dial one which puts a bit more load on the circuit. Just a thought. I dont see how it applies here, but for example, if you have a pretty dead battery and use a high impedance meter, it may give a much better voltage than a moving coil one which draws more current, just enough to show the battery is incapable of running anything and its voltage collapses as soon as it has any load.
Is your meter set to DC volts or AC volts? The point is that what is coming out of the transformer is ac, what is coming out of the rectifier is intermittent dc. When measuring ac, a meter should diplay the RMS value (root mean square), which is a sort of average value. AC goes backwards and then forwards, so the actual average
voltage is 0. The meter has to sort this out and uses some sort of bridge internally to rectify the ac and then average it. If you measure the output from your bridge with the DC range, I am not quite sure what you will get. Some sort of average. If you are using a very high impedance meter, then what you might get is not the average value, but the peak value. If the average value is 25V, the peak will be about 1/3 more.
If you add smoothing capacitors to the output from the bridge then they will charge up to the maximum voltage coming out. Once you start putting a load on them, this will fall away because the transformer is only putting out its highest voltage for part of the time.
The diodes in the bridge actually lose voltage. About 0.5 volts is needed to push current through a diode and is therefore used up.
The actual output from the transformer will change as you put more load on it. If the winding has a resistance of 1ohm and you take i amp from it, then it will drop 1 volt across the wire inside the transformer. Thats why the weld transformer has very thick wire. So although a transformer might claim to be a certain voltage output, it does vary a bit depending on how you use it. It may be specified as 24V at some current, eg at 48VA ie 2 A. Shouldnt happene here, but if you have a transformer with two secondary windings which you use for different things, then if the load on one winding increases it will affect the voltage on the other. Thats because there is limited magnetic field inside the transformer and one winding is sucking it up. Transformers rated for more power are physically bigger partly so there is more iron inside them to carry the magnetic field.
anyway, if what you did was disconnect some wires with capacitors on the ends somewhere, with capacitors connected you would expect a higher measured voltage.
A very high impedance meter can also give odd results when it is not connected to anything. The magntic field in the transformer or even just from a mains wire can induce a voltage in other wires nearby. The amount of current you can get is tuly tiny, but if the meter has high enough input impedance, it might give a big reading from something apparently disconnected. This can happen with house wiring for example. Some modern fluorescent bulbs can flash intermittently if placed in old style wiring circuits which did not have earths. Induction between the insulated wires can produce enough voltage to slowly charge up the electronics in some kinds of bulb and give a brief dim flash...which you suddenly see when you walk round the house in the dark!
Maybe along these lines.:http://www.play-hookey.com/ac_theory/ps_v_multipliers.html
Robert
Robert
katana
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Thank you all very much for your replies, greatly appreciated 
The multimeter used is digital of 'average' quality.
The voltage from the transformer was measured AC volts (24.5 V)
The voltage from the bridge +ve and -ve were measured DC volts as were all the other readings including the unconnected ends of the wires attached to the +ve/-ve terminals of the bridge. (86.4V).
Previously with everything connected up the wire feed motor was constantly running (not controlled by the trigger) So was checking through connections etc to rectify the problem. Whilst doing this I found these readings and was concerned that 80 odd volts would seriously damage PCB/motor. I did wonder that an 'incomplete' circuit could give you some strange readings....but 84V was a bit much to ignore. I understand (simply) how the bridge works ie only letting (half the 'waves') of the AC to pass through the internal diodes so resulting in DC output (Like I said I understand it simply
) However I would not expect it to be a higher voltage. With the transformer wired up with the constant feed problem I originally had, I had measured 36V DC at the wire feed motor.....so voltage was a problem before.
Could the bridge be faulting ? I assume I can check to make sure current only passes in one direction on the terminals ? Can diodes become U/S by allowing current to flow in both directions, instead of one ?
Thank you
Kind Regards David
The multimeter used is digital of 'average' quality.
The voltage from the transformer was measured AC volts (24.5 V)
The voltage from the bridge +ve and -ve were measured DC volts as were all the other readings including the unconnected ends of the wires attached to the +ve/-ve terminals of the bridge. (86.4V).
Previously with everything connected up the wire feed motor was constantly running (not controlled by the trigger) So was checking through connections etc to rectify the problem. Whilst doing this I found these readings and was concerned that 80 odd volts would seriously damage PCB/motor. I did wonder that an 'incomplete' circuit could give you some strange readings....but 84V was a bit much to ignore. I understand (simply) how the bridge works ie only letting (half the 'waves') of the AC to pass through the internal diodes so resulting in DC output (Like I said I understand it simply
) However I would not expect it to be a higher voltage. With the transformer wired up with the constant feed problem I originally had, I had measured 36V DC at the wire feed motor.....so voltage was a problem before.Could the bridge be faulting ? I assume I can check to make sure current only passes in one direction on the terminals ? Can diodes become U/S by allowing current to flow in both directions, instead of one ?
Thank you
Kind Regards David
stuff to fix
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I dont think i could solve this from what you have said, which I agree doesnt make sense. R Kraft posted a link to voltage multiplier circuits. I dont know whether if the terminals in a bridge get mixed up it is possible to make a voltage multiplier by accident? (anyone?) You need capacitors to make a voltage multiplier too, but you are using a digital meter which will have a very high input impedance even if a cheap one.. That means it draws a tiny current so the inherent capacitance in other components might be enough to give a measurable reading. If you put a load on the circuit, say a 10K resistor, that would likely be enough to show if the measured voltage drops dramatically. i know, you probably dont have a drawer full of these things handy so that probably doesnt help.
If you have an electronic meter like one I own, it reads wrong on some scales, in my case showing about half the correct reading. Do you get the same answer if you change scales?(but if it is faulty, it could affect all. I mean, if there is more than one range for DC volts. I dont mean try an inappropriate range)
If diodes are conducting both ways what usually happens is a bang followed by not conducting either way. (after you fix the fuse)
I think you have said that at the bridge output you get 28.5V. Arguably acceptable if the readings arent completely accurate and are floating. Then at the end of a couple of wires you get a bigger reading? What do you get with one meter probe on the bridge and the other at the end of a wire? And then the same measuring along just the other wire? (so test if one wire makes sense and the other doesnt, which would suggest there is something strange about just one?) Does it stay the same if you move the wires about a bit?
it might help of you posted some more pictures so we can see the rest of the wiring. I have been reading all the threads on here about different mods and different models of welder So Im not sure exactly which we are talking about.
If you have an electronic meter like one I own, it reads wrong on some scales, in my case showing about half the correct reading. Do you get the same answer if you change scales?(but if it is faulty, it could affect all. I mean, if there is more than one range for DC volts. I dont mean try an inappropriate range)
If diodes are conducting both ways what usually happens is a bang followed by not conducting either way. (after you fix the fuse)
I think you have said that at the bridge output you get 28.5V. Arguably acceptable if the readings arent completely accurate and are floating. Then at the end of a couple of wires you get a bigger reading? What do you get with one meter probe on the bridge and the other at the end of a wire? And then the same measuring along just the other wire? (so test if one wire makes sense and the other doesnt, which would suggest there is something strange about just one?) Does it stay the same if you move the wires about a bit?
it might help of you posted some more pictures so we can see the rest of the wiring. I have been reading all the threads on here about different mods and different models of welder So Im not sure exactly which we are talking about.
stuff to fix
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Im afraid I dont understand what you are doing (see request above for pictures). Which mod are you doing? Wiring varies a bit from model to model. The Black wire originally went to the +ve output from the big diodes fed by the weld transformer (big one). The white wire went to drive the motor. The blue wire went to the switch on the torch. The red wire goes to different places depending on your model. It may go to the same place as the black wire, or it may go further on, if your welder has some terminals to swap around the output from the weld transformer? (on models which do welding both with gas and without which means you have to swap polarity)
The red and blue wires are part of the circuit which runs the relay which switches on power to the big transformer. I think you do not touch them. There is a small transformer (black square box) on the control board which runs this circuit. The relay on the board should click when the torch button is pressed and the big transformer should come on. The relay is next to the transformer. It may have a transparent box so you can see the terminals.
What mod are you doing, how is your new transformer powered? Are you powering it from the output of this relay so it comes on with the weld transformer?
This picture is from the start of the thread and shows wiring changes which you are copying? Is you board the same as the one shown so you are powering your transformer as in the picture from wires piggybacked onto the black terminals shown? i think the extra wires powering the new transformer are the red and black with blue crimps on them. Some boards in some machines do not have three contacts on the black connector but only two. In that case you probably do NOT connect to those two. The bottom and middle ones in this picture are the live mains in and if the top terminal is not here but moved to next to the relay, you have to connect to it on that side of the board.
katana
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A BIG Thank you to all those that responded and tried to help....started from 'scratch'....disconnecting all wires and then reconnecting them as per the original post ......now works fine 
I have no idea why I was getting 'strange readings' or why it didn't work before (certain wire connections are exactly as before) ....but wire feed now works from the trigger....checked DC voltages at the wire feed motor ...low speed around 3V fast....22+V .Haven't had time to lay a weld ....but hopefully everything is OK. Will post whether improvement has been made, thanks again
All the best
David
I have no idea why I was getting 'strange readings' or why it didn't work before (certain wire connections are exactly as before) ....but wire feed now works from the trigger....checked DC voltages at the wire feed motor ...low speed around 3V fast....22+V .Haven't had time to lay a weld ....but hopefully everything is OK. Will post whether improvement has been made, thanks againAll the best
David
Hi People,
Thanks for all the mods to the SIP/Cosmo. I did the following mods:
1: support strap on the roller arm pivot
2: trimpot resistor change (500R in parallel with 180R)
3: separate DC for drive controller
4: use a piece of stainless steel wool with a peg on the wire as it comes off the spool to clean the wire.
5: drilled a hole in the spool tension nut so I can place a wire in it to stop it self tightening/loosening as the spool turns
Which turned a crap and basically useless welder that I was about to throw in the bin into a reasonable unit which can give welds as good as any machine costing much much more!!!
Just a quick note: I have a slightly different model (in Australia these are marketed under the BOSS brand) with some slight changes to the circuit board and wiring. I have included a picture with A, B and C marked on it. If you don't do it this way you will get the "constant feed" problem!
Notes on DC Drive change for this BOSS 150H model:
0: I did piggy back connections by making "pigtails" with matching crimp on connectors.
1: Connect one 240V primary of new transformer to 240V Supply Live (top left corner of C)
2: Connect other 240V primary of new transformer to switched side of trigger relay (lower connector at B in pic) which connects 240V Supply Neutral when the trigger fires.
3: Disconnect -ve side of motor (originally to -ve of main rectifier) and isolate
4: Split +ve input (Black wire at C) and add matching crimp terminals so you can reconnect original setup but isolate original ~+24V from rectifier.
5: Connect +ve from bridge to input on circuit board (black wire at C that you split earlier)
6: Connect -ve from bridge to -ve on motor
7: Add small greencap (I used 47nF) across motor (bottom in A) to negate HF spikes. You can add as much capacitance as you like but the more you add to smooth drive the more "run on" and "slow start" you will get.
7: Adjust trimpot to give a good speed range (just below green connector in C). Note that you may need to do the variable trimpot mod to get usable adjustment; especially if you have >23V DC!
And that's all folks! Thanks again to all those who have contributed :-)
Thanks for all the mods to the SIP/Cosmo. I did the following mods:
1: support strap on the roller arm pivot
2: trimpot resistor change (500R in parallel with 180R)
3: separate DC for drive controller
4: use a piece of stainless steel wool with a peg on the wire as it comes off the spool to clean the wire.
5: drilled a hole in the spool tension nut so I can place a wire in it to stop it self tightening/loosening as the spool turns
Which turned a crap and basically useless welder that I was about to throw in the bin into a reasonable unit which can give welds as good as any machine costing much much more!!!
Just a quick note: I have a slightly different model (in Australia these are marketed under the BOSS brand) with some slight changes to the circuit board and wiring. I have included a picture with A, B and C marked on it. If you don't do it this way you will get the "constant feed" problem!
Notes on DC Drive change for this BOSS 150H model:
0: I did piggy back connections by making "pigtails" with matching crimp on connectors.
1: Connect one 240V primary of new transformer to 240V Supply Live (top left corner of C)
2: Connect other 240V primary of new transformer to switched side of trigger relay (lower connector at B in pic) which connects 240V Supply Neutral when the trigger fires.
3: Disconnect -ve side of motor (originally to -ve of main rectifier) and isolate
4: Split +ve input (Black wire at C) and add matching crimp terminals so you can reconnect original setup but isolate original ~+24V from rectifier.
5: Connect +ve from bridge to input on circuit board (black wire at C that you split earlier)
6: Connect -ve from bridge to -ve on motor
7: Add small greencap (I used 47nF) across motor (bottom in A) to negate HF spikes. You can add as much capacitance as you like but the more you add to smooth drive the more "run on" and "slow start" you will get.
7: Adjust trimpot to give a good speed range (just below green connector in C). Note that you may need to do the variable trimpot mod to get usable adjustment; especially if you have >23V DC!
And that's all folks! Thanks again to all those who have contributed :-)
Just thought I would add a few notes to the previous post (cant seem to edit it ???).
1: If you are considering adding a 3 terminal regulator power supply after the trans/bridge forget it!! I have fried a dozen LM317s and an LM338 in the process of trying. Protection diodes (I had one in every conceivable position: 5 in all!) or capacitors (ceramics, polyesters and electro) will NOT prevent trashing the LM317!
Although the regulator works in the unloaded situation as soon as you connect it to the motor it works for 10-20 seconds and then the 317 self destructs!
Would be very interested to hear of any alternative suggestions as to why the 317 regulator gets fried all the time??
Edited 24hrs later: I did connect up a decent MM with a good record function and saw a peak of 2.5A at startup. But this should not be enough to kill the 317, the short circuit protection should just shut it down. Will have to follow this up on some electronics forums....
2: The 100VA transformer is probably overkill as the motor only draws about 500mA under load. Which at 24V is only 12VA. However the startup current is at least 2.5A!
3: You can use the same 12V that drives the existing PCB mounted relay to drive another relay to send drive to the motor. That way you can use capacitors to smooth the drive voltage.
4: I decided to connect the transformer permanently to the 240V switch (rather than via the switched relay) as it gives a smoother start up with little settling time. So circuit looks like:
main switch -->240-->transform/bridge--->+24V--->variable--->capacitors--->Relay--->motor
1: If you are considering adding a 3 terminal regulator power supply after the trans/bridge forget it!! I have fried a dozen LM317s and an LM338 in the process of trying. Protection diodes (I had one in every conceivable position: 5 in all!) or capacitors (ceramics, polyesters and electro) will NOT prevent trashing the LM317!
Although the regulator works in the unloaded situation as soon as you connect it to the motor it works for 10-20 seconds and then the 317 self destructs!
Would be very interested to hear of any alternative suggestions as to why the 317 regulator gets fried all the time??
Edited 24hrs later: I did connect up a decent MM with a good record function and saw a peak of 2.5A at startup. But this should not be enough to kill the 317, the short circuit protection should just shut it down. Will have to follow this up on some electronics forums....
2: The 100VA transformer is probably overkill as the motor only draws about 500mA under load. Which at 24V is only 12VA. However the startup current is at least 2.5A!
3: You can use the same 12V that drives the existing PCB mounted relay to drive another relay to send drive to the motor. That way you can use capacitors to smooth the drive voltage.
4: I decided to connect the transformer permanently to the 240V switch (rather than via the switched relay) as it gives a smoother start up with little settling time. So circuit looks like:
main switch -->240-->transform/bridge--->+24V--->variable--->capacitors--->Relay--->motor
Last edited:
Just thought I would wrap up the problems with the latest mod.
As stated above I tried to "cheapskate" by driving the motor with a cheap adjustable linear regulator i.e. the LM317 BUT they kept blowing up. After much investigation found it was a combination of 80V (yes 80V!!!) back spikes that the "slow" protection diodes did not handle. Now I have a permanently connected PWM which drives the motor through a second relay (in parallel with the main PCB mounted one). Only minor problem is there is a small amount of wire "run on" after trigger release; about 1.5cm.
So the lessons are:
1: even small motors generate BIG back EMF which are not handled by slow diodes and kill even allegedly indestructible ICs!
2: don't cheapskate; just do it properly in the first place! (yeah I know buy a decent MIG instead of this cheapie!).
As stated above I tried to "cheapskate" by driving the motor with a cheap adjustable linear regulator i.e. the LM317 BUT they kept blowing up. After much investigation found it was a combination of 80V (yes 80V!!!) back spikes that the "slow" protection diodes did not handle. Now I have a permanently connected PWM which drives the motor through a second relay (in parallel with the main PCB mounted one). Only minor problem is there is a small amount of wire "run on" after trigger release; about 1.5cm.
So the lessons are:
1: even small motors generate BIG back EMF which are not handled by slow diodes and kill even allegedly indestructible ICs!
2: don't cheapskate; just do it properly in the first place! (yeah I know buy a decent MIG instead of this cheapie!).
Diode across it like this
http://arduino.cc/forum/index.php?topic=4364.0;wap2
But make it a zener one to clamp over voltage too?
There is talk of using "fast recovery"diodes?
http://arduino.cc/forum/index.php?topic=4364.0;wap2
But make it a zener one to clamp over voltage too?
There is talk of using "fast recovery"diodes?
Just thought I would put up the final circuit mods to both the motor controller and main welder circuit.
If you really wanted to go the whole hog you could do a PIC controller to control delays etc and/or use a solid state zero crossing relay on the main PCB. But why bother; with these (and the drive roller) mods this junk welder welds as good as a $5000 machine at all except at the top of the amps range i.e. 150A in my case
NOTE: If you don't know what you are doing with 240 then get someone who does to do mods.
The PWM is a Jaycar kit KC5225. I had to add a 1k resistor in series with the control POT as the adjustment was too coarse and you don't need to bottom 30% of the PWM range anyway.
I also stopped any run on by using the NC terminal of the second relay to short the motor which stops it dead when the trigger is released.
The BIG capacitor across the welding circuit is minimum 100V and needs around min 10A ripple (even so it does get warm and will probably not last very long......). It also needs a bleed resistor!!!!!
Anyway thats my 2c worth, I now have a welder that works and hope you do too
If you really wanted to go the whole hog you could do a PIC controller to control delays etc and/or use a solid state zero crossing relay on the main PCB. But why bother; with these (and the drive roller) mods this junk welder welds as good as a $5000 machine at all except at the top of the amps range i.e. 150A in my case
NOTE: If you don't know what you are doing with 240 then get someone who does to do mods.
The PWM is a Jaycar kit KC5225. I had to add a 1k resistor in series with the control POT as the adjustment was too coarse and you don't need to bottom 30% of the PWM range anyway.
I also stopped any run on by using the NC terminal of the second relay to short the motor which stops it dead when the trigger is released.
The BIG capacitor across the welding circuit is minimum 100V and needs around min 10A ripple (even so it does get warm and will probably not last very long......). It also needs a bleed resistor!!!!!
Anyway thats my 2c worth, I now have a welder that works and hope you do too
Just an interesting note; In the photo you can see the relatively smooth CRO trace with the added capacitor while welding on the High/Min setting. The scale is 10V/division so the the voltage is ~18V with a peak of ~26.
However although the welder actually welds surprisingly well with the mods it sounds "nicer" on the High settings, it has that pleasing "fizz" sound but on the "Low" settings it had more of a crackling/popping sound: on the Low settings the CRO trace is more "jagged" (see second photo). Why this should be I do not know, perhaps the High windings have better regulation, the wire speed is not optimal or perhaps the switch is dicky but as the other photo shows the trace is not as "clean". A Digital CRO owuld probably pick this up better; its hard to weld while adjusting the trigger on an old analogue CRO :-(
However although the welder actually welds surprisingly well with the mods it sounds "nicer" on the High settings, it has that pleasing "fizz" sound but on the "Low" settings it had more of a crackling/popping sound: on the Low settings the CRO trace is more "jagged" (see second photo). Why this should be I do not know, perhaps the High windings have better regulation, the wire speed is not optimal or perhaps the switch is dicky but as the other photo shows the trace is not as "clean". A Digital CRO owuld probably pick this up better; its hard to weld while adjusting the trigger on an old analogue CRO :-(
I know that I am resurrecting an old thread, but I was wondering whether any knows whether the Sealey MightyMig 100 uses a similar arrangement for powering the feed motor? I have yet to take the case off from the machine, but shall be making a few modifications to it soon and this idea sounds sensible.
Regards,
James.
Regards,
James.
skotl
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It should be pretty easy to spot, if you know what a transformer looks like.
It will look a little like this;
Or this;
Most SIP welders only have one of these (and they tend to look a lot more "industrial") so if you can only spot one big lump of iron with some serious iron solid core cable coming out, then your welder is using the same transformer to power both the arc and the wire feed.
It will look a little like this;
Or this;
Most SIP welders only have one of these (and they tend to look a lot more "industrial") so if you can only spot one big lump of iron with some serious iron solid core cable coming out, then your welder is using the same transformer to power both the arc and the wire feed.
I took the cover off for a look and, unless I am misunderstanding it, my Sealey has a separate supply for the feed motor. The board with the power control for the motor is fed directly from the power switch and appears to have its own transformer on board.
