SIP Topmig Super 196 no wire feed, of course!

[the snooper]

Just to check, following on from this post, if I re-plug the relay using the good contacts the, whole thing should turn on with the on/off switch. I should see the motor turn and there should be voltage across the torch and earth lead? If I have re-connected the torch trigger, it will stop the motor. I am happy to do this to check the other components but I just wanted to confirm what to expect when I turn it on.

Cheers,
Peter

yes you should see the motor turn and the torch will become live but due to the type of relay the torch trigger may work in reverse ie squeezing the trigger will stop it running

 

[the snooper]

when you go to buy a new relay you only need a 12 volt (30 amp minimum) single pole single throw normally open relay

 

[Peter Relton]

when you go to buy a new relay you only need a 12 volt (30 amp minimum) single pole single throw normally open relay

Ta for that. That kind of relay will make it simpler. As posted before, there is a very good LX shop near me and with all the good advice I have received here, I am sure they will be able to supply the right thing. I will post later how replugging the old one goes! Fingers crossed.

 

[Peter Relton]

The new relay has arrived. I will test it tomorrow. Fingers crossed!

 

[Peter Relton]

[QUOTEsnooper, post: 771275, member: 8528"]yes you should see the motor turn and the torch will become live but due to the type of relay the torch trigger may work in reverse ie squeezing the trigger will stop it running[/QUOTE]
So I plugged up the new relay. It clicks and the machine hums but no action at the motor. I unplugged it and joined the main wires, turned it on and got the same lovely humming but no motor. There appeared to be a voltage across the torch and earth but I was rushing and not sure what the reading should be. Should I check the output to the motor at the PCB or anything else?

 

[Peter Relton]

The motor is fine. I've had it out and run it across my car battery.

 

[Peter Relton]

A car battery can provide far more current than your welder's speed controller can - which may hide a 'last legs' motor...

See if there's any output (on torch/earth as well as on motor wires) as a first step.

Just to check, it's AC at the torch/earth and AC or DC at the motor? What voltage should I expect at each point?

 

[Peter Relton]

Should be DC at both...

On a mid setting I'd 'expect' anywhere around 20-45 volts 'twixt torch and earth, with maybe around half that at the motor wires.

Depending on smoothing, you'll get a 'reading' of more or less 'some' volts if your meter is set to AC...

The range of voltage isn't hard limits btw, the characteristics of the transformer will affect what the open circuit voltage is and they are unknown to me

Hi, I had a quick test. I think I got 20v between the torch and earth. I then measured between the "in" to the motor from the pcb and the out where it connects to the large collection of wires going to the main transformer. I got about the same, 20v. That seems a bit high? I then reconnected the pcb to the motor and nothing works at all! No clicking from the relay so I must have done something strange. I checked voltage at the small transformer that supplies the pcb and that was fine, just nothing else happened. I didn't have time for any further investigation.

 

[Peter Relton]

Should be DC at both...

On a mid setting I'd 'expect' anywhere around 20-45 volts 'twixt torch and earth, with maybe around half that at the motor wires.

Depending on smoothing, you'll get a 'reading' of more or less 'some' volts if your meter is set to AC...

The range of voltage isn't hard limits btw, the characteristics of the transformer will affect what the open circuit voltage is and they are unknown to me

OK. Latest update. I have power at the torch. Both the main relay and gas relay are working. I have tested the motor again in situ with a battery charger. I appear to have no power from the pcb to the motor. I have checked across the power out from the pcb to the wire out of the motor and there is no current. Any clues? The speed setting appears to work as when it is set to zero, there is now power anywhere. No clicking relays, and when I turn it up they all click,

 

[Peter Relton]

Hi all,

So after lots of fiddling and following the advice given on the last thread, I thought I would start a new thread to explain where I'm at.

The motor still won't run. The main relay was burnt out so it has been replaced. The gas valve relay works. There is power to the torch. 38v on minimum and 68v on max. I have tested the motor off the machine on my car battery and it works. I have tested it in the machine with a car battery charger and it works. It appears there is no power coming out of the pcb. When I tested between terminal 2 on the pcb and the earth, or out of the motor there was no reading at all when the trigger is pulled. If I turn the speed dial to zero, there is no power anywhere. When I turn it up all the relays click and the torch reads but nothing from terminal 2. I can't see any obvious burning on the pcb. How do I test it?

Cheers.

 

[Peter Relton]

Hi all,

So after lots of fiddling and following the advice given on the last thread, I thought I would start a new thread to explain where I'm at.

The motor still won't run. The main relay was burnt out so it has been replaced. The gas valve relay works. There is power to the torch. 38v on minimum and 68v on max. I have tested the motor off the machine on my car battery and it works. I have tested it in the machine with a car battery charger and it works. It appears there is no power coming out of the pcb. When I tested between terminal 2 on the pcb and the earth, or out of the motor there was no reading at all when the trigger is pulled. If I turn the speed dial to zero, there is no power anywhere. When I turn it up all the relays click and the torch reads but nothing from terminal 2. I can't see any obvious burning on the pcb. How do I test it?

Cheers.

Stupidly, I forgot to add that the little green light on the pcb that sits between the speed and time control knobs isn't working.

 

[mike 109444]

Could be the transistor mounted to the heatsink that's duff. Follow the red dotted line which is the output to pin 2 of plug and you ill see it is the transistor that via the wire feed control pot supplies/controls power to the motor.

 

[Peter Relton]

Could be the transistor mounted to the heatsink that's duff. Follow the red dotted line which is the output to pin 2 of plug and you ill see it is the transistor that via the wire feed control pot supplies/controls power to the motor.

Thanks. Do I just check the continuity of that line or do I need the power on to check voltage?

 

[mike 109444]

If you clamp the neg side of your meter (black lead) to the work ground clamp. Set meter to DC volts up to say 50V (not sure what ranges your meter has). Make sure motor is connected. Then put meter read lead to the pin 1 of the 6 pin plug (black wire). Pull trigger and you should see a voltage of 15 to 30 ish depending on what power setting selected on welder. If good then move red lead to middle pin of transistor and again pull trigger and you should see same voltage as before. If ok then put red lead on left pin of transistor one with yellow dotted line again pull trigger and you should see a lower voltage depending on wire feed control position. This should be the low voltage control (< 10v ?) from the pot that controls the higher voltage that drives the motor. Think small signal controlling a large signal! If ok then move red probe to the right pin of transistor, red dotted line. Pull trigger and look for a 10 to 30v output. If ok then there may be a break in the wire from the pcb to the motor or the track. If not ok then transistor may be duff.

 

[mike 109444]

PS make sure the pcb does not short out while it is loose. Rest it on something insulated, even a piece of cardboard should do.

 

[Peter Relton]

If you clamp the neg side of your meter (black lead) to the work ground clamp. Set meter to DC volts up to say 50V (not sure what ranges your meter has). Make sure motor is connected. Then put meter read lead to the pin 1 of the 6 pin plug (black wire). Pull trigger and you should see a voltage of 15 to 30 ish depending on what power setting selected on welder. If good then move red lead to middle pin of transistor and again pull trigger and you should see same voltage as before. If ok then put red lead on left pin of transistor one with yellow dotted line again pull trigger and you should see a lower voltage depending on wire feed control position. This should be the low voltage control (< 10v ?) from the pot that controls the higher voltage that drives the motor. Think small signal controlling a large signal! If ok then move red probe to the right pin of transistor, red dotted line. Pull trigger and look for a 10 to 30v output. If ok then there may be a break in the wire from the pcb to the motor or the track. If not ok then transistor may be duff.

IT WORKS!!!!!! Now for the embarrassing bit. Thanks to your very detailed instructions and diagram on the pcb, I worked out the wires 2 and 5 were connected the wrong way. Depending on which side you are looking at the pcb they could be either. They were both blue at the connecting end for reasons I don't know as it is a second hand machine. Anyway, connected them correctly and away the motor went. It's all back together and I await spring and some gas to start work on my old Citroen CX. Just got to source the cheapest gas for a hobby welder! Thank you again for your very detailed and clear instructions. Without them I wouldn't have spotted the error.

Thanks again!

 

[mike 109444]

Well a result......