I am currently trying to replace the heat selector switch in a Silver Beauty 90100 that is my nephews. He took the old switch out and when we took it apart it exploded. No idea how the contacts and cams were configured. Does anyone here know how the switching on the primary side of the transformer is done. There are three coils on the primary and looking at the schematic coil #1 is hooked in series with coil #2 (R4 and R3) and coil #3 is in series with coil #2 (R3 and R2). Assuming R1 is common, I can see three taps for switching, R2, R3 and R4. This welder is supposed to have four settings plus off (5 positions). Hopefully someone here has done this and can advise how this sequence works. Thanks. Jack
I haven't worked on one, but it sure looks like a strange (unconventional) wiring diagram.
From what I've gathered, it looks like it was made by an Italian company called Telwin and distributed in the US by Triple-A Specialty Co. in Chicago. https://weldingdirect.com/sibeto.html
Have you tried to contact the manufacturer? Maybe weldingdirect could give you a lead.
Thank you Denis. I'll see what information I can get from Triple-A.
From your attached pdf, I assume that you measured each of the three primary coils with an ohmmeter. Are the wires on the primary tapped from a single winding or are there 3 individual coils on the primary? If you have 3 individual coils, you could combine them to have more voltage choices with your selector.
Usually you get a better idea of number of turns on each primary coil using an LCR meter (if you have one) measuring with the secondary disconnected.
There are three individual coils. I don't have an LCR meter (have a fluke 15B+ and fluke 77, I don't think either measures inductance.) They way it was originally hooked up was with coils in series. Would you suggest any combinations? Thanks.
There are three individual coils. I don't have an LCR meter (have a fluke 15B+ and fluke 77, I don't think either measures inductance.) They way it was originally hooked up was with coils in series. Would you suggest any combinations? Thanks.
I was thinking that if the coils had different impedances, you might be able to combine them in a way to get different mid-range voltages. If you have coils C1, C2 and C3 and they have different impedances, then C1+C2 would be different than C2+C3. If the coils had all equal values, then it wouldn't matter.
Denis, Using a LCR meter I get the following: C1 = .485mH; C2 = 43.6mH; C3 = 1.94mH. What do you think? These measurements are made with the rectifier still connected. Do I need to disconnect it and remeasure? Note: Coil 1 and Coil 2 were connected in series and Coil 2 and Coil 3 also as factory default.
Denis, Using a LCR meter I get the following: C1 = .485mH; C2 = 43.6mH; C3 = 1.94mH. What do you think? These measurements are made with the rectifier still connected. Do I need to disconnect it and remeasure? Note: Coil 1 and Coil 2 were connected in series and Coil 2 and Coil 3 also as factory default.
I think it's better with the rectifier disconnected. Whatever reading you get will be relative measurements.
I thought of another approach. If you have a 24VAC doorbell transformer, you could hook that up to the secondary side to supply the secondary with voltage (with the rectifier disconnected). Then measure the primary side and see what AC voltages you get. That would also tell you the relative differences in the coils and how to set up a new selector switch. The voltages should be stepped up, but the power should be limited by the power applied by the bell transformer.
I think it's better with the rectifier disconnected. Whatever reading you get will be relative measurements.
I thought of another approach. If you have a 24VAC doorbell transformer, you could hook that up to the secondary side to supply the secondary with voltage (with the rectifier disconnected). Then measure the primary side and see what AC voltages you get. That would also tell you the relative differences in the coils and how to set up a new selector switch. The voltages should be stepped up, but the power should be limited by the power applied by the bell transformer.
That make sense. I'll give it a try tomorrow and let you know what the results are.
That make sense. I'll give it a try tomorrow and let you know what the results are.
The secondary might have really low impedance so I'd watch out how long the doorbell transformer is attached. It might burn up if left too long. As long as you can make ratios of the voltages, it should predict what you get when it's connected correctly.
Voltage in = 19.7 vac. Coil 1/2 = 7.64 vac. Coil 3/4 = 74.0 vac. Coil 5/6 = 15.3 vac. With 19.7 vac in secondary, I jumped wire 2&3 and 4&5 with output across 1 & 6 and got 96.5 vac. With secondary unhooked I got the following inductance reading:
1 - 2 (coil 1) = .52mH; 3 - 4 (coil 2) = 45.5mH and 5 - 6 (coil 3) = 2.1mH. Secondary coil = 77.9mH.
Hmmm. I'm not sure why the secondary has a higher inductance than the primary. Seems like it should be lower for a step-down transformer.
Does the LCR meter tell you the frequency at which the inductance was measured? Maybe the frequency got switched for that reading? They should all be measured at the same frequency.
(Another thought - could you have been measuring the secondary coil that supplies the wire feed motor and not the welding output?)
From the voltages you got I would guess the selector might be set up like this:
Position 0 = Off
Position 1 = Coil 1 + Coil 2 + Coil 3 (lowest output voltage)
Position 2 = Coil 2 + Coil 3
Position 3 = Coil 2 + Coil 1
Position 4 = Coil 2 (highest output voltage)
Is this MIG set up for 120 or 240VAC? Another thing to check is the gauge of wire on the primary side of the transformer.
Hmmm. I'm not sure why the secondary has a higher inductance than the primary. Seems like it should be lower for a step-down transformer.
Does the LCR meter tell you the frequency at which the inductance was measured? Maybe the frequency got switched for that reading? They should all be measured at the same frequency.
(Another thought - could you have been measuring the secondary coil that supplies the wire feed motor and not the welding output?)
From the voltages you got I would guess the selector might be set up like this:
Position 0 = Off
Position 1 = Coil 1 + Coil 2 + Coil 3 (lowest output voltage)
Position 2 = Coil 2 + Coil 3
Position 3 = Coil 2 + Coil 1
Position 4 = Coil 2 (highest output voltage)
Is this MIG set up for 120 or 240VAC? Another thing to check is the gauge of wire on the primary side of the transformer.
Sorry, the 77.9mH was the total of all three primary coils in series. Secondary is 3.16mH. I'll give your setup a try, I think I see where this is going now. I'll let you know. Probably take a day or two. Thanks. Oh, the setup is 120VAC.
Sorry, the 77.9mH was the total of all three primary coils in series. Secondary is 3.16mH. I'll give your setup a try, I think I see where this is going now. I'll let you know. Probably take a day or two. Thanks. Oh, the setup is 120VAC.
From calculating the impedance, I think that there's something wrong with the center coil (#2). For 60 Hz, the impedance is about 17.2 ohms, so that would limit the current to about 7 amps for 120 V. Doesn't seem right for a welder.
Denis, I completed the hookup as per our communications and presented the welder to my nephew (owner) to try out. He tried it out on several settings and was happy with it. He made the comment that the low setting seemed a little hotter than original and the highest setting didn't seem as hot as original. I am attaching a drawing of the completed unit.
Nice schematic! Much better than what was supplied in the manual for that welder. I think that it was some cross between a block diagram and a true circuit diagram.
How did you solve the busted selector switch? Were you able to glue it back together or did you replace it?
Thank you. The original switch was a Bremas cam switch. Like everyone else on here, I started taking it apart and it exploded with springs and contacts flying everywhere. No way of putting it back together. The old Bremas switch was obsolete and I figured that it was a switch made for the welder's manufacturer since the newer switchs didn't match what I needed. I tried to figure out a way to wire it using a low voltage selector switch to switch on a series of relays. Didn't have enough room inside the cabinet for them so I started looking at the alternatives and came up with the Baomain rotary cam switch P/N SZW26-20/0-4.4. It's only rated at 20A and I'm hoping that will handle what is needed. The chart at the upper left side of my drawing is the switching sequence of the switch. I noted that several years ago there was a lot of chatter on this site talking about replacing the switch and I hope anyone that didn't complete their repair might see this. I got the switch from Amazon for $10.89. Not bad if it holds up. Again I thank you as you have been the missing link in getting this job completed. I'll be signing off now and be back from time to time to check on things.
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Originally Posted by venthead
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