Weldslayer
New Member
- Messages
- 6
- Location
- Canada, Southern Ontario
Hello, new here. I got stumped on a build and as I was scouring the internet for a solution I stumbled across this forum. Very Fortuitous.
Here goes;
I got an decent deal on a 1970's Idealarc 250. 250 amps @ 72 OCV. All it needed was a new cap for AC welding. I also bought it with the Intention of adding CV capability to it, using a spare control board from a 34 OCV 180 amp MIG welder. Silly, I know.
Diagram here. I'm fairly certain there is no diagram on the inside of Canadian machines. There are other folks who have these and don't have a diagram either. On the inside of my case has no old glue/outlines or a clean(er) spot where one might have been. I tried contacting Lincoln and they gave me the one for U.S. models. They are near identical except the primary windings are different. I altered it a bit to reflect the wiring for the primary connections when you run single phase 240v.
I used some heat conducting potting compound to attach a 60* Celsius T-stat switch to the secondary that is connected to the SSR that allows power to flow through the contact side and energize the transformer. The idea is is that once the transformer heats up to 60 degrees the torch/stinger goes dead until it cools again. From there you can either activate the CC SSR or the CV SSR using the CC/CV switch.
Turning on the CC SSR will disconnect the primary going to the board, and the 500a solenoid for one of the secondary leads going to the CV Rectifier so the caps don't charge and the voltage is no longer being regulated. It will also cut power to the CV SSR and disconnect the primary going to the board. The CC SSR will open allowing H3 and H5 complete the circuit back to the switch. I have no time delay circuit for the 500a solenoid integrated yet - I've been shutting the machine off and then switching to CV/CC so I don't weld the contacts on the 500a solenoid together.
Switching to CV, the CC SSR will deactivate and the CV SSR will activate and let power from the primary through to the board at B1/B2, activate the 12v relay to let J2-3 have its 120v supply and activate the 500 solenoid to connect the secondary to the CV rectifier.
Afterwards it was just a matter of hooking up the board connections (trigger,Voltage sense, voltage control wires), plugging in the feeder and cranking the amperage wheel to max. Adjust wire feed speed and voltage as normal. Simple magic, or so I thought.
Now this is about where I realized I was in deep water. After fighting with the wiring on the 25k pot for an evening I figured trying to tame 66vdc at the rectifier with that little board is unrealistic. No matter how I had that pot hooked up it or what resistors I added - It would behave erratically. I couldn't get it to dial consistently or limit it to a range of 15 to 40v. When I gave up, I had managed to get it set to 24v but I could only weld about an inch before tripping the 25a overload for the board. At least I had the Caps wired with the right polarity .
[Actually welded pretty decent and smoothly. You can see where the wire stubbed into the puddles when the overload tripped. Fairly high crown but I Figured that was because I was using C25 and a inductance choke meant for straight co2]
The PCB is meant to regulate voltage from 14ish to 34v. I think I was a little over-optimistic when I thought I could use it with this build. I've been reading up on voltage regulation and the ways to accomplish it but it remains unclear to me what the best solution would be.
So taking into consideration the goal is to be able to regulate the voltage to 15v to 40v and limit the voltage on the CV side of things to 40v max,
1- Is there off the shelf components I can use to accomplish this? Maybe an outfit that can do a custom circuit for me?
2 - Should I be considering a controlled rectifier with transistor/thyristors? Regulate the primary? I also don't understand the pros and cons to each and I would like to use whats most optimal. Also a variac is out because it would just be too bulky to fit anywhere and I don't really want to make the machine weigh too much more. Just wondering what would be the best way to do this and if anyone has any suggestions?
I managed to score the board diagram if that helps.
And here's the one for the welder it goes with.
Any advice would be greatly appreciated. Thank you for reading.
Here goes;
I got an decent deal on a 1970's Idealarc 250. 250 amps @ 72 OCV. All it needed was a new cap for AC welding. I also bought it with the Intention of adding CV capability to it, using a spare control board from a 34 OCV 180 amp MIG welder. Silly, I know.
Diagram here. I'm fairly certain there is no diagram on the inside of Canadian machines. There are other folks who have these and don't have a diagram either. On the inside of my case has no old glue/outlines or a clean(er) spot where one might have been. I tried contacting Lincoln and they gave me the one for U.S. models. They are near identical except the primary windings are different. I altered it a bit to reflect the wiring for the primary connections when you run single phase 240v.
I used some heat conducting potting compound to attach a 60* Celsius T-stat switch to the secondary that is connected to the SSR that allows power to flow through the contact side and energize the transformer. The idea is is that once the transformer heats up to 60 degrees the torch/stinger goes dead until it cools again. From there you can either activate the CC SSR or the CV SSR using the CC/CV switch.
Turning on the CC SSR will disconnect the primary going to the board, and the 500a solenoid for one of the secondary leads going to the CV Rectifier so the caps don't charge and the voltage is no longer being regulated. It will also cut power to the CV SSR and disconnect the primary going to the board. The CC SSR will open allowing H3 and H5 complete the circuit back to the switch. I have no time delay circuit for the 500a solenoid integrated yet - I've been shutting the machine off and then switching to CV/CC so I don't weld the contacts on the 500a solenoid together.
Switching to CV, the CC SSR will deactivate and the CV SSR will activate and let power from the primary through to the board at B1/B2, activate the 12v relay to let J2-3 have its 120v supply and activate the 500 solenoid to connect the secondary to the CV rectifier.
Afterwards it was just a matter of hooking up the board connections (trigger,Voltage sense, voltage control wires), plugging in the feeder and cranking the amperage wheel to max. Adjust wire feed speed and voltage as normal. Simple magic, or so I thought.
Now this is about where I realized I was in deep water. After fighting with the wiring on the 25k pot for an evening I figured trying to tame 66vdc at the rectifier with that little board is unrealistic. No matter how I had that pot hooked up it or what resistors I added - It would behave erratically. I couldn't get it to dial consistently or limit it to a range of 15 to 40v. When I gave up, I had managed to get it set to 24v but I could only weld about an inch before tripping the 25a overload for the board. At least I had the Caps wired with the right polarity .
[Actually welded pretty decent and smoothly. You can see where the wire stubbed into the puddles when the overload tripped. Fairly high crown but I Figured that was because I was using C25 and a inductance choke meant for straight co2]
The PCB is meant to regulate voltage from 14ish to 34v. I think I was a little over-optimistic when I thought I could use it with this build. I've been reading up on voltage regulation and the ways to accomplish it but it remains unclear to me what the best solution would be.
So taking into consideration the goal is to be able to regulate the voltage to 15v to 40v and limit the voltage on the CV side of things to 40v max,
1- Is there off the shelf components I can use to accomplish this? Maybe an outfit that can do a custom circuit for me?
2 - Should I be considering a controlled rectifier with transistor/thyristors? Regulate the primary? I also don't understand the pros and cons to each and I would like to use whats most optimal. Also a variac is out because it would just be too bulky to fit anywhere and I don't really want to make the machine weigh too much more. Just wondering what would be the best way to do this and if anyone has any suggestions?
I managed to score the board diagram if that helps.
And here's the one for the welder it goes with.
Any advice would be greatly appreciated. Thank you for reading.