Purge button added to Lincoln SP125+

Greetings All, I posted in the Metalworking.com Dropbox a text file explaining the circuit changes to and the schematic of the Lincoln SP125 Plus welder
in order to add a gas purge button. The files begin with SP125+. I forgot to turn on word wrap in the text file so it has really long text lines. Oops. When viewing the tif file of the schematic using the viewing software to blow up the image will allow the schematic to be seen clearly enough to identify the areas mentioned in the text file. Anyway, the circuit changes allow the switching of low voltage by the added push button. This makes for a safer unit because the switching of the 125 volts to the gas solenoid itself is still done by the original factory circuitry. If you make these changes be sure to coat any areas of exposed circuit board and components with some type of non-conductive conformal coating similar to the factory applied coating to prevent shorts from any conductive dust that blows through the welder. I used clear 5 minute epoxy. Some silicone seal products use acetic acid in the formulation. They smell of vinegar. Don't use them because they can cause corrosion of metal inside the sealant. ERS
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@whidbey.com wrote:

Hey, Eric. What is the function of the "gas purge" button? You hit the button and the gas valve opens? Closes? You want to do preflow? Postflow?
Grant
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 01 May 2008 19:58:24 GMT, Grant Erwin
Greetings Grant, It's for pre-flow. The gas solenoid opens the valve and the gas flows making sure your weld has shielding gas from the start. Beats feeding wire and then clipping it off when you haven't welded for a few minutes. Eric

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I would just do what I do when I shut down the machine. Turn the speed to zero, and hit the trigger to expel gas in the hose and pressuring the regulator. It would work to preflow the gas, stop, then turn the wire speed to the right place, and trim about an inch or two of wire. Not much waste or time. But I never do anything, just fire it up and go. Guess I haven't welded anything that critical that I noticed any deficiencies at the start of the weld.
Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@whidbey.com wrote:

FYI here are the actual links:
http://metalworking.com/dropbox/SP125-_welder_circuit_changes_for_purge_button.txt http://metalworking.com/dropbox/SP125-_schematic.TIF
GWE
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.