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Posted by on April 29, 2008, 10:06 pm
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Greetings All,
I haven't posted or read any newsgroups for a long time. I am still
finishing up my house and it has been really all consuming. Anyway, I
know that there are a few folks here who have a Lincoln SP125 Plus
welder. I added a purge button to mine a while ago and it is a big
help. Saves wire and time. It would have been simple to use just a
switch to actuate the gas solenoid but the solenoid is a 125 volt unit
and I wanted to only switch low voltage. So instead I figured out how
to use the low voltage circuitry that the welder uses. I'm sure that
there is a better way but since my knowledge of electronics is so
limited it is what it is. I sent the circuit changes and the scanned
schematic to the dropbox a few minutes ago. Look for files beginning
with SP125+. After I made the changes I coated the circuit board with
epoxy in the areas where I had to remove the conformal coating. It's
important to prevent any conductive dust from shorting anything. I
hope this is useful to someone. Please feel free to tell me how it
could have been done better.
Cheers,
Eric R Snow
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Posted by Don Foreman on April 30, 2008, 12:50 am
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On Wed, 30 Apr 2008 02:06:44 GMT, etpm@whidbey.com wrote:
>Greetings All,
>I haven't posted or read any newsgroups for a long time. I am still
>finishing up my house and it has been really all consuming. Anyway, I
>know that there are a few folks here who have a Lincoln SP125 Plus
>welder. I added a purge button to mine a while ago and it is a big
>help. Saves wire and time. It would have been simple to use just a
>switch to actuate the gas solenoid but the solenoid is a 125 volt unit
>and I wanted to only switch low voltage. So instead I figured out how
>to use the low voltage circuitry that the welder uses. I'm sure that
>there is a better way but since my knowledge of electronics is so
>limited it is what it is. I sent the circuit changes and the scanned
>schematic to the dropbox a few minutes ago. Look for files beginning
>with SP125+. After I made the changes I coated the circuit board with
>epoxy in the areas where I had to remove the conformal coating. It's
>important to prevent any conductive dust from shorting anything. I
>hope this is useful to someone. Please feel free to tell me how it
>could have been done better.
>Cheers,
>Eric R Snow
They may not have arrived yet.
You may get lots of advice about how you could have done it better --
most from those who haven't done it at all. I sure won't argue with
"done" and "works"!
Good move re-coating areas from which you removed conformal coating.
For future reference: epoxy can cause problems but you'd know it by
now if you had a problem. A more compliant material like a urethane
or silicone may place less post-cure mechanical stress on potted or
coated electronic parts. That said, I've used plenty of epoxy without
any problems.
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Posted by on April 30, 2008, 2:19 pm
Please log in for more thread options On Tue, 29 Apr 2008 23:50:44 -0500, Don Foreman
Greetings Don,
I didn't know epoxy would pull when curing. Thanks for the heads up. I
thought about silicone but all I had on hand was the stuff with acetic
acid in it and it corrodes stuff while curing sometimes.
ERS
>On Wed, 30 Apr 2008 02:06:44 GMT, etpm@whidbey.com wrote:
>
>>Greetings All,
>>I haven't posted or read any newsgroups for a long time. I am still
>>finishing up my house and it has been really all consuming. Anyway, I
>>know that there are a few folks here who have a Lincoln SP125 Plus
>>welder. I added a purge button to mine a while ago and it is a big
>>help. Saves wire and time. It would have been simple to use just a
>>switch to actuate the gas solenoid but the solenoid is a 125 volt unit
>>and I wanted to only switch low voltage. So instead I figured out how
>>to use the low voltage circuitry that the welder uses. I'm sure that
>>there is a better way but since my knowledge of electronics is so
>>limited it is what it is. I sent the circuit changes and the scanned
>>schematic to the dropbox a few minutes ago. Look for files beginning
>>with SP125+. After I made the changes I coated the circuit board with
>>epoxy in the areas where I had to remove the conformal coating. It's
>>important to prevent any conductive dust from shorting anything. I
>>hope this is useful to someone. Please feel free to tell me how it
>>could have been done better.
>>Cheers,
>>Eric R Snow
>
>They may not have arrived yet.
>
>You may get lots of advice about how you could have done it better --
>most from those who haven't done it at all. I sure won't argue with
>"done" and "works"!
>
>Good move re-coating areas from which you removed conformal coating.
>For future reference: epoxy can cause problems but you'd know it by
>now if you had a problem. A more compliant material like a urethane
>or silicone may place less post-cure mechanical stress on potted or
>coated electronic parts. That said, I've used plenty of epoxy without
>any problems.
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Posted by Brian Lawson on April 30, 2008, 2:07 am
Please log in for more thread options Hey Eric,
Nice to see your name again. It has been some time!! I do understand
the bit about "the house" though. Welcome to the club!!
Regards your drop-box submission, I get the text up OK, but the TIF
seems empty.
I have a similar MIG, and just wonder what the purpose of your mod is.
Purge? I always think that is a way to clear former gases, but maybe
you are suggesting that you fill the torch line with pressure prior to
the arc starting the gas flow. Is that it?
Take care.
Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXX
On Wed, 30 Apr 2008 02:06:44 GMT, etpm@whidbey.com wrote:
>Greetings All,
>I haven't posted or read any newsgroups for a long time. I am still
>finishing up my house and it has been really all consuming. Anyway, I
>know that there are a few folks here who have a Lincoln SP125 Plus
>welder. I added a purge button to mine a while ago and it is a big
>help. Saves wire and time. It would have been simple to use just a
>switch to actuate the gas solenoid but the solenoid is a 125 volt unit
>and I wanted to only switch low voltage. So instead I figured out how
>to use the low voltage circuitry that the welder uses. I'm sure that
>there is a better way but since my knowledge of electronics is so
>limited it is what it is. I sent the circuit changes and the scanned
>schematic to the dropbox a few minutes ago. Look for files beginning
>with SP125+. After I made the changes I coated the circuit board with
>epoxy in the areas where I had to remove the conformal coating. It's
>important to prevent any conductive dust from shorting anything. I
>hope this is useful to someone. Please feel free to tell me how it
>could have been done better.
>Cheers,
>Eric R Snow
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Posted by Karl Townsend on April 30, 2008, 6:40 am
Please log in for more thread options
> I have a similar MIG, and just wonder what the purpose of your mod is.
> Purge? I always think that is a way to clear former gases, but maybe
> you are suggesting that you fill the torch line with pressure prior to
> the arc starting the gas flow. Is that it?
Sounds like Eric has the solution to a problem I just live with. If you set
the MIG gun down for more than a short break, the first bit of welding will
just burn up and look like chicken s^&*. I guess there's a reason for
shielding gas.
Karl
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>I haven't posted or read any newsgroups for a long time. I am still
>finishing up my house and it has been really all consuming. Anyway, I
>know that there are a few folks here who have a Lincoln SP125 Plus
>welder. I added a purge button to mine a while ago and it is a big
>help. Saves wire and time. It would have been simple to use just a
>switch to actuate the gas solenoid but the solenoid is a 125 volt unit
>and I wanted to only switch low voltage. So instead I figured out how
>to use the low voltage circuitry that the welder uses. I'm sure that
>there is a better way but since my knowledge of electronics is so
>limited it is what it is. I sent the circuit changes and the scanned
>schematic to the dropbox a few minutes ago. Look for files beginning
>with SP125+. After I made the changes I coated the circuit board with
>epoxy in the areas where I had to remove the conformal coating. It's
>important to prevent any conductive dust from shorting anything. I
>hope this is useful to someone. Please feel free to tell me how it
>could have been done better.
>Cheers,
>Eric R Snow