Fan On Demand

I have a Miller Syncrowave 350 TIG welder that has served me well since 1992
, I do a lot of very light work with the unit that would not require the fan
to run , probably 98 % of my welding is tiny and aircraft type work.
Contacted Miller to see if they had a Retro Fit kit for the unit as the new
ones have [ FAN ON DEMAND } , Miller says no dice , would seem logical to
have such thing , but no. Could go on my own and put a couple sensors ,
relay etc. , hate to damage rect. etc. , wonder if anybody has ever made
this mod. to an older 350 , main problem with Fan is the noise and dust
.Thanks Phil , Middlefield , Ohio
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Miller isn't about to Ok such a retrofit without doing a careful thermal design review. That's expensive, and not worth their time for an older machine. So you're on your own, and any liability due to your retrofit is on your shoulders.
The problem is that even if you thermally bond sensors to the heatsink and transformer, other parts of the circuit may get enough conducted, convected, or radiated heat to be damaged before the sensors call for the fan to run. In other words, even though you might protect the diodes and transformer, you might inadvertently cook the control board because it expects a certain continuous flow of cooling air.
Me, I'd let the fan run. But do what you like. It is your welder, and your nickel.
Reply to
Gary Coffman
You could always wire in a switch that you could control manually when you feel it needs some cooling
Reply to
Be very cautious in changing a design. Liability laws might be re-flecked on to you.
There is something called thermal resistance. Theta J(parameter). It is used in semiconductor cooling and other heat sink concepts.
The thermal resistance (just like ohms law) can be high enough that if the sinking (fan) isn't there, the core would overheat long before an outside sensor can see it.
Reply to
Martin H. Eastburn
After years of Miller Bobcats & Bluestars and shop stick machines my very first MIG setup was a Century (rue that day) but I put a sensor in the line for fan on demand and it worked great! I think I used a point of 125F for contact. But since anything Century makes is crap .... in our shop with 5 machines "if it ain't BLUE it won't do!
Reply to
Check the duty cycle of the machine to see how long you may weld at a higher current. The machine should automatically cut off before you can do any damage to the rectifiers.
Reply to
Harry Culshaw

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