I've got this thing a few years ago and had messed with it some but was unsatisfied for the most part. It wasn't until I ditched the plastic liner for a metal one that it started working more like the lincolns at school. After some digging I realized that it was a precursor to the chinese migs that are rebranded by many companies including 'chicago electric' and quite possibly SIP.
I did some more digging and figured that the dual mig 171 which has identical specs was perhaps the same unit (w/gasless capability and a few improvements). Further investigation revealed that cemont makes an 'easymig 171' which has an identical schematic to the Harbor Freight 171.
I opted to change the power chord for a 30 amp dryer unit w/a Nema 50 amp plug and ordered a pancake fan following the 151 thread in the weldingweb forum. After going through some links on here I discovered that ppl were making a dedicated power supply for the feed motor, and it's at this stage where i've hit a roadblock.
From my limited understanding of electronics, I figured that the mod in the weldingweb forum involves tapping from the transformer and providing an additional rectifier for the dc motor, unlike the mods here which involves a dedicated transformer (rectified) feeding from the power chord. Additionally a resistor is used at weldingweb to unload the smoothing cap, while you guys seem to use a relay to brake the motor.
Where I'm confused is whether the power supply (be it piggybacking or dedicated) feeds the control board which then does its magic to regulate the speed of the motor or if this board is somehow bypassed.
So the plan as it stands is as follows:
1.Fan mod.
2.Improve feed motor, be it by dedicated or piggyback ps.
3.smoothing capacitor (with emphasis on retaining thin metal capability).
4. Tweco style quick disconnect torch retrofit perhaps (OEM unit has the mechanical unit molded as part of the handle; really a very compromising concept).
5. Add gasless capability (is it as simple as making jumper/posts to switch torch/ground polarity?
As of now, I'm leaning towards the mod on here, mostly due to the fact that I found a dedicated transformer power supply (w/240V to 24 vdc) and also from observing that cemont decided to include an extra transformer in their newer units for what seems to me this same purpose.
Attached are a series of pictures of the board (could not find a contactor anywhere, but a Triac was on board) along with some 'nudies' of the machine and the schematics of the 171 and the one with an extra trans.
this is the more expensive cemont welder w/the extra transformer and contactor. I'd love to be able to implement that part of the circuit in my machine if it somehow improves performance
I did some more digging and figured that the dual mig 171 which has identical specs was perhaps the same unit (w/gasless capability and a few improvements). Further investigation revealed that cemont makes an 'easymig 171' which has an identical schematic to the Harbor Freight 171.
I opted to change the power chord for a 30 amp dryer unit w/a Nema 50 amp plug and ordered a pancake fan following the 151 thread in the weldingweb forum. After going through some links on here I discovered that ppl were making a dedicated power supply for the feed motor, and it's at this stage where i've hit a roadblock.
From my limited understanding of electronics, I figured that the mod in the weldingweb forum involves tapping from the transformer and providing an additional rectifier for the dc motor, unlike the mods here which involves a dedicated transformer (rectified) feeding from the power chord. Additionally a resistor is used at weldingweb to unload the smoothing cap, while you guys seem to use a relay to brake the motor.
Where I'm confused is whether the power supply (be it piggybacking or dedicated) feeds the control board which then does its magic to regulate the speed of the motor or if this board is somehow bypassed.
So the plan as it stands is as follows:
1.Fan mod.
2.Improve feed motor, be it by dedicated or piggyback ps.
3.smoothing capacitor (with emphasis on retaining thin metal capability).
4. Tweco style quick disconnect torch retrofit perhaps (OEM unit has the mechanical unit molded as part of the handle; really a very compromising concept).
5. Add gasless capability (is it as simple as making jumper/posts to switch torch/ground polarity?
As of now, I'm leaning towards the mod on here, mostly due to the fact that I found a dedicated transformer power supply (w/240V to 24 vdc) and also from observing that cemont decided to include an extra transformer in their newer units for what seems to me this same purpose.
Attached are a series of pictures of the board (could not find a contactor anywhere, but a Triac was on board) along with some 'nudies' of the machine and the schematics of the 171 and the one with an extra trans.
this is the more expensive cemont welder w/the extra transformer and contactor. I'd love to be able to implement that part of the circuit in my machine if it somehow improves performance