I have a snap on 2135 mig that ive been using for about 10 years, just recently switching to full power makes no difference to the weld, ive taken the side off the machine incase there were any loose wires etc but no such luck. Has anyone else experienced this?
- Thread starter E30Dan
- Start date
Ive tested the switches today and they are both fine, swapped them round too for good measure.
Did some testing with a voltmeter across the two aluminium plates, switched to Pos 1 im getting 35v which drops to 21v when welding, switched to position 2 im getting 40v which drops to 23v when welding
Does that sound about right? there is no noticeable difference in the weld
Did some testing with a voltmeter across the two aluminium plates, switched to Pos 1 im getting 35v which drops to 21v when welding, switched to position 2 im getting 40v which drops to 23v when welding
Does that sound about right? there is no noticeable difference in the weld
NotANormalCoder
Retired fixer of welders
- Messages
- 315
- Location
- Surbiton - Surrey -UK
Best guess is that you have a failed diode in the rectifier (the two ally plates you referrred to). Visually inspect the individual diodes. There are small 'tails' that go from the pressed into the ally plate part, to other parts of the assembly. You are looking for either a broken tail or evidence of burning. It is not always obvious which diode or diodes have failed, as they can fail short or open circuit and you will only see broken tails if they fail short circuit. Both types of failure result in power loss. These diodes are almost impossible to replace, even though they are sometimes available. Best idea is to replace the whole unit. Note - Before disconnecting any wires from the rectifier, be absolutely sure that you know which connections are for AC input (often marked with a squiggle and will come from the main welding transformer) and which connections are DC positive and negative (will go to welding torch and earth respectively). Take pictures, mark wires and be certain. Replacing the rectifier with the wrong connections will result in more damage!
Dave
Dave
Thanks Dave, I found this guide and as you say I would guess I have an open circuit diode which results in loss of power
http://www.instructables.com/id/Mig-Welder-upgrade-diode-replacement-in-bridge-rec/
So will now look for some upgraded diodes, as it has to come to bits I may as well upgrade it if possible
http://www.instructables.com/id/Mig-Welder-upgrade-diode-replacement-in-bridge-rec/
So will now look for some upgraded diodes, as it has to come to bits I may as well upgrade it if possible
I've now removed the rectifier and done some tests on the diodes, as much as I can as they seem to work in pairs, a couple look like they have some heat damage, they all appear to work properly, reading in one direction and nothing in the other, these are the numbers I got from each
549 549 559 560
547 547 550 550
So all seems ok here?
549 549 559 560
547 547 550 550
So all seems ok here?
NotANormalCoder
Retired fixer of welders
- Messages
- 315
- Location
- Surbiton - Surrey -UK
One or two of those seem a bit iffy to me. Shorted diodes will meter as a short but any open circuit diodes will not show up, as 2 are wired in parallel and the good one will give you a good reading. The only way to accurately check is to seperate and measure each individual diode. I do not recommend this as you will certainly damage some diodes in the process and then you are back to square one. If you can source a replacement, I think you should replace the complete unit. Remember to accurately note the polarity(+ve , -ve and AC) and location of every wire you take off.
I have tried many times to fix these rectifiers and it always results in grief!
Dave
I have tried many times to fix these rectifiers and it always results in grief!
Dave
