Mig Welder-Wire Feed Motor 24v Power Supply Not Working-Requesting Assistance - Page 1
Forum section: electronics / repair

author: SLIK
author_rank: Newbie
timestamp: July 21, 2024, 04:43:02 pm
content: Hi,I e-mailed Dave about this, he kindly directed me to the forum.Quick summary: Expensive near new welder broke. Trying to repair. Please help. I have come a gutzer!I had purchased a Fronius TransSteel watercooled 500A mig welder in 2016. (I'm not an electrician)Brand new they cost around $12,000USD, but i paid $6,000 for a lightly used demo unit.I didn't have access to 3ph power until earlier this year, so I didn't use the welder for about 7 years.I put in a 60A breaker on the 230v, and it seemed to be working properly for about 4-5 hours, throughout 1 week.The problem i am having seems to be the 24v wire feed motor power supply section of the main power source board. This board is not available for purchase, and the price is about $2,500.I figured i have not much to lose, so i opted to troubleshoot/repair it myself.I also found a crushed wire that supplies 24v to the main cooling fan, sandwiched between a screw and the chassis/frame, the insulation was shredded, possibly shorting to ground. It came from the factory like this. I have repaired that wire.I found a burnt 0204 melf resistor, but could not confirm it's value.Despite being burnt to a crisp, it measured 1k ohms, but it was placed in series with 5 other 470 ohm resistors.I carefully soldiered a 1k ohm resistor in it's place, and LED's on the board that did not light up before, now lit up red, which i believe indicates some error is detected at that location of the circuit.Other LED's on the board light up green.When testing the welder, it feeds wire very slowly now, maybe 5% of normal speed, so i tried a 470 ohm resistor and had the same result.My next step is to use an LCR meter to validate the nearby capacitors.After that i will try to test other components such as diodes.I am reaching the extent of my understanding of this circuitry.I tried to reach out to Fronius support several times but it is out of warranty, so the next step would be to contact you to beg for help.If you would consider taking a look at this, i would greatly appreciate any suggestions.I have attached a few pictures.

author: Poroit
author_rank: Frequent Contributor
timestamp: July 22, 2024, 04:30:01 am
content: Be careful working on that thing when it is alive.Can you see the Voltage and Current ratings on the Wire Feed Motor?If you have a suitable Bench Top power supply, I would check the motor first.Prove that and then focus on the PCB.BTWI thought "Gutzer" was an Australian colloquial term.....I did not know it was used in the USA.

author: beatman
author_rank: Regular Contributor
timestamp: July 22, 2024, 12:39:40 pm
content: check all so the 47n Y2 capacitor.

author: coppercone2
author_rank: Super Contributor
timestamp: July 22, 2024, 12:52:27 pm
content: what is it supposed to do, PWM the motor or vary voltage to regulate speed?

author: CaptainBucko
author_rank: Regular Contributor
timestamp: July 23, 2024, 12:56:26 am
content: Wire feed speed on most MIG welders is normally driven from a voltage sourced from a potentiometer. Not sure how it works in this unit, but check that the wire speed control pot is correctly connected to the main unit.