Inverter Welder Repair - Page 1
Forum section: electronics / repair

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 02:26:20 am
content: Hello I'm new on this site need some help with an inverter welder which I am trying to fix.I have a repair manual for it but can't seem to find a transformer replacement for it.Was wondering if anyone could advise me on what transformer I would need judging from the schematic that I've attached.The Transformer is marked TR2 (M26127 C4209).Thanks in advance.

author: xavier60
author_rank: Super Contributor
timestamp: June 18, 2020, 02:34:40 am
content: It's more likely that the SMPS IC has failed. Check all of the diodes first.Be certain that the large capacitors are fully discharged before working on it.

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 02:40:21 am
content: Hiya thanks for the reply I checked all the diodes and changed out the fried ones still didn't work so I pulled out the transformer and on the primary side it has no reading.I even tested it with the power on checked to see if there was any voltage coming from the output side of the transformer nothing at all

author: xavier60
author_rank: Super Contributor
timestamp: June 18, 2020, 03:17:32 am
content: I did a search on "Welder Auxiliary Power Transformer" and found many. But one has to be matched to the original with high certainty.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 18, 2020, 05:38:52 am
content: Quote from: WelderCrafts on June 18, 2020, 02:40:21 amDoes that mean you ran a couple of wires and a mains plug to the primary?

author: xavier60
author_rank: Super Contributor
timestamp: June 18, 2020, 06:15:54 am
content: Quote from: WelderCrafts on June 18, 2020, 02:40:21 amIt seems really odd that there would be faulty diodes and open primary.Which diodes were faulty and in which way did they fail?

author: George Edmonds
author_rank: Frequent Contributor
timestamp: June 18, 2020, 06:17:32 am
content: HiFrom the looks of it this is the low voltage power supply, can you show the entire power supply drawing.It is unusual for SMPSU transformers to go open circuit they usually fail with shorted turns.George G6HIG

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 11:33:24 am
content: I did the testing while the transformer was still on the board

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 11:39:13 am
content: I attached the pdf of the welder mines the one with the 3 big capacitors.Might have to scroll down abit.Appreciate all your help

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 12:21:22 pm
content: Quote from: xavier60 on June 18, 2020, 06:15:54 amI highlighted the diodes that failed and the one capacitor.They are all in line with viper IC.Only problem is that I'm not too sure on how to test ICs so I have no clue whether it's fried or not.

author: xavier60
author_rank: Super Contributor
timestamp: June 18, 2020, 12:39:30 pm
content: Damage to those parts should mean damage to others like T2 also.Seems the original cause should be IC2 having broken down, drawing large fault current through the primary, also spiking components connected to it.But usually these small SMPS IC blow their tops in an obvious way.You can check for pins that are short to ground although they can just as likely to be open.One certainty will be from checking for the presence of the internal MOSFET's body diode.

author: WelderCrafts
author_rank: Newbie
timestamp: June 18, 2020, 01:14:42 pm
content: Quote from: xavier60 on June 18, 2020, 12:39:30 pm.I changed out all the mosfets as I thought that was the problem at first but after testing still didn't work then I tested the viper circuit looked like it wasn't getting any power.upon examining the transformer I noticed a a burn mark on the bottom side which led me to think it was defective I removed it from the board and did a resistance test and indeed it is defective.Going to try find a replacement and change out the viper IC and see how it goes from there.Really appreciate all the helpThank you so much