Need help trouble shooting welder

Thread Starter

Adam halcom

Joined May 7, 2017
22
I purchased a welder over a year ago and haven't been able to use it due to it pops a fuse inside the welder. I have a ladder drawing but honestly I don't really understand all the ins and outs. It has one single layer PCB and honestly have no knowledge on how to check it. I can post the print for the welder. I would greatly appreciate any help because buying a new welder is not a option at this time. The machine is a old Linde ucc 305.
 

Thread Starter

Adam halcom

Joined May 7, 2017
22
I have a risistance ribbon that will heat up to at least 300 degrees. Rung 71 has a DC check point that should show a variable rang my is constant no matter the postion on the pot. I have replaced the pot to rule it out. If the blue wire is unplugged on line 60 at tpi 1the resistant ribbon will not heat up the step down transformer is good. So my thought is a screenshot could be bad that is on heat sink 2 or there is a short in the board. If the board is removed from the welder it will not heat up the ribbon or blow a fuse. Hope this isn't too confusing.
 

MaxHeadRoom

Joined Jul 18, 2013
28,510
If you have a board not shown that has the SCR's on it I would trouble shoot that for shorted device(s), using resistance check.
Max.
 

MisterBill2

Joined Jan 23, 2018
17,787
I had to scree shot them fuse f1 is the one blowing. I will give all info I can but honestly it won't stay on long enough to real trouble shoot
The very first thing to do is verify that the fuse is the size called for. If somebody stuck in one that is too low a current it will never work. That is a cheap and easy test to do first.
 

Thread Starter

Adam halcom

Joined May 7, 2017
22
Surely there is a better way than to de solder 100 different pieces when I have narrowed down that removing one wire from line 60 makes the issue go away
 

Owais451

Joined Jan 22, 2018
10
I purchased a welder over a year ago and haven't been able to use it due to it pops a fuse inside the welder. I have a ladder drawing but honestly I don't really understand all the ins and outs. It has one single layer PCB and honestly have no knowledge on how to check it. I can post the print for the welder. I would greatly appreciate any help because buying a new welder is not a option at this time. The machine is a old Linde ucc 305.
Dear Adam,
If you are not aware of components testing then first you should know how to check components which are in your TIG welder. If you are not interested to learn Components testing then get someone’s repair expert help near you. Then he will check components testing in your board and he will find shorted line or components in your board. I have great experience with components testing and troubleshooting for short circuits in boards but unfortunately I’m not there to help you.
 

Thread Starter

Adam halcom

Joined May 7, 2017
22
I appreciate everyone thought I got the board back in today and started rechecking the reference point I show140 v at line 59 should have 15 and 34 at line 71 and never changes when turning pot and 2 volts at line 80. Which makes me think bad step down transformer which overloads everything else. Let me know if I'm on the right path
 

shortbus

Joined Sep 30, 2009
10,044
The schematic is very hard to see, at least on my computer. If you could give a better version of it, it may get you more help. Even a link to the manufacturers site featuring the schematic would be good.
 

MisterBill2

Joined Jan 23, 2018
17,787
Dear Adam,
If you are not aware of components testing then first you should know how to check components which are in your TIG welder. If you are not interested to learn Components testing then get someone’s repair expert help near you. Then he will check components testing in your board and he will find shorted line or components in your board. I have great experience with components testing and troubleshooting for short circuits in boards but unfortunately I’m not there to help you.
The schematic is very hard to see, at least on my computer. If you could give a better version of it, it may get you more help.
I was able to enlarge the schematic on my screen and up until the bottom of what I can see, about line 60 or 61, I don't see the fuse. I would need to see the bottom half of the circuit board to evaluate the rest of the circuit. But now I have an interesting question, and the problem may be one that I have seen before, elsewhere. Is that transformer at the top set correctly. And what line voltage are you supplying? It appears that it can be set up for 120,220, 0r 240 volts, depending on where the jumpers are set. If it is set for 120 and you are feeding in 220 the fuse will certainly pop. So that would probably be a simple thing to check and an easy problem to fix. If you know the voltage that is supposed to be on the output of the first transformer you can disconnect one side and see if that is right. This is a cheap and easy firs thing to do, and if this is the problem then you are done checking.

Also, a screen shot, or better yet, a PDF, of the circuit below the transformer at line 59. If the fuse popping is below that point then I need to see the circuit to be able to offer advice. AND, as for trouble checking on that circuit board, most of the parts can be verified as to good or bad without unsoldering them. But you will need to have an ohm meter and some good probes. Capacitors like I saw typically fail in a short circuit, resistors fail open, and fuse-popping transistors and diodes fail with a short circuit. So an ohm meter with a low resistance range and a higher resistance range is what will be needed for that part of the check.


The schematic is very hard to see, at least on my computer. If you could give a better version of it, it may get you more help. Even a link to the manufacturers site featuring the schematic would be good.
 

Thread Starter

Adam halcom

Joined May 7, 2017
22
Well today I fell like a idiot after rechecking the step down I noticed I was hooked on the wrong tiepoint after rechecking the step down transformer is good. I tried to upload the entire file of the book that has all the schematic. But the file is too large I'll reattempt. I must say I truly appreciate everyone's help with this.
 

Thread Starter

Adam halcom

Joined May 7, 2017
22
Well today I fell like a idiot after rechecking the step down I noticed I was hooked on the wrong tiepoint after rechecking the step down transformer is good. I tried to upload the entire file of the book that has all the schematic. But the file is too large I'll reattempt. I must say I truly appreciate everyone's help with this.
 

MisterBill2

Joined Jan 23, 2018
17,787
All the jumper all connected for 230 volts.
If it had been wrong that would have been an easy fix! It was easy enough to check, and it would have caused the fuse popping.
I have not been able to see the bottom section of the schematic to see where the problem might be, or even to see where in the circuit that fuse is. I don't know if you can do a copy and paste from the online manual, all I need to see is the circuit. Diagnosing equipment has been a large portion of my career so I may be able to help without asking you to check all the parts. Probably it is only one bad part, but it may also be a wrong connection if something was not put back into the right place. I have seen that before. Also, I have seen problems from a screw fallen into an assembly. So there is another thing to check. That could be an easy fix still.
 
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