ESAB CaddyTig HF TIG inverter welder repair.

[pappkopp]

Hello, this wont be your normal test instrument repair but i hope it will be interesting
I’m trying to repair a inverter TIG welder i just bought, but i cant seem to understand it completely, the problem is that it wont power up, the main rectifiers are working, but there is no power to the logic section. I have have had a look at the service manual, and measured the points that are mentioned, i tried to replace a swiching mosfet. The D²Pak in the right corner (for the logic part i belive, internal diodes showed up as open circuit)

Please see the attatched service manal, as you can se on the Picture, there are two screw terminals, here is a +325VDC voltage measured and correct, and i belive it is somehow switched with the mosfet into the red/orange transfomer marked «UTK»
Could someone please help me troubleshoot this? There is no voltage at the output of the transformer, or the linear voltage regulators.

Kind regards And thanks in advance 
Service manual:
https://www.manualslib.com/manual/989932/Esab-Caddytig-Hf.html

[ivi_yak]

hi, could you check in out voltage on linear reg?

[pappkopp]

There is no voltage on the regulators.

[oldway]

The service manual does not contain the detailed diagrams nor the drawings of the PCB tracks as it is based on the modern principle of exchanging defective electronic cards with new cards.
It is not planned to repair the cards yourself.

So, it is necessary either to inquire with the ESAB representative on the possibility and the cost to exchange the card,or to do reverse engineering ....

If you do not help, without the diagrams, we also can not help you ....

Follow the tracks of the printed circuit and look for where the 5V power supply for logic circuits is coming from and why there is no voltage .... It seems to me that the 5V is produced from 19V or 24V ... .

Avoid changing components if you are not 100% sure that the part is defective.

Be very careful, in this device, there are high voltages that are not isolated from the network, it is very dangerous.

[KADOisblue]

Hi Guys, I know this thread has been dead for quite some time. However I'm going to try my luck...

I have the same ESAB CADDYTIG HF welder with a different fault to the one described , two surface components have failed on the same control board and I cannot read the part numbers on them.
I have attached pictures.
Does some one have access to the schematics?
Or have better photos of the circuits that would show me the part identification labels.

Thanks in advance.

Bret Martin