Repair Lincoln V205T AC\DC Main IGBT Inverter Board

[Mustafz]

Hi, after long time later, just start again try to repair my roasted main pcb ( called by Lincoln Main IGBT Inverter Board ) of Lincoln İnvertec V205T AC/DC welding machine. I want to try to share my knowledge and experience. First off all i need to circuit diagram roasted section of pcb which is called UPFR section. Many times searched to internet and can not find any information of correct version of this machine. And decide to draw scematic diagram of this section. I hope that if somebody need it and help out this circuit diagram. Also hoping that more people contribute and develop this thread it should be good guide to repair mentioned machine.

continue to share my experience below.

Regards,

 

[500e]

I wonder if the mods could move or copy all these diagrams to a link in welding machines so searching would be easier ? or a link to relevant thread all ways at top of makes heading
EG. Esab clivk circuits click
or a sticky the poster can insert the diagram \ description so all circuits or links all in one place,

 

[Mustafz]

UC3854 power Factor Preregulator chip is working as active power factor correction that working fixed frequency PWM on 40 Khz. You can see below PWM signal output images of UC3854 yellow trace and HEF4093 output is blue trace

 

[Mustafz]

just applied to +15 volt uc3854 circut section and test it by oscilloscope.

 

[Mustafz]

eventually, i have spent enought time to repair my broken V205-T AC/DC tig welding machine and fix it. Mosfets gate switching circuit HCPL0611 opto-coupler (isolator) IC was broken and it wasn't transmit to PWM signals to Mos-Fets that produce by UC3854. Replace it and now, the machine is working properly.

 

[eddie49]

Great work ! And thank you for the update.

 

[chris pruteanu]

Thank you! It will shure help someone in the future...

 

[Mikes]

eventually, i have spent enought time to repair my broken V205-T AC/DC tig welding machine and fix it. Mosfets gate switching circuit HCPL0611 opto-coupler (isolator) IC was broken and it wasn't transmit to PWM signals to Mos-Fets that produce by UC3854. Replace it and now, the machine is working properly.

Excellent work. Good to see the replacement of a component rather than the whole board. Did you get a cost for the whole assembly as opposed to the cost of the component that you replaced? Be interesting to know. Obviously you still need to have your electronic skills and the time to do it but very worthwhile in my opinion.

 

[Mustafz]

First of all, need to a small update for type of MosFets. Normally must be installed APT50M50JVFR but someone have used GB75DA120UP IGBT on my machine. I used to IXFN80N50 which is equavelent of APT50M50JVFR.

On this machine (Invertec V205T AC DC), PFC site mosfets are driving between -5V to +15V PWM signal producing by UC3854 which is fixed frequency PWM IC. My first check PFC driver mosfets was broken. This kind of fault, you can not test gate driver circuits as working normal operation of like on my machine. Because most probably faulty gate circuit is apply positive signal pulsed or DC continuously to mosfets gates and mosfets burn instantly on first second cause mosfets always trying to stay on state.

Stay only one way to test this kind of circuits. Externaly drive and test it by oscilloscope. I Applied to +15 and -15 volt by lab type power supply to proper connections on board and drive by signal genarator of after UC3854 output circuit between gates of mosfets and fixing easly broken IC HCPL0611 by this way.

After replace HCPL0611 with temporarly cheaper mosfets for trying to control all circuits as normal conditions as seen on photo. I have seen all signals and supply voltages are ok and the machine working good with all functions except trying welding.




Finally, replace mosfets with IXFN80N50 and test it for all functions 3 days throughout. Still working on it and now I am learning to make master of TİG welding . I still couldn't learn. So tig welding was very hard work and ist not similar to soldering

Hope that someone in need and use this post and I want to special thanks to @Bobbes for helping me.

 

[Seadog]

Well done. You clearly know your way around a circuit board

 

[Mustafz]

Did you get a cost for the whole assembly as opposed to the cost of the component that you replaced?

Yes, i asked authorized service and they gave me 1500 to 2000€ price for fixing this machine I asked because PFC site of main PCB was realy roasted both of two side

Obviously you still need to have your electronic skills and the time to do it but very worthwhile in my opinion.

So many thanks yours best wishes but I am not amateur only my english is not very good

 

[Bobbes]

Very good that you have solved your problems with this board. They are not simple. Good work and nice pictures.

 

[Json]

I have come across this forum and would kindly ask for help and clarification to determine what piece of the board failed by my photos. Lincoln Invertec V205T ac/dc. From previous photos on this forum I see the failed part but cannot zoom in enough to capture the data. I will show what I have available on my machine. TIA for any help to help find replacement part. Jason

 

[Bobbes]

It's a fuse of 1 Amp. 250 Volts from littlefuse

 

[Json]

Thank you Bobbes…what took place was finished welding and machine was running with fan on for a few minutes and loud pop with small amount of smoke. Not sure the cause or if small amounts of metallic dust collected causing any kind of issues. When looking at the little fuse website what is shown don’t resemble the failed piece still remains in my photos.

 

[SW1940SS]

It’s a 420 series your looking for

 

[Json]

. Located replacement fuse. Thanks.

 

[Graham_E]

Hi,

I own an Invertec 205T AC/DC also. I did not use it regularly, but went to use it a few weeks back and it initially worked and then stopped. I still get the HF start spark but no more..

I had some one look at it and he spoke to Lincoln who want £3,250 for a new circuit board and mosfets.

removing the board there is no obvious signs of burnt out components. I have ordered 6 new mosfet‘s just so that I know I have good ones. I would be interested to know:-

1) which component in the photos above is the opto isolator, ( I am not near the machine now to look closely at it)
Updated: I have found this - HCPL0611 Fairchild Optocoupler https://uk.rs-online.com/web/p/optocoupler-ics/8808675


2) the person who has a look at it, was satisfied that the input stage of the machine is ok and that the LED’s on the board show green. Does anyone know what the LED’s signify and how many there should be in total ?

When the new mosfet‘s arrive I will bolt it back together and I can then check for signals etc but would like to be prepared to know what to look for and so on.

thank you in advance for any help.

Graham

 

[eddie49]

Hello, and welcome to the Forum !

I had some one look at it and he spoke to Lincoln who want £3,250 for a new circuit board and mosfets.
I have ordered 6 new mosfet‘s just so that I know I have good ones.

Do you, your colleague, or Lincoln have evidence that the 6 MOSFETs are actually faulty?

Regarding replacing power transistors - this recent thread ( about an IGBT-based inverter-based welder ) may be helpful:

Parweld XTT182DV no power

I have an XTT182DV inverter set, which is currently not showing any signs of life. A preliminary investigation is showing that I am getting AC voltage to the first pair of rectifiers and when the DC side of the rectifiers is disconnected from the main PCB there is 240V DC. When the DC side of...

www.mig-welding.co.uk

 

[Graham_E]

Hello, and welcome to the Forum !

Do you, your colleague, or Lincoln have evidence that the 6 MOSFETs are actually faulty?

Regarding replacing power transistors - this recent thread ( about an IGBT-based inverter-based welder ) may be helpful:

Parweld XTT182DV no power

I have an XTT182DV inverter set, which is currently not showing any signs of life. A preliminary investigation is showing that I am getting AC voltage to the first pair of rectifiers and when the DC side of the rectifiers is disconnected from the main PCB there is 240V DC. When the DC side of...

www.mig-welding.co.uk

thank you for the reply

no, I do not know that the mosfet’s are faulty, I have tested with a multimeter and they are not ‘short circuit‘ which I understand in the common failure mode for mosfet‘s. As I get more familiar or more advice, I will check more out before they arrive.

My rationale for ordering them is that they will take a good few weeks to be delivered so I do not want to delay ordering if I confirm that they are at fault. But also, the machine is coming up to 20 years old, these components are doing the ’heavy switching work’ and from experience from working with clever people these have a ’life’, so replacing Is not a bad thing even if they are not at fault. (Noting, the spares catalogue for the PCB at £3,250 includes 6 new mosfets)