But obviously I am hoping the mosfets have failed open circuit…
- Thread starter Mustafz
- Start date
Thank you, will do…
My machine is old, the layout seems different.
Or am I looking at the wrong board. I have just sat down and now thinking this may be the wrong one.
Hopefuly this is the board you mean, but I can only see 1 diode.
Which when taken out of circuit is testing ok
Thank you
Or am I looking at the wrong board. I have just sat down and now thinking this may be the wrong one.
Hopefuly this is the board you mean, but I can only see 1 diode.
Which when taken out of circuit is testing ok
Thank you
I have finally had time to look at the welder in more detail.
I put an oscilloscope on the feeds to the Output IGBT module and found that I was getting the +51 volts and -51 volts to this. Video showing +51V and -51V
The trigger signals to the IGBT have a 10kOhm resistor on them to pull the signal low. On putting a multimeter across these I measured 10kOhm on one pair and a short circuit on the other.
I traced the short to a failed TVS (transient voltage suppressor) on the circuit that feed this trigger.
Having replaced the failed component the unit still failed to output. I then put the scope on the trigger signals at the output of the triggering circuit. I get the expected waveform to the -VE output trigger, but not on the +VE output trigger. Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the +Ve post.
this has been the long winded way of saying I believe the Output device has failed and I have ordered a replacement.
But no, it’s not that simple… The International Rectifier 92-0189 that is fitted is an obsolete component as IR were sold to Vishay in 2007. I cannot locate a copy of the IR 92-0189 datasheet to do a comparison for the replacement part. Therefore, I have ordered an Old Stock item from AliExpress which I now have to wait the few weeks for delivery.
let’s see how it goes when it arrives
this plot shows the trigger signal to the two gates on the output device. The two plots show the before and after swapping gate signals over. (apologies for the change in Y axis scales)
I put an oscilloscope on the feeds to the Output IGBT module and found that I was getting the +51 volts and -51 volts to this. Video showing +51V and -51V
The trigger signals to the IGBT have a 10kOhm resistor on them to pull the signal low. On putting a multimeter across these I measured 10kOhm on one pair and a short circuit on the other.
I traced the short to a failed TVS (transient voltage suppressor) on the circuit that feed this trigger.
Having replaced the failed component the unit still failed to output. I then put the scope on the trigger signals at the output of the triggering circuit. I get the expected waveform to the -VE output trigger, but not on the +VE output trigger. Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the +Ve post.
this has been the long winded way of saying I believe the Output device has failed and I have ordered a replacement.
But no, it’s not that simple… The International Rectifier 92-0189 that is fitted is an obsolete component as IR were sold to Vishay in 2007. I cannot locate a copy of the IR 92-0189 datasheet to do a comparison for the replacement part. Therefore, I have ordered an Old Stock item from AliExpress which I now have to wait the few weeks for delivery.
let’s see how it goes when it arrives
this plot shows the trigger signal to the two gates on the output device. The two plots show the before and after swapping gate signals over. (apologies for the change in Y axis scales)
Last edited:
Oh…. and I found values in the repair/service manual to be incorrect…. Which lead me up the garden path until a friend confirmed they were incorrect.
the output of the Unity Power Factor input board is 383Vdc. Hence the Voltage at the IGBT’s on the IGBT board will be 191Vdc. Not the 173V and 37V stated in the manual.
the output of the Unity Power Factor input board is 383Vdc. Hence the Voltage at the IGBT’s on the IGBT board will be 191Vdc. Not the 173V and 37V stated in the manual.
CORRECTION;
“ Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the +Ve“
Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the -Ve post.
“ Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the +Ve“
Moving the +Ve trigger wires to the -Ve solder posts I get and vice versa, I get the correct signals on the -Ve post.
Just found this link to a white paper on IGBT‘s in welders, published by International Rectifier who make the output device in my welder, it may be an interesting read to someone.
studylib.net
AC TIG Welding: Output Inverter Design Basics
Free essays, homework help, flashcards, research papers, book reports, term papers, history, science, politics
amazing how similar the Selco Genesis 200 welder is :-) worth looking at.
Also the manuals are word for word the same. https://www.manualslib.com/manual/952255/Selco-Genesis-200-Ac-Dc.html?page=5#manual
The Real Lewis
New Member
- Messages
- 4
- Location
- France
Hi,
Please allow me to reopen an old file.
I have physically blown the F1 fuse in my Selco Genesis 200 AC/DC (which has this same exact PSU card) and the C58 ceramic disc capacitor in the the switching power supply section has gone with it.
It is circled in red on the right in the attached pictures, it is the same size and color as some Vishay BC RR 471K 1KV on this same board.
Can someone be a gentleman and give me the reference for the C58 capacitor ?
If your experience gives you any sense of how this damage occured, i welcome your advice.
Sincerely,
Lewis
Please allow me to reopen an old file.
I have physically blown the F1 fuse in my Selco Genesis 200 AC/DC (which has this same exact PSU card) and the C58 ceramic disc capacitor in the the switching power supply section has gone with it.
It is circled in red on the right in the attached pictures, it is the same size and color as some Vishay BC RR 471K 1KV on this same board.
Can someone be a gentleman and give me the reference for the C58 capacitor ?
If your experience gives you any sense of how this damage occured, i welcome your advice.
Sincerely,
Lewis
The Real Lewis
New Member
- Messages
- 4
- Location
- France
Thank you for the reference.
Good intuition. Diode has no visible damage but is wide open.
I'll check the damage downstream to see where it finally blew over.
The Real Lewis
New Member
- Messages
- 4
- Location
- France
The diode was actually fractured in two, but still conducting. I had to take it out in two separate pieces.
No further damage has been found on passive components. I will order the components and post an update when they have been replaced.
Thank you again.
No further damage has been found on passive components. I will order the components and post an update when they have been replaced.
Thank you again.
The Real Lewis
New Member
- Messages
- 4
- Location
- France
I have received the components from Mouser and soldered them, cleaned the board and put fresh varnish on my solders.
Then i put everything back together nice an tight, plugged it and then bam! it started just fine like nothing ever happened.
Well played Bobbes, you got it all at first glance and i tip my hat to you.
I'll run some beads in the coming days to check that every function works and see if the fuse blows again.
Then i put everything back together nice an tight, plugged it and then bam! it started just fine like nothing ever happened.
Well played Bobbes, you got it all at first glance and i tip my hat to you.
I'll run some beads in the coming days to check that every function works and see if the fuse blows again.
Hello, I want to know if someone can help me with this.... I Have a welding store and this Invertec V205 AC/DC has been in exhibition for a long time, now I decided to turn on this machine to make some welding test for a customer, but hapened when I turned on the PC Board started to burn without any used. So I would like to know if some one has a pic of this part to make a rebuild of this one.
thanks for your support
thanks for your support
thanks for your support
thanks for your support
Selco Genesis 205 acdc, the very one I have. Frightens me inasmutch I know one day instead of welding I'll be fault finding a circuit board...
