How to check IGBT gate signal safely with oscilloscope ?

[BGAmodzX]

Hi everybody.

I am troublshooting an inverting welder that uses IGBTs as power components.

I usually remove IGBTs and check the signal across the gate and source pcb through holes.
But this devices uses 6 IGBTs and they are soldered in very precise way so that its hard to get them back exactly how they were positioned after desoldering them .

So my question is : can i check the gate signal directly on the soldered IGBT while the device is on ?

 

[Reloadron]

I don't see why not? Make sure the scope is properly grounded to the ground of whatever you are measuring. Depending on what you expect to see you may want to use a 10:1 probe to reduce any loading effect.

Ron

 

[BGAmodzX]

Thanks. I have grounded the scope and on the inverter board i have shorted the two thermictance connectors as acway to mimicknthe original set up.

But the probleme is i cant read the signals.

I will upload the pcb very soon.