Hello all! I have a CNC machine that uses igbt transistors EVM31-050A on the spindle drive. Sometimes they go bad. I just test them with a multimeter, but there should be a way to set up a test board with lets say 120 v and a light bulb to test under load. Does someone know how to set up such a test board?

 

Power semiconductors when they fail, always fail short circuit. A DMM should be sufficient to test them.
However if you would like to test them in operation, a 12V supply for the collector and an automotive light bulb, with the gate driven by a 9V battery should be enough

 

Power transistors often fail as a shorted circuit, unless they fail as an open circuit, which also happens. And on some occasions they fail as leaky, although that was most often germanium audio power transistors, which are seldom found, except in old equipment, sometimes. Usually a reasonable test in an active amplifier circuit is to measure the base to emitter voltage, and then measure the voltage across the emitter resistor. If the base to emitter voltage is around 0.7 volts then the transistor is probably not shorted, and if the voltage across the emitter resistor is not zero then the transistor is probably not open.

 

One of the most common tests for an IGBT test is the dynamic test of charging a 40 to 100 W bulb in its collector and powering the circuit with a voltage of up to 100 VDC. With the gate connected to the emitter of the transistor, it must remain in the cut and with this the lamp is off.

 

This is a PANASONIC/Matsushita part. Here's the datasheet- look at the power curves etc, it will help you better understand the FET:

 

One of the most common tests for an IGBT test is the dynamic test of charging a 40 to 100 W bulb in its collector and powering the circuit with a voltage of up to 100 VDC. With the gate connected to the emitter of the transistor, it must remain in the cut and with this the lamp is off.

Do you have a scematics or sketch of the circuit?

 

Is it really necessary to have a schematic presented for every suggested set of connections???
(Balance of comment deleted)

 

Hello all! I have a CNC machine that uses igbt transistors

Out of interest, what make of CNC M/C is it?
Is the spindle performing a particularly high current operation when it occurs?

 

Is it really necessary to have a schematic presented for every suggested set of connections???
(Balance of comment deleted)

You know, I am not an electrician nor do I have any basics in electronics. I do repair my CNC machines with the very basic knowledge that I have. That is why I kindly asked for schematic. I assumed we are here on the forum to help each other. If it is too hard for you to lend a helping hand, fine, probably someone else could help me out

 

probably someone else could help me out

I was involved for some years in the design and shop floor maintenance of many kinds of CNC M/C's and may be able to help if the M/C is familiar!

 

Out of interest, what make of CNC M/C is it?
Is the spindle performing a particularly high current operation when it occurs?

It is a Okuma from the mid 80s. Yes the spindle is performing a high current operation

I was involved for some years in the design and shop floor maintenance of many kinds of CNC M/C's and may be able to help if the M/C is familiar!

It is a Okuma LR15-MY machine from the mid 80`s

 

SAVE THE DAY!!! Max!! Fix the problem!!