Any one know anything about Fanuc vac drives? My question is about testing the transistor blocks in the base. When I test between the collector and emitter I get a spike of about 160ohms the it drops to infinity. When I go the collector and base I get infinity. That leads me to believe the transistor blocks are bad. I have checked the Input voltage, the encoder to the motor has been changed with a identical machine I have and meged the motor at 1000v to ground and it all checked out good. There are 4 of these blocks in the base of this drive and it gets pretty expensive replacing parts so I need to get things narrowed down before I just throw parts at it. I also would like to know what else is after these that could cause them to blow that I need to check. Any help would be greatly appreciated I just need to get the thing running again. This is a older A06b-6044-H011 drive and has a alarm 02 on it.

 

a VFD?

the "transistor blocks" are usually H-bridges and have a bit going on in them. best bet is to find a manual and look up the error. could be a bad bridge, could be flakey bypass or filter caps, could be anything! haha

I have a 2.5kw and 6kw drive sitting here someone game me to play with then went off a dissappeared.

---AutoMerged DoublePost---

is it a molding machine?

we have some fanuc machines where I work... i could ask about it for ya.

 

We have Fanuc PLC's at work. The newer ones are crappy....

So this thing is a PLC with a control unit connected to four "transistor blocks", each driving a separate motor? That's not the kind of thing we do with PLC's.

Use the "diode" mode of the meter to check transistors. You should have a couple volts to bias base to emitter and a couple volts to bias base to collector; the meter shouldn't be able to bias from emitter to base, collector to base, collector to emitter or emitter to collector.

 

No need to worry about it being a new one is 24 years old. Its on one of my Okuma cnc lathes. I think this one is 11kw but it could be 7.5kw. Cant remember of the top of my head I have a couple of each of them but it runs a 20 hp motor. There is a control unit connected to four transistor blocks but they all run one single motor.

I am going to have to get a better meter tomorrow to do that. Dang Darwin!!! I believe it suffered a power surge from a storm we had wiped them out. I am hoping and think that it just wiped the bridge out between them and nothing else. Is there anything I should look at after these to try and keep it from blowing these things right off the bat?

I am a machinist by trade so I understand about enough about this to confuse myself real good. Thanks for the help and any advice is appreciated.

 

Could you just junk the transistor blocks entirely and use the control unit to energize solid state relays?

Using a meter with a "diode-test" feature is definitely the right way to check transistors, at least your common three-pin transistors. Most every meter nowadays has a "diode-test" feature.

 

I have no idea if I could just junk the transistor block. I barley have any idea what I am doing. I am way in over my head.

The better meter I had grew legs and took off so the one I am using is just a cheap one. I need to buy a better one but I only work on these things rarely and out of necessity.

I have meged the motor to ground but not leg to leg with 1000v. I had heard to conflicting story's about using 1000v. One says its too much the other says its fine whats your take? And without blowing any fuses I have a hard time believing something else went and caused the transistors to fail but I also don't work on these things much. And what do you think the chances of all 4 transistor blocks going at once is? I can see it because when one goes it loads more to the others but I don't know?

Thanks for all the help. I know its not the easiest thing to tell someone how to fix one of these things that is at best mildly knowledgeable on them,

 

I'm not a CAM guy, but 1000 volts sounds like a lot for a motor. We have photo multiplier tubes that rock 1000 volts.

Where is this 1000 volts coming from? The power supply makes 1000 volts and the transistor blocks control it?

What does "meged out the motor" mean?

 

No the power supply doesn't make 1000 volts its 200v.

You have to bear with me I don't always know the proper names for everything.
When I say we meged out the motor I mean we sent 1000v through it to check for a leak in the insulation or short. I don't know if thats what is actually called just what I have hear everyone call it.

 

I wanna play with one...

 

do you mean checked it with the 1000v setting on the meter?

can you find a part number on the "transistor blocks" for us? that would be a huge help. they could be any number of different parts and they are all tested differently.

where the controller connects to these blocks, you should be able to measure a voltage(pulsed dc, should show up as ac) from there to ground while its in a running state, since the controller needs to give them an input to have them do their thing.

---AutoMerged DoublePost---

could you be speaking of a HI-POT test? apply 1000v to all the motor windings? no leaks and the box just beeps, otherwise it sparks and buzzes? haha

---AutoMerged DoublePost---

could you be speaking of a HI-POT test? apply 1000v to all the motor windings? no leaks and the box just beeps, otherwise it sparks and buzzes? haha