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Deodanth

Mon Mar 11 2013, 08:36PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Hi guys, this is a terrible way to introduce myself but I've been lurking as a member trying to learn stuff for a while.
I find myself in jam and despirately need help
This is my 13-y/o Liam as Tesla

Liam is a Tesla fan so when his science teacher assigned him to do a science fair project on his favorite scientist the choice was obvious.
the aspects of this project include:

a project and experiment
a costume
a report on the scientist

the pic is the costume, the report is done and for the project I sprung for EVR's Micro Brute DRSSTC kit.
We built it over christmas break and have been going back and forth over emails with McCauley for two months. We had it working too after sending it back to EVR and paying for a little bench time to find that I'd made a simple mistake. Dan M has been really nice and even tossed in some bench time. I definately don't want this to sound like a complaint about EVR or Dan.

We'd just recieved the board back in the mail from bench testing at EVR and hooked everything up and had it running by the book. It was great to see the grin on Liam's face.

Then we had a coil strike.
There had been a break in the secondary that happend while Liam was winding his first coil. I stripped out the wire and soldered it back together but I guess I didn't trim the ends well because there was a small piece of wire that acted as a breakout point to the side of the coil.
This is where a spark released back to the coil and the fuse on the coil power side blew.
I've replaced the fuse but no longer have resonance buzz. I don't have time to send it back to EVR. Hes supposed to demo his project at the end of the week.

If anyone lives in MD and can help, I'm willing to drive to your location, buy beer, buy parts, whatever.
I would really be greatful for the assistance.

Deodanth

Mon Mar 11 2013, 08:53PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

I just wanted to add that I have nothing but good things to say about Dan McCauley. He's tried to help within his ability and has been very gracious about my stream of questioning emails.

Ben Solon

Mon Mar 11 2013, 09:32PM

Registered Member #3900 Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600

It's almost certain that it's a set of blown igbt's. I'd help if I could, but as you might notice, i'm a couple states too far away.

The only thing I can offer is my opinions on how to go about fixing it asap:

if you don't already have one, buy a multimeter to test mains power on the bridge. if there's power being applied to the igbt's you can check that off.

you also might want to check the controller at the gate driver output to the gdt. an led and series resistor will indicate whether or not gate drive is working. to do so, you must feed a signal into both the current feedback enters the controller as well as driving the interrupter. if gate drive checks out, then the problem is pointing towards the igbt's.

set the multimeter to continuity and check between all the pins. continuity should only be achieved from emitter to collector. don't worry if that isn't displaying, as the freewheeling diode's voltage drop may throw you off.

if you can't check and test every component for function, i'd recommend just replacing the igbt's. if that doesn't fix it outright, then do likewise for all of the ic's on the controller. high voltage has a nasty habit of sneaking around to the weirdest places in a circuit.

sorry if my reply is a bit jumbled. hope this helps.

Deodanth

Mon Mar 11 2013, 10:00PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

I do have a multimeter.
Help a novice out a bit as I dont recognize all of the lingo.
GDT= ? gate transformer?

Physics Junkie

Mon Mar 11 2013, 11:03PM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

GDT=gate drive transformer. It does sound like blown IGBT'S. Ben is right but I'm not sure why he said "continuity should only be achieved from emitter to collector" you should NOT be having continuity between collector and emitter. With the IGBT'S still installed, you will know right away if they are blown if you check continuity between gate and collector and you get the buzzer. Same with emitter to collector. I would also recommend placeing a quick order of IGBTs from mouser.com or something with fast shipping. If you can, remove all of the IGBT'S, check continuity between gate-emitter and collector-emitter and gate-collector on all of them. There should not be any continuity between all these pins, except for the two emitters, if this is confusing, i have a few blown IGBT's i can demonstrate this test for you if it helps. Inspect the secondary again to make sure that the damaged area is not broken again

Ben Solon

Tue Mar 12 2013, 12:16AM

Registered Member #3900 Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600

Physics Junkie wrote ...

Ben is right but I'm not sure why he said "continuity should only be achieved from emitter to collector" you should NOT be having continuity between collector and emitter. With the IGBT'S still installed, you will know right away if they are blown if you check continuity between gate and collector and you get the buzzer. Same with emitter to collector.

You describe it better than I did, I don't like going into extreme detail if i know i'll be typing for a while

. What I mean by emitter to collector(as opposed to collector to emitter) is that the freewheeling diode built into the igbt(if it has one) will act as a short circuit minus the voltage drop when measured in that reverse direction. Everything else should be an open circuit.

You could probably eek by with to-247 igbt's if you can heatsink them properly and botch them in there without any significant inductance added. It would be cheaper, and more available than the so22whatevers that we all used to use. As I understand it, you don't need the extra couple inches of sparks as this is more of a school project, and not one of our ocd every-millimeter-counts coils.

Physics Junkie

Tue Mar 12 2013, 01:00AM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

ben123324 wrote ...

What I mean by emitter to collector(as opposed to collector to emitter) is that the freewheeling diode built into the igbt(if it has one) will act as a short circuit minus the voltage drop when measured in that reverse direction. Everything else should be an open circuit.

Ah yes, duh, I'm sorry I just misunderstood you

The IXGN60N60C2D1 (which should be the IGBT that the microbrute uses, I believe) does indeed have a diode built in. If the IGBT is blown though, then continuity will be between all pins, that;s been my experience at least

Deodanth

Tue Mar 12 2013, 08:02AM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Physics Junkie wrote ...

I would also recommend placeing a quick order of IGBTs from mouser.com or something with fast shipping.

good advice - DONE

Physics Junkie wrote ...
If you can, remove all of the IGBT'S, check continuity between gate-emitter and collector-emitter and gate-collector on all of them. There should not be any continuity between all these pins, except for the two emitters,

Hmm I tested them on the heatsink and there was contiunity...I had it backward in my head.

Physics Junkie

Tue Mar 12 2013, 11:16AM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Deodanth wrote ...

Hmm I tested them on the heatsink and there was contiunity...I had it backward in my head.

Okay, just be careful that you test the right pins when leaving them on the board because G-E will also look like a dead short with the GDT attached.

Deodanth

Tue Mar 12 2013, 02:23PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Physics Junkie wrote ...

Deodanth wrote ...

Hmm I tested them on the heatsink and there was contiunity...I had it backward in my head.

Okay, just be careful that you test the right pins when leaving them on the board because G-E will also look like a dead short with the GDT attached.

Just to be clear, I said on the HEATSINK because in EVR's kit they are attached to a big aluminum heatsink and then screwed to the board. I removed them from the board, but didnt want to unscrew them from the heatsink and peel it off of the heatsink paste.

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