Explosion in my MS! Guess Fidle wasn't spark after all...

AndrewG · Post by **AndrewG** » Sat May 06, 2006 12:19 pm

Well a couple days ago I decided to upgrade to full ignition control and got my hall sensor and balancer cut with 3 slots. I hooked it up to the fidle which I thought was set up by the guy that built it but apparently he forgot.

Anyways, after cranking a few times I heard some fizzling and saw smoke out of the vacume line hole, oh crap....

Well apparently it was set up for a hall sensor input for the tach but not the spark output. What is the first thing that could be damaged if the IAC outputs were fed the negative lead on the coil?

To try and fix it after it blew up:
I went through the MSNSe info and removed r57, c12, and c30 as the instructions for installing the hall effect circuit without coil connection said. Then I installed the jumper from r26 to a 330ohm resistor and into IGTBin, then from IGBTout to IGNpin36. Now spark should go out pin36 and that goes to my coil negative.

But alas, it now doesn't power on. I'm not certain if it was still capable of powering on after it fried but I thought, during the chaos, that I looked at the screen and saw readings. So have I somehow hooked up the ignition output wrong or do I need to complete the fried IAC circuits even though I'm not using them?

My car is immobile now so thanks for any help guys!

AndrewG · Post by **AndrewG** » Sat May 06, 2006 4:48 pm

Does anyone have a picture of the v3 board underneath in that area?

I'm thinking if I see the traces that I could repair it somewhat. I thought I didn't even need the IAC stuff if I wasn't going to use it but I'm guessing it somehow interfered with the general operation of the MS.

newtyres1 · Post by **newtyres1** » Sat May 06, 2006 5:28 pm

Maybe start with the power supply checks in the manual (the ones that you would do if you were actually building up the board). You need to know if the main processor is still getting the 5V power and grounds on the right pins.

Ian.

AndrewG · Post by **AndrewG** » Sat May 06, 2006 8:31 pm

I am assuming I can do that with it just plugged into the car then correct? I haven't gotten a stimulator yet, it will be coming in my order if I end up ordering parts to fix this little snafu though.

I'll report back tomorrow if I have voltage or not. I don't get any leds lighting up or even any communication through the serial port so I'm guessing that there might be power problems. d8 is no longer installed since it blew apart so if that is more than just a component of the IAC circuit, that's probably my problem.

I might just be getting a partial kit for $90 if I can't figure it out, I'm sure with time I can fix this burnt up one.

Thanks for the tips.

AndrewG · Post by **AndrewG** » Sat May 06, 2006 9:33 pm

Heyo! I have power again!

Thanks to google image search I finally found an underside picture of a v3 board on the 18th page of results. It turns out the Q12 transistor has a trace that runs alll along the edge of the board and goes in by the IAC area. I guess that trace got blown out so I soldered a jumper from what was left of it and soldered it to where it originally met up.

I have to wait till the morning to load up Megatune to see if it fully works or not.

So, if anyone else for some reason doesn't doublecheck to make sure fidle is spark, odds are it will blow the IAC traces. If you don't have power after that, make sure that the one trace going from the transistor connects to where it should.

Hopefully all goes well tomorrow. Thanks for the help Ian, I'm going to be checking all my power areas just to be safe.

2001dodgeneonrt · Post by **2001dodgeneonrt** » Mon May 08, 2006 5:12 am

sorry im a little late, i have top and bottom side of MS 3.0 thx to DIY Autotune

http://new.turbort.com
I'll keep them up there in case someone reads this and needs them

Post by **jsmcortina** » Mon May 08, 2006 5:24 am

What exactly did you hook up to FIDLE ? (and why?)

Don't reconnect this to your car yet, I fear you will get more smoke and damage.

If you followed the picture you posted you'd be using LED14 for spark and nothing to do with FIDLE.

James

AndrewG · Post by **AndrewG** » Mon May 08, 2006 8:14 am

Yes I did reconnect it but only after I made the right connections. All those jumpers were added after it blew up

So basically if you hook up your coil to a stock fidle output, that is what you can expect.... I really should just stick to making my own stuff, tight deadline or not. I also think I was too excited and didn't triple check everything first.

Post by **jsmcortina** » Mon May 08, 2006 1:52 pm

AndrewG wrote:So basically if you hook up your coil to a stock fidle output, that is what you can expect.... I really should just stick to making my own stuff, tight deadline or not. I also think I was too excited and didn't triple check everything first.

Most certainly, connecting an ignition coil directly to a low-current output will burn something up for sure. You must either use the VB921 (Q16) or an external ignition module.

James

AndrewG · Post by **AndrewG** » Tue May 09, 2006 9:57 am

jsmcortina wrote:
AndrewG wrote:So basically if you hook up your coil to a stock fidle output, that is what you can expect.... I really should just stick to making my own stuff, tight deadline or not. I also think I was too excited and didn't triple check everything first.
Most certainly, connecting an ignition coil directly to a low-current output will burn something up for sure. You must either use the VB921 (Q16) or an external ignition module.

James

Yep, I just wish I would have made sure it was wired how I thought the original builder wired it. I should have built it myself anyways since it took him nearly two weeks to get it to me and by then I could have built one. Now it's pretty much dead :-/

When I blew a fuse the other day it must have sent enough of a jolt to make the D10 lead spark to the burnt out board around it and then D10 cracked. Since replacing it and isolating the wires so they can't short out, it hasn't started back up...

Post by **jsmcortina** » Tue May 09, 2006 10:07 am

You must have a short circuit on the board or some failed components.
That is what caused the fuse to blow and destroyed D10 in the process.

Remove the processor for safety and go through the power supply section of the board checking for failed components. What size fuse did you use? Try a smaller one next time.

The schematic is about 3/4 the way down this page:

http://www.megasquirt.info/ms2/pcb.htm

James

AndrewG · Post by **AndrewG** » Tue May 09, 2006 1:16 pm

Yes I found that the side of D10 closest to the db37 was shorting on the circuit board ground because the hole was burned out to at least twice the size it used to be. (I'm guessing there's a thin grounding layer running through the board or something)

I think I caught it too late though, if I would've stuck a small wire through there when I fixed it the first time it wouldn't have been able to short through the coating on the wire. I had it soldered to the traces when i fixed it that time also, this time I soldered straight to the components so I can be sure there are no shorts along the way.

What I need to find it out is exactly which way the power flows as it comes in to the MS. Then I can assemble those components seperately if need be, and stick them in the proto area.

Thanks for the links, I was just about to search out that info.

EDIT: I just remembered how I hate electric diagrams. I guess I need to read a book about it or something cause it always takes me like 2x longer to decipher that instead of a simple diagram. Like if that was all drawn over the top of the circuit board then I'd know exactly what's up with it.