Heckfire, Huck! 30v's confounded my MS
 

So after having no voltage regulator via 01+ alternator I managed to send 30 volts thru my car. Causing this:

Attachment 198125
Attachment 198126
Attachment 198127
Attachment 198128

Left a nice black spot to show me how bad I am. Burned and crack two transistors :(

Is this fixable? It seems to be but just want an experience eye to tell me yay or nay.

Totally fixable. How easy it will be will depend on whether or not you killed any surface mount capacitors in the process.

Also -> Who has to thumbs and called that shit like a pro?
<--This guy ;).

You don't need the one labeled MICA underneath it. But it's a tip125.

the 5V voltage regulator can be picked up at radio shack and replaced...hopefully that's the only thing that fried.

Yeah, you made my day sad :(.

Im taking it to a computer guru friend of mine. He's worked on shit like this for a good while, he will hopefully be able to fix it for me.

Hopefully the track didnt lift

so the 5v is the one that you can barely see?

what is the tip125 used for?

Sorry for that :(. Look on the bright side though, at least you were saved from dumping a bunch of money chasing gremlins while all the while the megasquirt had fried bits.

Also a good consideration, but the MS boards are built pretty sturdy.

The 5v reg (U5) is the left-most TO220 part.

The two TIP125s are part of the PWM damping circuit, which are used only when you are running low-impedance injectors.

Oh I see that I fried 3 transistors. That 5v, the most left-most one that Joe said and the two tip125s near where it says MICA. Im going to replace all of them for sure though.

The track doesnt look to be lifted or swollen in any way as well.


Another thing, when I plugged a plug to check spark, when I turn the key over it sparked, but wouldn't spark when I was cranking. Is that because the 5v is fried?

it'll spark with power on. but it's now not seeing your CAS input. If the insulators underneath the TIP125s failed and the body is making contact to the heatsink it will fail to operate...plus it's not getting VCC power to most things from the 5v reg that blew.

Cool, makes sense. Now I just need to get it fixed.

hope you didn't fry the processor!

The CPU, ironically, is not the most expensive component in that device. DIY sells 'em for $18.

What are the chances the processor and other important components went out as well? I've seen some pretty worn down processors from overclocking but this is a totally different ballgame lol.

I've had two boxes in my hand that had caught on fire...only a few select spark circuit components were bad. everything else was fine! Looked a LOT worse than yours.

wow, looks like you are going to be banned soon...

It's possible you may have fried D12 or MOV1 as well. But I have fixed ECUs with worse damage than what I can see in that picture.

:noob: here

Are those transistors as well? If so which ones are they and can I buy them from somewhere?

D12 is a diode. MOV1 is that big flat disc thing.

Sorry about the bad news. I do have one question though. Why were you running the 01 alternator? Is there a perceived benefit to running it or was it just what you had laying around?

I just had it laying around. Lower mileage than my 97 alternator. Plug is the same, ground is the same, had no idea 01+ use an external voltage regulator tho lol.

btw, thx brain

You can tell what kind of part something is by the reference designator.

Anything beginning in Q is a transistor (which includes FETs). If it starts with U, it's an integrated circuit (note that U5, the 5v regulator, is technically an IC, even though externally it only has three pins and it looks like a big transistor.) Parts starting with D are diodes (including LEDs), R for resistors, C for capacitors, Y for crystals, K for relays, etc.

You know, this is an excellent question. I can't for the life of me seem to find a BOM for the 3.57 PCA.

Some sleuthing is in order...

D12 is a Zener diode, which in the 3.0 BOM is a 1N4749. 22v, 1 watt, and from the pictures it looks to me like it's in a DO-214 package on the 3.57 board. I'm going to call it an SMA4748. Twenty-one cents from Mouser: http://mouser.com/ProductDetail/Taiw...GrvkMHLekDw%3d


MOV1... Well, it's obviously a Metal Oxide Varistor, a kind of Transient Voltage Suppressor. Varistors are interesting little devices which are typically used as surge protectors. Those power strips you buy for lightning protection contain them.

This one's proving difficult. This one is close, but I think it's a little larger than the one on the 3.57, and it has a lower surge energy rating than the one on the 3.0 board: http://mouser.com/ProductDetail/Litt...c3Hpfx7tgkI%3d

It'll definitely work if you can't find something closer.

This one's another possibility, again, it's close but not exact. Has a very low surge energy rating, and is physically a tad smaller than the stock one: http://search.digikey.com/scripts/Dk...=495-2593-1-ND

Fortunately, the MOV is not at all a mission critical part. It's job is to try and protect the rest of the board from transient overvoltage conditions, which is exactly what you did to yours. (And obviously, the MOV failed to do its job there, because you exposed the board to a sustained overvoltage, not just a quick surge.)

Oh man all it takes is a post from Joe Perez that is longer than 3 sentences to remind myself on how much I dont know lol.


Thx for the help! Looks like all these parts are sub $2, I can dig it.


Thankfully I got a guy I autox with that solders under a microscope daily and will be able to fix me up :). Will probly use this thread as a reference for parts too.

I need help figuring out what the part numbers are for the 3 transistors.

My friend says once he gets the MS he could probly get enough info off it to figure it out, but if one of you guys knows it off the top of your head that would be great :)

He's also going to look at the d12 diode and the MOV1 suppressor.

He uses digikey.com for the parts he gets at work.

Any help is much appreciated!

Understand, I guess that is one of the pitfalls of the little miata; parts that fit the same but work differently. hopefully the MS isn't hurt to bad.

Tip125tu-nd
p7315-nd
lm2937et-5.0-nd

Thanks again, your still my hero :)

Ah yes, thinking MS2 here. I once made the mistake of using a LM2940-12 instead of a LM2940-5. The 5.6V zener held out for a couple of minutes, but than I started getting connection drops. A couple of minutes later, the zener gave up and the 5V rail got 12V. It took out the MAX232, JB's PWM converter cpu and the MS2 daughterboard. The rest was 12V proof :)

Joe,
You did it the hard way. ;)

http://www.diyautotune.com/catalog/m...arts-c-50.html

Well so far my friend found 2 traces blown, and 2 resistors blown.

It would help him tremendously if he has a schematic to look at :).

That 30 volts fried more than I thought. The traces that blew weren't visable in any of the pictures.

Well my local autox region is saving my ass here. But heres whats blown so far:


List of bad so far:

1) U5, LM2937ET-5.0 removed under suggestion it is bad, have not verified operation, but they are cheap to replace
2) Q12, TIP125TU, blown up, removed what was left.
3) Q2? TIP125TU, blown up, removed what was left.
4) R30, possible 271 ohm, center digit scorched, removed, open- resistor cracked in 2
5) R34, value??, top burnt off, removed, measures 425 ohm
6) Trace melted apart between C14 & D21, installed jumper
7) Trace melted apart between D10 & D12 on D12 side after the via. Installed jumper
Trace under P2 (37pin DB connector) shows evidence of overheating, coating burnt off but not severed at pin28 on the smaller width trace.


My friend was wanting to know if theres any other places you guys have seen to be bad on another over voltaged board before. Theres also a short is between 12V and GND. Between 5V and GND is about 600 ohm. And the large electrolytic marked 3300uF 25V measures 3.08mF when desoldered from the board.

Just trying to get this straightened out. Need to build a MS myself so I can have a better grasp on all this lol.

Any help is much appreciated.

My MS died once when it was being powered by the stim, which was powered by its AC adapter when my apartment experienced an electrical issue. My failure was a quick zapping though, not due to a prolonged over-voltage situation, and I had nothing visibly burned or melted. Here's my thread from almost two years ago.

Cliff's: I'm not enough of an electronics whiz to pinpoint a single failed component so I wound up looking at the power supply schematic on the megamanual site (they have the v3.57 schematics too) and replacing all that stuff- diodes, caps, U5, MOV1, F1. So I used a shotgun instead of a scalpel, but I got 'er done.

Reading that now :)


Oh yeah, I kind of forgot about cursing in thread titles. I was in a state of rage when I made it, sorry!

Well this snowballed into a lot more problems than I first thought. There seems to be quite a bit of internal damage to the board, so Im guna opt to buy another board or maybe catch the next batch of MS3 :)

thats cool you wanna give it to me for free now!

Haha, I was going to sell it for dirt cheap if you want fix it.

My friend found his MS stim to test it out, there were quite a few problems. Injectors always on, leds would flicker then go off, idle air control wouldnt stay on, fuel pump would stay on for 1-2 minutes then go off, few others. I can ask him for the full list if you want me too brain.

Im sure you could have this fixed in a hurry :P. Just time consuming for my friend.

Actually.... you got PM.

That's a load of BS. It's worth at least $5, and I'm fully prepared to offer him double market value.

Lol, Joe Ill forward the PM I sent to Brain...... which I spelled fried wrong..... fml

I say to hell with fuxed boards!

+1

I got figure out how to get my car running on the stock computer again. I don't think the stock 97 map will take advantage of the 99 head or 01 block thats in my car :(

It'll work.