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Old 01-31-2012, 08:02 PM   #21
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Originally Posted by bcrx7 View Post
Not sure if anyone noticed, but MOV1 looks pretty burnt! Isn't that what dumps the voltage in case of a surge?
I guess I'm not seeing what you're seeing? It looks fine to me.

The MOV is installed between +12 (where it enters the MS) and ground. It is in some ways similar to a zener diode, in that it conducts when the voltage across it rises above a certain threshold- approximately 22 volts in the case of this specific part.

Its purpose in this application is to protect the MS as a whole from overvoltage conditions on the main +12 line coming into the unit, such as might be caused by a glitch in the alternator's voltage regulation.

It will not, however, be in any way affected by the +12 supply coming into contact with the CPU. The presence or absence of the MOV does not affect the operation of the MS under "normal" conditions (when the +12 supply is not in an overvoltage condition). It does not conduct any current during normal operation, and is not in-line with the power supply.
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Old 01-31-2012, 10:32 PM   #22
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based on what Joe P. said, no. the car was not running, and the battery was pulling 11.8v at the time.
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Old 02-01-2012, 12:20 AM   #23
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Alright. Its dead Jim.

Everything on the mainboard checked out fine, I did have two questions about this though, a few components showed lower voltage. my voltage at the battery during testing was 11.8v
u5 was 10.5v
s12c was 10.9v
and d9 was 10.9v

Does this say anything or is the cpu dead?

After this I tried to load firmware, no dice.

Any thoughts before I throw stock ecu back in?
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Old 02-01-2012, 12:42 AM   #24
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Originally Posted by Gryff View Post
Everything on the mainboard checked out fine, I did have two questions about this though, a few components showed lower voltage. my voltage at the battery during testing was 11.8v
u5 was 10.5v
s12c was 10.9v
and d9 was 10.9v

Does this say anything or is the cpu dead?
It's close enough.

Those three points should, in theory, all read the same, though slight variations are normal due to resistance in the probe. They key point is that they're within U5's operational threshold, and close enough to (battery - forward drop across D10) to be believable.

The most important test would be whether you have +5 at any of the various places where we expect it to live (such as the +5 hole near the proto area or pins 1, 20, and 31 of the CPU socket), but given your description of what happened, I'm leaning heavily in the direction of the CPU just being toast.
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Old 02-01-2012, 01:37 AM   #25
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yeah, they were all like 4.95. so plenty close enough. I was thinking it was toast, Just wanted to make sure that the 10v was not an issue.
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Old 02-01-2012, 03:21 AM   #26
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Originally Posted by Joe Perez View Post
If you touched 12v to pretty much any wires that directly interfaces with the CPU, the CPU is fried.

Unfortunately, microprocessors just aren't very tolerant of voltages higher than VDD on their I/O pins. This is why most (all?) of the external analog and switch-sensing circuits you see in the MS "hacks" section have series resistors and zener diodes in them- to protect the ECU from this specific condition.
This is a problem with the Freescale microcontrollers. Atmel AVRs for example have a 5.6V Zener diode on ALL their input/output pins. I've never managed to destroy one, I wish I could say that for the HC9S12
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Old 02-01-2012, 10:14 AM   #27
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Originally Posted by Gryff View Post
Lars was telling me that one could do that, or send it to http://www.pftuning.com/

But he said that cost you quite a bit of money back when ms3 was brand new.
If I get a new board im sure we could figure something out.

That's who i suggested to you.

IIRC I was charged around $90 shipped to have mine repaired--the second time.
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Old 02-01-2012, 02:07 PM   #28
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How quick was the turnaround?
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Old 02-01-2012, 02:52 PM   #29
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within a week IIRC. He's in VA Beach, so quick deliver times.
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Old 02-01-2012, 03:39 PM   #30
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cool, I emailed him this morning. Still waiting on a response, but we will see what happens between him and a friend of mine that may possibly have a card I can use.
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Old 02-03-2012, 01:44 PM   #31
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Slight update on this, Still havent heard from him. and My potential sources for daughtercards came up dry. So im going to go ahead and get the one I have fixed. The stock ecu is back in the car and almost running, just need to hook up the wb with nb signal, and set base timing.
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Old 02-03-2012, 10:25 PM   #32
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Another update, It lives! My only issue is that the tach does not work now, not entirely sure what the issue is. The car was running cops at one point in time, so therefore it has the resistor in the diagnostic box. I pulled that out to see if it made a difference, still no tach.
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