Did I fry my LED output?

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AlHounos
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Did I fry my LED output?

Post by AlHounos »

I'm using the neon output mods to send 5v to my ignitor through the LEDs. I changed resistors, and upon resoldering the wire to the resistor for spark output, I soldered one of them to the wrong side of the resistor. I only cranked it a few times, do you think this could have hurt it?

Also, one spark LED has 5v at all times
(on/not running, and cranking), and the other (the one i soldered wrong) has 0v at all times.
How can I test the circuit to see that it is still useable? Could it have damaged anything else?
md95
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Post by md95 »

If I understand how you wired it, you sent 5 volts directly to the LED transistor output. The LED transistors is what turns the LED's on and off, by switching ground to the LED's. This means you sent 5 volts directly to ground, when the transistor was switched on by the processor. I would take a close look at the LED that is resting at 0 volts, or the one you wired incorrectly. Take a close look at the board traces in that circuit as well. I'm thinking you only burnt the LED transistor...simple repair.
-Matt-
1998 Mitsubishi Eclipse RS 420A Turbo- MS2 Extra- 2.1.0 Release
1992 Plymouth Laser RS 4g63 AWD Turbo MS2 Extra- 3.0.3s
AlHounos
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Post by AlHounos »

I removed the transistors to get a full 5v to the spark outputs as per:
Project7 wrote:Ok, I have the car running 100%

I am firing the OEM miata ignitor directly from the top of R25 and R28 w/330ohm resistors.
You must remove the transistor for this to work. If you don't the output from the CPU will be to low to fire.

R25 with transistor (.72volts)
R25 without transistor (5.02 volts)

The Miata ignitor works as follows.
High (5v) Charging Dwell 9v out to coils
Low ( .23v) Spark

Running the Miata ignitor directly requires spark to be inverted.
Trigger Angle is 73deg for the 90-97 w/CAS
Dwell is 4.5ms for 90-93 with OEM Coils.

I noticed the charging output of 9v is kind of low. I'm going to see if providing a direct source of 12-14v helps improve spark energy. I would
imagine it would.
The traces all look ok, could it be something inside the processor?
MegaScott
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Post by MegaScott »

AlHounos wrote:I removed the transistors to get a full 5v to the spark outputs as per:
Project7 wrote:Ok, I have the car running 100%

I am firing the OEM miata ignitor directly from the top of R25 and R28 w/330ohm resistors.
You must remove the transistor for this to work. If you don't the output from the CPU will be to low to fire.

R25 with transistor (.72volts)
R25 without transistor (5.02 volts)

The Miata ignitor works as follows.
High (5v) Charging Dwell 9v out to coils
Low ( .23v) Spark

Running the Miata ignitor directly requires spark to be inverted.
Trigger Angle is 73deg for the 90-97 w/CAS
Dwell is 4.5ms for 90-93 with OEM Coils.

I noticed the charging output of 9v is kind of low. I'm going to see if providing a direct source of 12-14v helps improve spark energy. I would
imagine it would.
The traces all look ok, could it be something inside the processor?
If it were me I would have left the LED driver transistor installed, added a 5v or 12V pullup to the transistor output and see if that works to fire your module. The processor port can only source about 60ma, the transistor only uses ~5ma. But the output of the transistor can supply over ten times that amount of current to fire your ignition module.

If you tried to drive directly from the CPU pin to the ignition module with no current limiting resistor, you could easily fry the internal CPU port output driver.
AlHounos
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Post by AlHounos »

Yes, I wish I had done it that way now. Is the cpu output driver that might have fried isolated to that one LED? I mean, could I use D14 and D15 instead of D14 and D16, or do I need a new CPU?
MegaScott
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Post by MegaScott »

AlHounos wrote:Yes, I wish I had done it that way now. Is the cpu output driver that might have fried isolated to that one LED? I mean, could I use D14 and D15 instead of D14 and D16, or do I need a new CPU?
No, unfortunately you don't have those options, but you could use the fidle output.
AlHounos
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Post by AlHounos »

Ok, so the output driver goes to all three LEDs or all outputs? I assume this means I would need a new CPU, since I need more than one (fidle) spark output.

Just trying to figure out what I need to do to get spark on my car.
MegaScott
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Post by MegaScott »

oh, your using wheel decoder, sorry, I didn't catch that. There is a seperate driver for each output, I'm not sure you can sub the fidle output for output "A" on the decoder firmware. If you have a burned output pin, you are stuck with buying another CPU $18+shipping at the Vendors listed in the Products and services forum.
AlHounos
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Post by AlHounos »

Ok, I'm going to try using D15, but I'll probably have to get a new cpu. Thanks for your help.
jsmcortina
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Post by jsmcortina »

In Neon mode you can only use the outer two LEDs.

Do you have a stim?

If you do then hook it up and turn on "stim for wheel" setting which should then flash the LEDs. This should confirm if there really is a problem.

James
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AlHounos
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Post by AlHounos »

Ok, I thought maybe I could move the trigger on the wheel decoder to output C instead of B.
Like this:
Trigger Pos A: 1
Trigger Return Pos A: 0
Trigger Pos B: 0
Trigger Return Pos B: 0
Trigger Pos C: 2
Trigger Return Pos C: 0

I do not have a stim.

I poked around with the voltmeter on D14 and D16, and I'm getting 0.2v at the resistors when running on stock ecu, (spark on but not connected) and 5v on the bottom leg of the LED, and 3.3 on the top leg. So can I connect the outputs directly to the bottom leg of the LED instead of the resistor? I really appreciate the help Scott and James, because this is incredibly confusing for someone who is definately NOT familiar with electronics.
MegaScott
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Post by MegaScott »

You can try hooking to the bottom leg, but I was thinking you should use the top leg with an added resistor to 5V.
AlHounos
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Post by AlHounos »

Alright, I'll try that. Thanks.
jsmcortina
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Post by jsmcortina »

Without re-writing the firmware you cannot use output C instead of B. It just won't work right.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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AlHounos
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Post by AlHounos »

Spark! :D Had the spark outputs connected to the wrong side of the resistors. The BOTTOM of the resistors (heatsink is the top) on a V3 board is the correct side.

Has this changed from the V2.2 board? All writeups I have seen have been for a V2.2 and they say the top of the resistor.
MegaScott
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Post by MegaScott »

AlHounos wrote:Spark! :D Had the spark outputs connected to the wrong side of the resistors. The BOTTOM of the resistors (heatsink is the top) on a V3 board is the correct side.

Has this changed from the V2.2 board? All writeups I have seen have been for a V2.2 and they say the top of the resistor.
The V3.00 is a different board for sure, it pays to double check. You might as well order up a new CPU. :cry:
jsmcortina
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Post by jsmcortina »

I think you've got the wrong resistors altogether.

If you are talking the output from the LED side of the transistor, solder to the (-) lead of the LED and connect a 1k resistor to +5v.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
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