MS1 to MS2 COP Resistor metod, no SparkB`

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MS1 to MS2 COP Resistor metod, no SparkB`

Postby cwdodson88 » Wed Jan 03, 2018 2:21 pm

Doing an upgrade for a friend, switched from MS1 single coil to MS2 with COP. I removed the onboard BIP as he wants a separate DB15 for coils, so I built the spark outputs using the resistor method for ease and space constraints. Going through the testmodes to check the spark outputs with software commanding "going low", and spark b just lights an led solid, all others will be lit with little "off" blips corresponding to dwell time. Switching the outputs in the software from going low to going high and leds are off and flash corresponding to dwell, but nothing from spark b. I've checked the jumpers, and connections, and I cannot find anything. At this point its going to be something that I'm overlooking, but I cant wrap my head around what else, or what to test.
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby Matt Cramer » Thu Jan 04, 2018 6:08 am

Please post what main board you have, and I'll go over how to troubleshoot the circuit.
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby cwdodson88 » Thu Jan 04, 2018 7:37 am

Sorry Matt, it’s a 3.0 pcb. I have leds and a decent DVOM. Thanks for the help.
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby Matt Cramer » Thu Jan 04, 2018 12:33 pm

First step - remove the processor, and run 5 volts to processor pin 9 with the board powered up. Does the D15 LED light up? You can test the other LED outputs with pins 7 and 8 for comparison.
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby cwdodson88 » Thu Jan 04, 2018 1:08 pm

Thanks Matt,

I'll give this a try tonight.

If I am unable to light the LED, is there something specific to look at?

If the LED is fine, what should I look at?
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby cwdodson88 » Thu Jan 04, 2018 9:48 pm

pin7 to 5v=d14
pin8 to 5v=d16 but its on constantly, bad transistor?
pin9 to 5v=d15
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby billr » Thu Jan 04, 2018 11:07 pm

Yes, a bad Q8 or a solder bridge at one of those itty-bitty pads. Check that the transistor is installed the same direction as the others, but I think the base lead on those is the center one, so I don't think the LED would be "stuck on" even if the transistor was backwards. Also check that the CPU socket is at near-zero volts when the socket is not jumpered to 5V. I'm not certain exactly what it should be, floating like that, but it should be similar to what you see at the sockets for the other two LEDs.

PS: No matter how young and perfect your eyes are, bright light (like direct sun light) and a magnifier always help for visual inspection of PC boards...
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Re: MS1 to MS2 COP Resistor metod, no SparkB`

Postby cwdodson88 » Fri Jan 05, 2018 9:13 am

Well that’s exactly what it was. Thanks. I’m not sure how I missed that in my poking around but I replaced the transistor and made sure that everything was clean and each leg was isolated. Now it all works.

Thanks again guys!
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