MS1 to MS2 COP Resistor metod, no SparkB`

Ask questions about DIY board assembly issues, fault finding and testing. (Covers all Megasquirt versions and board.)

Moderators: jsmcortina, muythaibxr

Post Reply
cwdodson88
Helpful MS/Extra'er
Posts: 96
Joined: Tue Apr 15, 2014 7:39 am

MS1 to MS2 COP Resistor metod, no SparkB`

Post by cwdodson88 »

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.
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by Matt Cramer »

Please post what main board you have, and I'll go over how to troubleshoot the circuit.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
cwdodson88
Helpful MS/Extra'er
Posts: 96
Joined: Tue Apr 15, 2014 7:39 am

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by cwdodson88 »

Sorry Matt, it’s a 3.0 pcb. I have leds and a decent DVOM. Thanks for the help.
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by Matt Cramer »

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.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
cwdodson88
Helpful MS/Extra'er
Posts: 96
Joined: Tue Apr 15, 2014 7:39 am

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by cwdodson88 »

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?
cwdodson88
Helpful MS/Extra'er
Posts: 96
Joined: Tue Apr 15, 2014 7:39 am

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by cwdodson88 »

pin7 to 5v=d14
pin8 to 5v=d16 but its on constantly, bad transistor?
pin9 to 5v=d15
billr
Super MS/Extra'er
Posts: 6828
Joined: Sun May 15, 2011 11:41 am
Location: Walnut Creek, Calif. USA

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by billr »

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...
cwdodson88
Helpful MS/Extra'er
Posts: 96
Joined: Tue Apr 15, 2014 7:39 am

Re: MS1 to MS2 COP Resistor metod, no SparkB`

Post by cwdodson88 »

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!
Post Reply