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Megasquirt 2Extra (V3 board), 1997 Parallel Installation
Safety instruction from MS2 build manual (http://www.megamanual.com/ms2/V3assemble.htm):
Use an Ohmmeter (digital multi-meter set on resistance) to check the resistance between the three voltage
regulator holes. The voltage regulator is U5, near the DB9 connector in the top left side of the board (on the
heat sink). The resistance between any two of these three holes should be infinite. If it is not, contact the
supplier you bought the kit from. (This test ensures that the 12 Volt supply, 5 Volt internal supply, and ground
are not shorted together.)
MS2 Extra build instructions (http://www.msextra.com/doc/ms2extra/build_manual.htm)
3) Start the build by soldering in the 2 connectors (37pinned and 9 pinned items)
4) Next get all the bags of resistors together, keeping them in the bags. (R1, etc)
Find R12, R37, R38, R43, R39 and R57. Put them out of the way, you don't need any of them, but R43 may
come in handy later. Solder the holes on the board for R39 so you don't accidentally fit it. (The rest will be fine
as you shouldn't find these in the parts to fit if you've put them to one side)
R21, R22,R23.
Note from JBPerf.com: If using the external injectors, remove
BM Note: If it's a parallel install, don't install R4 and R7 or the Coolant and Intake temp signals will be
incorrect for the stock ECU. Removing these means these inputs won't work if you're running on a
Stimulator.
5) Now solder all of the rest of the resistors in place. Note: There is no polarity for resistors, so they can fit in
either way round.
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Summary of Contents for MegaSquirt 2Extra
- Page 1 Megasquirt 2Extra (V3 board), 1997 Parallel Installation Safety instruction from MS2 build manual (http://www.megamanual.com/ms2/V3assemble.htm): Use an Ohmmeter (digital multi-meter set on resistance) to check the resistance between the three voltage regulator holes. The voltage regulator is U5, near the DB9 connector in the top left side of the board (on the heat sink).
- Page 2 6) Next get all the bags of diodes together, keeping them in the bags. (D1, etc) Note, ALL of the diodes have a strip on them that MUST go the same side as the strip marked on the board! 7) Remove D1 and D2 from the bags and put them to one side. Keep both these diodes as you may need them (FIdle output mods).
- Page 3 12) Next get all the bags of capacitors together, keeping them in the bags (C1, etc). If you’re using the coil –ve as the trigger input go to step 15 (This is rare now) 13) As long as you’re NOT using the coil –ve as the trigger input (Fuel only) find C30 and put it out of the way. 14) Solder the 2 holes up on the main board for C30 so you can’t fit a capacitor into the holes by accident.
- Page 4 next to it on the component goes into the square pad on the board, this is also labelled with a ”+” on the board. 16) Now solder all the rest of the capacitors in. 16B) Solder in the two polyfuses F1 and F2. Solder in the two inductors L1 and L2, leave a little gap underneath.
- Page 5 40 pinned chip for MS1 or small daughter board for MS2) put these to one side, don’t lose them!! 19) Now place the metal strip (heatsink) in place and start fitting the main power transistors, remembering Q9 and Q12 have a piece of mica insulation under them to stop them touching the heatsink! Note, you can put a screw through R36 and R37’s hole to hold the heatsink in place whilst you put the transistors in.
- Page 6 20) Find Y1 (crystal) this is very very small. If your building an MS2 then you don't need this so put it out of the way. If you're building an MS1 then fit it so that the body of the crystal lays on the metal pad above the holes.
- Page 7 22) R37 and R38 are 'sense' resistors for the current limiting circuits on the injector drivers. Normally these should be installed. (If, however, you prefer to do without the current limiting and want to make two spaces on the heatsink bar, then you can instead link out R37 and R38 by soldering a copper wire between the 2 holes in each.
- Page 8 a) Start by looking at ALL of the diodes and ensure they are the right way round. b) Check that you fitted the mica insulators under Q9 and Q12 on the heatsink and that they look ok. c) Now you can plug it into your Stim and measure the voltage on the 40 pin connector U1: Put the -ve probe of your voltmeter on pin 32 of the 40pin connector (U1) Note, this is WITHOUT the MS1 or MS2 microprocessor in place!
- Page 9 25) MS2 ONLY (MS1 jump to Step 26) Solder a wire between s12c and JS9, this feeds the stepper motor driver on the MS2 daughter board. Even if you’re not going to use a stepper idle valve, it is needed to use the outputs for other items, like tacho, etc, so you might as well fit it now.
- Page 10 iii) No Idle Valve: (MS1 and MS2) a) Solder components Q4, Q20 and R39 in place. Note, this gives you a programmable output that can drive a relay e.g. cooling fan on FIdle (Pin 30 of the db37) Trigger input: Remember you have already decided between VR, Hall or coil –ve.
- Page 11 Following section is from http://www.msextra.com/doc/ms2extra/MS2-Extra_4g63.htm: Output Mods for V3.0 PCB Spark Invert mod from http://www.miataturbo.net/megasquirt-18/better-spark-out-circuit-33964/ The solution is to configure the spark outputs such that they are on when the CPU’s output pins are on, and off when the CPU’s output pins are off. We could achieve this by using a PNP transistor on the CPU output pin (PNPs have the opposite control polarity of NPNs) (edit: no, that wouldn't work) however since NPNs are already a part of the the modkit packages of the various distributors, I’ve chosen a route which...
- Page 12 Invert spark A and spark B on MS board so Spark A goes to pin 31 and Spark B goes to pin 36. (http://www.miataturbo.net/megasquirt-18/ms2-standalone-stock-ignitor-70414/). As you can see, we’re using the natural pullup of the existing LED to drive the base of the new transistor,...
- Page 13 which is connected to the collector of Q6/Q8 where the old spark output used to be. In this configuration, the output at the collector of the new transistors is exactly the opposite of what’s happening at the collectors of Q6/Q8, which is turn have always been the opposite of what’s happening at the CPU pins driving them.
- Page 14 Installation of 4-channel injector board (http://jbperf.com/sequential/index.html#ms2mods): The picture below shows the modification which connects pin 1 of the NAND gate chip (U2) on the MS2 card to pin 4 of the 40-pin header and pin 4 of U2 to pin 5 of the header. With that modification, pins 3 and 7 of the MS2 CPU can be used for injector channels 3 and 4, respectively, as shown below.
- Page 15 These new signals are taken at the input of the NAND gat chip since it a much more convenient location (closer to the header pins and more space to solder jumpers). The black lines in the schematic below show the new jumpers connection.
- Page 16 The picture below shows the placement on the V3.0 board of the 4 injector channels. The standard injector drivers components can be left on the board but will be unused and will not interfere with injector channels 1 and 2. The injectors channels 3 and 4 connect to pads originally used for the MS1 clock circuit and require the removal of those components for proper and safe operation.
- Page 17 Signal GND should connect to Megasquirt sensor ground. If present, Power GND should connect to the engine block along with the other Megasquirt power grounds. You may choose from either pin 'JS5 (ADC6)' or 'JS4 (ADC7)' either requires a hardware modifications inside...
- Page 18 Assemble the circuit on the prototype area of the mainboard and connect your MAF signal into the case through a spare pin on the DB37 connector. e.g. One of SPR1,2,3,4 if they are free. BM Note: I chose SPR2, normally allocated to CAN.
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