MS-Extra ECU Build Manual
ECU Build for MS1-Extra
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This is there for your protection.
All of these instructions / diagrams are to be used at your own risk, like most things there is more than one way to do the same thing, what we have tried to do is to offer a method that we have tested or that others have tested for us. No warranty expressed or implied.
Use at your own risk.
Please note: You can simply fit all of the components if you
wish. The explanation below is to save you fitting more than is needed, or
having to remove components you've already soldered in because they need swapping
for another value, need to be removed or simply aren't used.
It is assumed you can already solder, if not then there are lots of good articals that explain how to do that on the internet already, so we won't cover that here.
1) Decide if youre going to build your own ECU from a kit
of parts or buy a pre-assembled ECU.
2) If you decided to build your own MS-Extra ECU then get a kit off one of the recommended suppliers. The description below assumes all of the same valued components are in bags (e.g. R39 and R40 are the same value, so would be in one bag, C16 and C17 are the same values, so would be in another bag, etc) as they would be from a MegaSquirt kit supplier.
There are a few decisions to be made when ordering, these effect how its built:
|a) MS-Extra microprocessor:
b) Spark Output(s):
High powered spark driver (Directly firing the ignition coils)
Low powered spark drivers (External igniters, EDIS4,6,or 8 Module, etc)
c) Trigger Input:
VR sensor (used on most multi-teeth wheels)
Hall sensor, points, EDIS PIP, VAST, etc.
Coil -ve (Fuel only, rare now I think)
d) Idle Output:
PWM 2 or 3 wired device. You will need a TIP122 and a mica insulator for this.
No Idle Valve, some setups, like bike throttles, dont have idle valves.
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 dont 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)
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.
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). Note, D1 may need installing if your using a coil -ve triggering setup.
8) Now solder the 4 holes up on the main board for D1 and D2, so you dont accidentally add them.
9) Find D8 and remove it from the bag. (Keep this to one side as you may need it later, it's a 22V Zener)
10) Now solder up the holes for D8 on the main board.
11) Next you can fit all the rest of the diodes.
12) Next get all the bags of capacitors together, keeping them in the bags
If youre using the coil ve as the trigger input go to step 15 (This is rare now)
13) As long as youre 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 cant fit a capacitor into the holes by accident.
15) Find C22 and C14, C16 and C17. Solder these in. Note, these are polarised, ensure the lead with the + 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. Solder in MOV1 (looks like a big round capacitor.) (Not shown installed in this photo.)
17) Now find the bag with all the chips in it, U6, U3, U7 and U4. Solder these
in place, be careful to get them the correct way round! Also, be sure not to mix up U4 (IXDI404) and U7 (MC33072)
U7 could be one of two parts, the LM2904 works in 99% of cases though is being phased out and replaced with a substitute (MC33072) that has been shown to solve problems that a very small number of vehicles (e.g. LS1) may experience.
Note, the notch in the component must line up with the notch shown on the board. All notches face the top of the board, U6 notch to the left.
18) Find Q16, (Ignition Transistor), D14, D15 and D16 (LEDs) Q4 and Q20 (small transistors) and U1 (black 40 pinned chip for MS1) put these to one side, dont 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 R37s hole to hold the heatsink in place whilst you put the transistors in.
21) You can now fit all the other components, except for those that you put to one side! I fit the MAP sensor last, dont forget to bolt it in place with the plastic screws then solder it in once it's secure. Note, if using metal screws, dont tighten them up too much or the sensor case will distort and read incorrectly. This is installed with the writing facing you, the 'round' side goes towards the board. One of the pins has a small notch out of it which goes in the hole with 'notch' next to it.
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. Ensure the link is flat to the board as you may need a component on the heat sink later on in the build. Remember that without these current sense resistors, there is no over-current protection on the injector circuits.)
23) R43 is intended to allow coil current to be measured if you are using the Q16 high current coil driver. Unless you have access to an oscilloscope and plan on performing this test you won't need it. Either install R43 or link it out.
24) The board is now built to a basic level and is ready for a few tests:
a) Start by looking at ALL of the diodes and ensure
they are the right way round.
If you have any smoke then its likely youve put a diode in the wrong way round, this will mean finding it and fitting a new component. Once any component smokes it is no longer any use!
25)(MS1 jump to Step 26)
26) Idle valves:
ii) PWM Idle Valve:
2, 3 wired devices need a TIP122 and mica insulation.
iii) No Idle Valve:
26) Trigger input:
Remember you have already decided between VR, Hall or coil ve. Note,
Hall input covers all inputs like VAST, EDIS PIP, GM HEI, etc.
See the specific manual for youre engine's input to find out if its 5V or 12V. If in doubt measure the voltage with the engine stopped and ignition on.
VR Sensors Only (as fitted to most multi-toothed cranks, 36-1,
Hall sensors Only (EDIS, VAST, luminition, etc):
Coil ve Only (Firing trigger off ve side of coil,
Fuel Only) This is rare now!
27) Next we need to check that everything is OK before we plug in the microprocessor. Plug the board into your stim and power it up.
Ensure you have 0-5V on TSEL, if you get any more than 5V you have a wiring issue with the trigger input side. As long as you have 0-5V you can proceed to step 28.
28) Now your ready to test the board with the microprocessor in place. Fit U1 (black 40 pinned microprocessor) into the 40 pin connector.
Plug the ECU into your stim and turn the power on.
Feel the top row of power transistors, if they get hot at all turn the power off and check for faults.
If the microprocessor gets hot then turn it off. Slightly warm is OK, if any part is too hot to touch then there is a fault!
29) Next you need to figure out your ignition driver(s) See the MS1-Extra Ignition Manuals for information specifically for your setup.
30) Once the spark drivers are sorted, your ready to load the code into your MS-Extra ECU.
Pull up circuit diagram
List of component part numbers used in the ignition section:
DigiKey part numbers:
Farnell part numbers
1N4001 = 1N4001/4GICT-ND
1N4001 = 352-5326
Please note: Above part numbers will need checking, some components will come with a minimum order in multiples of 5 and 10.
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No part of this manual may be reproduced or changed without written permission from James Murray, Ken Culver and Philip Ringwood.