V3.0/MS-II
I have Q16 installed but the SAW line stays high. Should this be wired differently for EDIS? Thx.
Should high current driver be used with EDIS?
Moderators: jsmcortina, muythaibxr
-
Jim Blackwood
- Experienced MS/Extra'er
- Posts: 252
- Joined: Thu Jul 29, 2004 6:31 pm
- Location: Gunpowder Rd
-
Jim Blackwood
- Experienced MS/Extra'er
- Posts: 252
- Joined: Thu Jul 29, 2004 6:31 pm
- Location: Gunpowder Rd
-
Jim Blackwood
- Experienced MS/Extra'er
- Posts: 252
- Joined: Thu Jul 29, 2004 6:31 pm
- Location: Gunpowder Rd
OK, I've done a bit of backtracking and find I do have the 1K pull-up resistor connected to the 5v source above the proto area and the circuit matches the one shown at http://www.megamanual.com/ms2/Ignition.htm
IIRC I asked about this circuit at the time I built the board because it seemed to make sense to go ahead and use the transistor Q16 to isolate the external wiring from the processor since it was on hand and it looked like the only change necessary to do this was to add the pull-up resistor. This also looked like it would allow the controller to run a coil directly with no changes except the ignition settings. Why it isn't working that way I don't yet know, but it looks like my next task is to test the input to Q16 with an LED and see if I am getting a signal there which changes with conditions.
Plugging an LED into the space for R57, I find that varying the rpm does cause a change in the intensity of the LED and switching off the stim tach signal causes it to go out. The interesting thing is that the (extra) ign LED on my stim operates in reverse fashion, indicating that Q16 is probably inverting the signal and this makes sense considering that Q16 is sinking to ground but it is too bad it didn't work out the other way as it would have been handy to have an increased level of interchangeability between units and vehicles. Oh well. I suppose there is a way to do that but probably not with this transistor, unless it could be done by simply removing R43 and allowing Q16 to function as a diode. Probably nothing to be gained by doing that but the transistor is installed...
Nope, all that does is leave the Ign LED on all the time so apparently the junction is going the wrong way for it to work. However I can now bridge the leads of Q16 and get the desired results, meaning that if at some future time I want to use this controller to directly drive a coil I can simply unbridge Q16 and resolder the lead of R43 and it's good to go.
IIRC I asked about this circuit at the time I built the board because it seemed to make sense to go ahead and use the transistor Q16 to isolate the external wiring from the processor since it was on hand and it looked like the only change necessary to do this was to add the pull-up resistor. This also looked like it would allow the controller to run a coil directly with no changes except the ignition settings. Why it isn't working that way I don't yet know, but it looks like my next task is to test the input to Q16 with an LED and see if I am getting a signal there which changes with conditions.
Plugging an LED into the space for R57, I find that varying the rpm does cause a change in the intensity of the LED and switching off the stim tach signal causes it to go out. The interesting thing is that the (extra) ign LED on my stim operates in reverse fashion, indicating that Q16 is probably inverting the signal and this makes sense considering that Q16 is sinking to ground but it is too bad it didn't work out the other way as it would have been handy to have an increased level of interchangeability between units and vehicles. Oh well. I suppose there is a way to do that but probably not with this transistor, unless it could be done by simply removing R43 and allowing Q16 to function as a diode. Probably nothing to be gained by doing that but the transistor is installed...
Nope, all that does is leave the Ign LED on all the time so apparently the junction is going the wrong way for it to work. However I can now bridge the leads of Q16 and get the desired results, meaning that if at some future time I want to use this controller to directly drive a coil I can simply unbridge Q16 and resolder the lead of R43 and it's good to go.
-
jsmcortina
- Site Admin
- Posts: 39614
- Joined: Mon May 03, 2004 1:34 am
- Location: Birmingham, UK
- Contact:
How does your method compare to the one in the manual?
James
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".
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".
-
Jim Blackwood
- Experienced MS/Extra'er
- Posts: 252
- Joined: Thu Jul 29, 2004 6:31 pm
- Location: Gunpowder Rd
Funny you should ask James. A bit more involved and drawn out to be sure but in the end it is the same in terms of the circuitry, just that the extra components are installed and available for use should the need arise. The intent to isolate the output was not realized, nor was the objective of interchangeability. No doubt a relatively small circuit change could accomplish these things, but not the way I tried to do it, and not being an EE I think I'll leave it at that.