VEMS Community Forum
Technical => Triggering => Topic started by: SPatrickB on October 02, 2014, 01:50:37 pm
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Just populated my new v3.8 with ignition and injector drivers. Also flyback, map signal and rs232 wiring back to EC connectors is done.
I plugged it into the loom and uploaded config. It seems okay with comms, etc, but it doesn't appear to see the VR primary trigger signal or Hall cam sync secondary trigger either when cranking. Also, FET outputs for fans and fuel pump don't work, even in test mode.
I plug the v3.6 back in and everything works again.
Any idea what could be wrong with the v3.8 I/O?
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Hello,
Check the connector pins?
Their definition may have changed from3.6 to 3.8. You should have a sheet telling for what each pins are set.
Philippe
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OK, I found that the import of the v3.6 config into v3.8 somehow screwed up the misc output assignment, so my fans and fuel pump were assigned to the wrong (unused, fortunately) channels.
Now all I have to do is work out why I get no trigger signals.
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OK, EU VEMS folk told me that I just have to solder the relevant joints which I had done. The secondary (HALL) trigger is working but still the Primary Trigger (VR) on this v3.8 is missing:
I can see that the trigger circuit in the v3.8 has changed from v3.6 and so I can't get it to work with the usual solder joints:
Can someone please put up a v3.8 schematic so I can try to work out what extra components need to be populated?
Interestingly; I also discovered that my v3.6 is populated differently to the reference image with a capacitor across bottom pads instead of top pads. I need to investigate further to determine if the was adding to the > 3000 RPM noise problem I was getting.
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Did you remove pullup resistor on primary trigger?
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for vr only one solder joint needed, nothing more as I remember
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And remove pull up resistor.
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Here's some images to show the difference in circuits: Blue pcb is v3.8, green is v3.6
(http://i152.photobucket.com/albums/s196/spatrickb/Misc/IMG_4107.png)
(http://i152.photobucket.com/albums/s196/spatrickb/Misc/IMG_4123.png)
The top side of the board looks to be populated the same on both versions.
Which is the pull up resistor?
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After tracing resistance around those pads and through holes it appears to show the circuits are the same, just the layout is a bit different. I am measuring ~30% higher across a couple of them, though I don't think that's significant.
It's almost as if the signal is not coming out of the LM1815.
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And remove pull up resistor.
which one? 18k? never removed it and never had any problems as much I remember
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Here's some images to show the difference in circuits: Blue pcb is v3.8, green is v3.6
(http://i152.photobucket.com/albums/s196/spatrickb/Misc/IMG_4107.png)
(http://i152.photobucket.com/albums/s196/spatrickb/Misc/IMG_4123.png)
The top side of the board looks to be populated the same on both versions.
Which is the pull up resistor?
circuit in you pictures are for secondary hall trigger
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Ah, OK. It's just that a couple of those empty through holes have the primary VR signal at them.
So, it is strange because the components around the LM1815 look the same on both boards. Perhaps that chip is dead?
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This has popped up on VEMS.hu about v3.8 changes:
Input-trigger circuits unchanged (input-trigger circuits component layout same as v3.6). By default primary trigger VR pullup resistor slightly weaker than before: R30=27k (not 18k) which allows signal detection for those VR sensors that have high resistance and low input signal (an otherwise unfortunate combination). Easy to apply stronger pullup when needed (eg a 47k pullup resistor to +5V: internally or externally), eg. for strong, but somewhat noisy VR signal
My VR pickup is noisy, very low impedance (~75 ohms) with strong signal (1.22V when cranking), so looks like I will change R30 to 47K or more.
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What I don´t understand is why can´t we organize this in software or at the very least with jumpers?
This soldering here and there is just annoying and useless.
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What I don´t understand is why can´t we organize this in software or at the very least with jumpers?
This soldering here and there is just annoying and useless.
yes, we need v4 board :D
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I changed the resistor but still no signal which I kind of expected since I should have seen at least some sort of signal with the original resistor.
I'm at a loss as what to do next.
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have you soldered solder joint near lm1815?
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Yes, I had soldered SJ6.
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This has popped up on VEMS.hu about v3.8 changes:
Input-trigger circuits unchanged (input-trigger circuits component layout same as v3.6). By default primary trigger VR pullup resistor slightly weaker than before: R30=27k (not 18k) which allows signal detection for those VR sensors that have high resistance and low input signal (an otherwise unfortunate combination). Easy to apply stronger pullup when needed (eg a 47k pullup resistor to +5V: internally or externally), eg. for strong, but somewhat noisy VR signal.
The more I read this, the less it makes sense. It suggests increasing resistance from 18K to 27K to weaken pullup, which seems correct. But then it say to increase resistance more to 47K for stronger pullup. I don't get it. Instead, decreasing to perhaps 4.7K would make the pullup stronger, IMO, right?
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You may have look to the LM1815 datasheet. I understand that the chip operates depending on the input peak to peak levels and thus on the mean value of the signal as given by the voltage divider R30 | R37 // internal sensor resistance.
For the signal detection problem, you may need a (cheap) scope to solve it (I use bitscope)
Philippe
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It suggests increasing resistance from 18K to 27K to weaken pullup, which seems correct. But then it say to increase resistance more to 47K for stronger pullup. I don't get it. Instead, decreasing to perhaps 4.7K would make the pullup stronger, IMO, right?
It doesn't say replace 27K, it says add 47K.
If there is already 27K, adding 47K in in parallel makes 27||47 = 17 K = stronger current = stronger pull-up.
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OK, I swapped out the 75K I had put in for a 2.7K to give a combined 12.7K (R30 + R56 in series). Still no signal.
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You may have look to the LM1815 datasheet. I understand that the chip operates depending on the input peak to peak levels and thus on the mean value of the signal as given by the voltage divider R30 | R37 // internal sensor resistance.
On both my boards R37 is not populated so there is no voltage dividing happening.
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Discovered that VCC for LM1815 is 1.4V, not 5.x. VEMS.hu said that P259 could be pulling it down but I have not used P259 for anything on this new v3.8 board.
What else could cause this?
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Discovered that VCC for LM1815 is 1.4V, not 5.x. VEMS.hu said that P259 could be pulling it down but I have not used P259 for anything on this new v3.8 board.
What else could cause this?
p259 will be dead :) so remove it and it will start working, or cut p259 power supply leg off :)
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Removed P259 and now nothing works! I have a spare so I will replace it.
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Hello SPatrickB,
If nothing works after removing the p259 then you have found the root cause of your problem, GND connections. Do not replace the p259 before checking all GND's i suspect you do not have GND connected on ec36-pin26 and/or the power grounds available on ec36-pin5/21/22/32 the GND's are not mutually exclusive ALL need to be connected.
If confirmed this is also the reason the p259 broke in the first place.
For suggested wiring of your grounds please follow this diagram as guideline:
(http://vems.hu/vt/help/v3/general/wire_userguide_files/ConnectingPower2.png)
Best regards, Dave
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Right on. I don't know how and I'm not going to pull the loom out and then apart to find out; but somehow sensor ground was no longer connected to ground, only the power grounds were connected. :-[
It's worth noting that I had used the old ground design with the single 20mm long wire between the two. ...Single point of failure....never a good thing in any design.
It's also interesting to note that v3.6 kept running, sans killing P259 and having other weird problems.
v3.8 would not even run the fuel priming on power up but I am now shocked at how quickly it fires when cranking. :)
I'm looking forward to driving and more tuning as it seems a whole different animal now.