Analog ch.1 incorrect voltage readings, need help

[kivi84]

Hi,
my vems is runing now on 1.2.11 firmware, before was 1.1.96 with the same problem. Launch control is conected to EC18 pin 16 with 2k4 pullup resistor (no internal pullup, +5V from EC36-28). I got stable 5V readings on pin 16 (measured on the pin taken out from the plug), grounds are fine.

So the problem in my case is that, when I turn on vemstune and go to analog input raw , ADC raw CH1 shows only 1.9V (5V measured on the cable)! I can activate LC and it works (activated by combination of clutch pedal and dashboard switch and relays, voltage drops to 0V when I turn it on and back to 1.9V when off) but it dont want to turn off by its own! I need to turn off the engine and turn it on again to get everything back to normal.
LC flag shows "Launch on" all the time. On the other vems with the same config it worked well without any problems.

Any ideas what can be wrong?

log with launch problem
http://rapidshare.com/files/3871044209/v3.3_u006079-2013.06.04-00.44.13.vemslog

log with another vems showing corect voltage on analog input Ch.1
http://rapidshare.com/files/2727565017/v3.3_n003285-2012.05.30-%20wot%20poprawiona%20mapa.vemslog

Best regards
Paul

[kivi84]

I would be really glad for any help or ideas what might be wrong, or what I need to repair in my wems.

[Sprocket]

EC18 pin 16 is channel 5

Channel 1 is not normally connected on a standard Vems box. It is internal and connected to opamp 'Diff B' which is maybe why you can see the voltage you do.

EDIT!!

The above looks to be for older versions of V3. The latest version suggests that EC18 pin 16 is indeed channel 1. That said, channel 1 on the V3.6 is still on Diff B. Try a different channel number on EC18 pin 2, 3, 6 or 12, channel 5,2,6,7 respectively all of which appear to be pull up to 5v.

[brieken]

i have the same problem with channel 1 on v3.6 vems. This is the ony channel without a pull-up. And I need an input without pullup. Why make an input that is not useable??? The voltage readings from vemstune are different then from the multimeter. now what?? open up the vems unit and remove a pullup from an other input is the only option?

[VEMS]

Hello Boris,

Analog channel 1 does not have internal pull-up but true there is an internal amplifier on-board, this is however normally disabled in Hu factory when the output channel is routed to an ec18 pin by removing a single (10k, r105 ) resistor. If this resistor is still present in your case removing will solve your problem with ch1 voltage offset.



I have included a picture of the board section with the resistor highlighted in yellow circle, make sure your wire going to ec18 is connected to the blue pad in the circle afterwards.

Best regards, Dave