Capacitive Tank Senders

[danbenua]

I'm installing a new 5600 and have Princeton converters for my capacitive senders. My tanks
were half full when I started, and AD values of about 1870. When I drained them to prepare
for calibration I noticed that the AD values had only dropped about 100 units to around 1770.
Is it normal to have such a small range between half full and empty? If not, I would like to
know before I start filling them.
Thx,
-Dan

[Shawn McGinnis]

Which Princeton adapters are you using? Vans / 1SP / 2SP / 5SP? If you cycle power to the senders do you see the AD_VAL go high for one second then low for one second during self test?

[danbenua]

My converters have no external identification, but they were purchased from Van's in 2007. With the converters powered off, the AD values are about 2500. When
power is applied, the AD values increase to about 3700 before decreasing back the the "empty" values of around 1760. The damping is too great to allow
the values to stabilize during a 1 second self test. These AD values are very different from what I saw on my old 4500 which had empty at 0 and full at 700
with these same converters.

[Shawn McGinnis]

Your EFIS may not be setup for capacitive readers. If you disconnect the 37 pin harness from the back of the EFIS does the AD_VAL drop to 0? Or by chance are you using an SV-EMS-220?

[danbenua]

I am using the SV-EMS-220 and I specified capacitive senders when I ordered.

[Shawn McGinnis]

Have you set your Sensor Type to Capacitive? Which of the SV-EMS-220's Enhanced General Purpose Inputs are you using (pins 8, 22, 23 or 31)?.

[danbenua]

The sensor type is set to capacitive, but they are connected to pins 20 and 21 as shown in the installation manual.
These were not changed when I upgraded from the 4500.

[Shawn McGinnis]

If you are a two tank user moving them to 22, 23 would be the best choice.

[danbenua]

So are you saying that the installation instructions are wrong for capacitive senders?

I think there are resistors in the lines to the converters. Would removing them
help. Currently pin 22 is already in use for a flap position sensor, but pin 23 is free.

[Shawn McGinnis]

The AF-5000 manual does not specify anything for an SV-EMS and Capacitive senders.

The inline resistor is not needed with the SV-EMS but will have little effect on the system.

You can move the Princeton to pin 8, 22, 23 or 31. Which ever works for you.