Help wiring pH Transmitter (Jenco 695 pH)

ufans · #1 12/21/2007, 05:06 PM

Hi all... Happy Holidays..

I got a Jenco Model 695 pH transmitter and I don't have a clue on how to connect it. I can't find a manual in English either.

The only connections other than the ATC (2 contact) connectors are the Output (3 contact) connectors labeled Neg, Pos, & Gnd. There are no seperate input power connectors!

How do I wire the outputs to a DS2450 A/D converter so I can connect it to a 1-wire network?

How does the transmitter get power?

Please Help !!
UFANS

ufans · #2 12/21/2007, 05:07 PM

Here is a link to the specs for the transmitter

http://www.servonics.com/Jenco693-69...ransmitter.pdf

pista01 · #3 12/21/2007, 08:53 PM

I outlined how I did mine here

Basically the DS2450 must read the voltage drop across a resistor. A 250 ohm resistor will provide a voltage drop of between 1 and 5 volts with an output current between 4 and 20ma. A good transmitter will provide some adjustment of this.

ufans · #4 12/21/2007, 09:20 PM

you the man pista01 ! Thanks for the help... I think I got it now.

The only thing left is to figure out how to adjust the output to get more sensitivity. The problem is that the only manual I can get for the Jenco 695 is in Chinese and translations are rough.

ufans · #5 12/22/2007, 09:28 AM

No luck!

I used a 12VDC power supply, a 220 ohm resistor (that was what I had on hand), a brand new pinpoint pH probe

I couldn't get any change in pH reading whether I put the probe in RO/DI water or Kalkwasser. There should be at least a 3 pH difference, but I didn't get any change on the transmitter.

I verified that the transmitter was operating in full range 1-14pH. I started to wonder if it was because I didn't have a ATC connected, so I calculated the resistance of a ATC probe @ 77F and ended up wiring 300 Ohm resistor as a fixed ATC probe. Still no change in pH.

Any ideas on things to try?

pista01 · #6 12/22/2007, 09:37 AM

Did you try a jumper between the negative and ground? Mine had a jumper already installed. It's used depending on the wiring configuration.

ufans · #7 12/22/2007, 09:43 AM

No, the transmitter has three connections... Can I really connect the negative that is coming from the power supply through the resistor to both the negative and GND terminals on the transmitter?

pista01 · #8 12/22/2007, 09:50 AM

Without the manual it's had to say how it's supposed to be connected. I know on mine I have to add a jumper between the terminals on the transmitter. From what the manual says, there is a three wire configuration that uses all three terminals. When I didn't have the jumper I couldn't get a good reading from the probe.

ufans · #9 12/22/2007, 10:06 AM

No change.

I tried connecting the GND to both the house ground as well as the negative terminal as a jumper.

The transmitter show no change whether the probe is in RO/DI water or Kalkwasser.

pista01 · #10 12/22/2007, 10:21 AM

Did you search through the menus to see if there is anything there? If not then all I can suggest is call Jenco, or try the 800 number in the pdf you linked a few posts up. They probably have a manual in English somewhere. Maybe there is some other wiring config you'd have to use. You can also try looking through the manuals of similar Jenco transmitters to see if they might shed some light.

pista01 · #11 12/22/2007, 11:01 AM

The Chinese pdf I found has a picture indicating DIP switches. Using Google to translate the switch settings makes little sense to me. You'll either have to find the English manual or find a nice Chinese person to translate it for you.

Manual is here for anyone that can make sense of it:
http://www.jenco.com.cn/download/manual/695pH.pdf