Redox probe calibration.

[tramsden]

Hi
Just bought a redox probe and sat down to read manual to aid calibration. First thing I had no "null plug" so I made one by connecting centre connector to outer as indicated in forum.

When it came to calibration, this is what I did,
Nothing connected went to calibration screen. Via sensor settings > redox 1 > calibration .

Cali. Tolerance <1> pressed return
Calibra. Value 2 220mv pressed return

Then I'm presented with a screen that has a return symbol only, if I press return a calibration starts. I have read that a message should come up indicating that the null plug be connected but I have never seen this message, what am I to do?

P3 ex firmware 5.12

Regards... Tony

[Matthias]

this is a bug in the 5.12a BETA of last week and this has been solved in today's 5.12b BETA

-> please update to 5.12b

please give us your feedback if the problem has been solved with the update

[tramsden]

Thanks..

I've updated to the newest firmware, which reset my controller to factory default complete with German menus, I reloaded the setting & sensor files I had thankfully saved prior to the update.

Now I have the screen prompt to insert the null plug.

Anyhow, I calibrated the probe, all seemed well so I left the probe in the calibration solution but the reading climbed to over 290mv, that can't be right?

I put the probe back in the sump and it now reads -1mv, what am I doing wrong?

Tony

[Matthias]

Does the controller show approx. 0mV when you insert the null plug?

What are the ADC-values (see ProfiLuxControl calibration data)?

[tramsden]

Just inserted the null plug it shows 2mv after 2min +
It appears to be rising now about 5 mins and it shows 6mv +
I assume the + means it not stabilised

Value 0mv ADC1 455
Value 22mv ADC2 476

Tony

[Matthias]

I guess you meant 220mV?

these ADC values are not good, the difference is only 21 - there should be a difference of 200 ... 300

you are sure that the calibration process was correct ? fluid Ok, used the correct port, etc.?

if all was correct a defective probe must be considered

[tramsden]

Ok I'll try another calibration, FYI the calibration fluid is GHL's 220mv opened beginning of week when I received the probe.
The null plug is home made from a bnc to phono adaptor which I wired so middle pin & outer are shorted.

Just to make sure I'm doing it right does it make any difference wether the redox probe is connected before I'm told to connect the null plug or should I disconnect the redox probe now before I even access the menus.

Tony

[Matthias]

than the fluid should be fine

I fear the homemade null plug could be a problem - are you sure it is really shorted?


Just to make sure I'm doing it right does it make any difference wether the redox probe is connected before I'm told to connect the null plug or should I disconnect the redox probe now before I even access the menus. doesn't matter

[tramsden]

Ok I've shorted the pin on the socket itself.
Value 0mv ADC starts at 455 and doesn't move
Valve 220mv ADC 482

Current sump value is 2mv.

When the probe arrived on Monday there was a lot of deposit outside of the electrode cover, maybe it had dried out and this is causing the fail. If you don't have any other suggestions I will contact the retailer and ask for a replacement.

Just as a matter of interest what figures should you expect other than being 200 to 300 apart?
Tony

[Matthias]

clean the probe head carefully with a soft brush and let it in the tank for a few days, maybe it recovers (if it is defective)

ADC values can vary but there should be a significant distance

[tramsden]

I've cleaned with a soft toothbrush.
Surely it must be the probe, the null plug and the socket shorting showed a value near 0mv.