Calibrating Denerlle PH Controller 588

[loupgarou]

I bought this set from some guy who never used it (ie: all the items were sealed and unopened.

I am unable to calibrate PH 7, the maximum PH the controller registers as PH 7 calibrating fluid is 5.99 (even after adjusting the PH 4 calibration point)

after calibrating PH 7 point to 5.99ph, distilled water registers as PH 6.8 (I'm using battery water here).

I initially thought it was a problem with the denerlle calibrating fluids so I bought new ones. same results.

What could be wrong?

[loupgarou]

Can I calibrate the probe to ph 6 (ph7 point) and ph 3 (ph 4 point), I assume this is to adjust the curve.

so I set my desired display ph to 5.5 ( actual ph desired is 6.5)

btw: anyone know how much a replacement probe will cost?

I also notice that the instructions state that you can "refresh" a probe by immersion in a KCL solution (order no 1448 ),
can I make my own if I can obtain lab grade KCL powder? exactly what would be the concentration be?

[PeterGwee]

Chris, just dip the probe into the pH 7 calibrating solution and wait for it to stablize before pressing the pH 7 button on the controller. (Don't need to care about the reading..unless the reading you are getting is not stable and keeps moving. If the reading keeps drifting about and does not stablize fast enough, then you would need a replacement probe.)

Regards
Peter Gwee

[loupgarou]

no. only the new model (comfort) does that. the old model needs you to adjust a screw, adjusting that gives you the upper limit as described above.

[PeterGwee]

Oops...then you definitely need a probe replacement. Did you ask the auntie of C328 if they can get for you? Or maybe Petmart?

Regards
Peter Gwee

[loupgarou]

I'm also wondering whether its possible to replace the probe with an ISFET based one. anyone has any idea where to get one as well?

[loupgarou]

confirmed that my probe is faulty by testing it against a working probe