Module Tester Calibration

My module tester seems to work fine, but when trying to calibrate using the Offset trimmer, I cannot get the output below 8.38V when it should be 1V.
the gap between v/oct is correct
Help!

It’s not a calibration problem, you have a wrong part somewhere.

Check R6, R10, or maybe the voltage reference.

Does the voltage reference generate -4.096V as it should?

R6 and R10 are correct, which is the voltage reference?

sorry, it’s late the LM4040 is giving out -10.10V

Wrong LM4040? There are different versions available with different reference voltages.

Yes, you’re using the wrong part.

ok thanks, i’ve re ordered the part listed on the bom

You mean the BOM had an error? Or that you’ve now bought the exact part listed on the BOM? Because I confirm that the references published on the BOM are correct. So if it’s a mistake digikey/Mouser/Farnell did when they shipped your order, try to see if they can send you the correct part for free!

I had used a part from a bag labelled LM4040, turned out I had the correct Mouser part still in a sealed bag. I’ve replaced it but now the display no longer works?

the voltage ref now reads -4.11V

but the module tester no longer works

Voltage check?

IC9 got super hot and the power supply died before I had a chance to take any measurements

Then you had a short somewhere…

it was the power cable that leads out to the module, now I have to find another psu, took me ages to find the last one.
Thanks for your help Olivier

Hi,
I have about the same problem. I’m beginner and I’m learning to read the schema. when I’m measuring CV OUT, so i still have a value of 4.35 V, I turn potentiometer as I want.

Oliwerwhite,there are plenty of books for beginners,i was absolute beginners 1 year ago,and now ,with books (how to read schems,electronics for beginners,etc…)its a lot easier!
If you are intereseted to go more “inside” electronic : there is a great book called “the art of electronics electronics” from Paul Horowitz,there are 3 editions.Dont hesitate to buy books its a great help even if you think its not for U ,consider it.Its the bible!

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mutantjf, thank you very much for the great type.