P8115'2 Works, but will not calibrate

I have a P8115’2 component tester that seems to work, but does not complete
the calibration cycle as described in the manual? It will read & display components
connected to it. Every time I try to get it to selftest it will read the connected probes, but that is all
it does. I do get the ( 1-O-3-O-2) with the resistance readings, then the screen goes blank!
Am I missing something ?

Hello @jesimu ,

Normally this is the correct calibration procedure:

Before you can start testing components, you will have to calibrate the tester. What you’ll need is a capacitor with a capacity between 100nF and 20µF.
Then follow the calibration procedure below:

  1. Connect the 3 probes together.

  2. Press the button on the tester and immediately press it again if you see “Selftest mode” on the screen. If successful, you should see “R0=”.

  3. When you “isolate Probes” appears on the screen, disconnect all the probes.

  4. When you see “1 -||-3 > 100nF” appear on the screen, connect the capacitor to probes 1 and 3.

  5. After a while, the calibration should end with success.

Best Regards,
Velleman Support

I have done this many times. The “isolate Probes” will appear once in awhile.
The “1 -II-3 > 100nf” only came up the first few times, and I did connect a cap, but
the screen goes blank and I see nothing! Or “Not Calibrated” comes up. BTW: I used a 1uf cap.
No matter what I try, the calibration will not complete.
I’ve tried a few components and the things seems to be working ok! Just will not calibrate, OR is
it only able to run thru the calibration cycle a few times?

Hello @jesimu

Check whether you have connected the correct cables ( 1 - 2 - 3).
Also check all solder points and polarized components.

If all else fails, you can return it to the store where you purchased it for RMA procedure.

Best regards,
Velleman Support

All of my solder joints look better then the best one showing in your example. That is NOT my problem here!. I’ve repeated the calibration cycle many times, I do get the "Version 1.12K testing… 1-0-3-0-2 with resistance readings. 00 ohm and .00 ohm then it sets there. Some of the time it say’s test complete. Or the screen just goes blank ( times out )
Is there REALLY a problem or is it just a programming issue ?? That what it looks like to me?
BTW: Most places that sell kits are NOT returnable!

Hello @jesimu

If all components are correctly placed and soldered, then something is wrong,
especially if the screen goes blank during a calibration.
In this case it seems that IC1 is defective.

You can try to replace IC1: CD4050
74HC4050N can also be used for replacement.

Best regards,
Velleman Support

I changed the CD4050 and I did get it to go thru a calibration!!! Success !!
I managed to find a Motorola MC14050BCP.
Here are the first 2 data screens:
Screen 1:
Version 1.12K
R0=.42 .61 .57 ohm
Ri_HI=26.4 ohm
Ri_LO=22.2 ohm

screen 2:
C0 47 48 51pF
48 53 48pF

These look like calibration values, I hope.
I hope these look like they should.
Thanks for the help, it finally calibrated !!