Edu09 Calibration error

I just bought edu009 and i have a problem with calibration… I have checked all soldering and it seems ok.

It sais calibration failed with this error

CH1 offset at 2V/div : 77 FAIL
Rounds : 51
CH1 offset at 1V/div : -46 OK
Rounds : 51
CH1 Y-position low, CH1_DAC1 255 0
Rounds : 33
CH1 Y-position mid, CH1_DAC0 255 77
Rounds : 51
CH1 Y-position high, CH1_DAC2 255 173
Rounds : 51

Hope someone can help me fix this

Hello @NEMANJA ,

Can you please upload clear or high resolution pictures of both sides of PCB
(Component and solder side). This can help to locate the problem.
“In most cases the problem has been bad soldering or solder bridge on the board.”

There have been several similar cases discussed in the forum:

Your calibration results may indicate that “the charge pump” is not working.
If this is the case, there is no -5V on the board.
As a first test, check the voltage on pin 4 of IC2.
There should be about -5.2V.

If not, check all the voltages of the charge pump.
In this thread there are instructions and voltage values:

If -5V is OK, then check the voltages on all pins of IC1 and IC2.
Here are the voltage values:

Also check IC2 orientation.

In the following threads there are some examples of about similar problems and solutions:

Hope this will help you further to solve the problem

Best Regards,
Velleman Support

Ok i did all that and here are the results:

PIN 4 IC2 -5.25V is OK

A 1.69
B 0.45
C 4.41
D 3.02
E -2.6
F -5.25

1: 1.75V
2: 0V
3: 0V
4: -5.25V
5: 0V
6: 0V
7: -1.69V
8: 5.07V

1: 0V
2: 0V
3: 0V
4: 0V
5: 0V
6: 0V
7: -5.25V
8: 0V
10: 0V
11: 0V
12: 0V
13: 0V
14: 0V
15: 0,04V
16: 5V

I have sent you link to hi resolution images.
Best regards, Nemanja

All the voltages seem to be OK.
I’m sorry, there was a mistake in the link of the instructions:
The voltages listed are measured when the USB cable is connected and the PC software EDU09 is running.

As the next test: Please check the voltage on pins 2 and 5 of IC3.
Should be same as on pin 1 of IC2 (about 1.6V when EDU09 software is running).

There on the bottom side of the board seems to be something like solder flux residue.
If you used solder flux, you have to clean the board carefully.

I have cleaned the flux carefully.
Pin 1 of IC2 - 2.45V
Pin 2 of IC3 - 0.00V
Pin 5 of IC3 - 0.22V
0.22V comes to R3 and 0.00 goes to Pin 2 of IC3…

The voltages indicate that the pin 2 of IC3 may be short circuited to GND.
The short may be between the solder point of R3 and the ground plane.

possible short

It was shorted, you were right. Thank you very much for your patience and assistance. Have a nice day. Best regards.

No problem. Glad to be of assistance. Have a nice day and enjoy your EDU09!