Calibration EDU09

I had some initial problems with the assembly of EDU09. Several resistors were missing in the kit. Resistors R8-R13 were 100 ohm instead of 1kohm as stated in the aassembly manual and in the circuit diagram. I replaced these resistors from my own supply R8-R13 1k. However there was no R23 11k and I replaced it with 10k because 11k is a rather unusual value that I didn’t have.
I now have a problem with the calibration:

CH1 offset at 2V/div : 179 FAIL
Rounds : 51
CH1 offset at 1V/div : 56 FAIL
Rounds : 51
CH1 Y-position low, CH1_DAC1 0 83
Rounds : 51
CH1 Y-position mid, CH1_DAC0 0 179
Rounds : 51
CH1 Y-position high, CH1_DAC2 0 255
Rounds : 32

I have checked the solderings, I am an experienced electronics builder.
Grateful for help

Hello
Maybe you will find some leads in

But have you try using the specified value for R23 ? You may need to try adding a 1k resistor in series to the 10k resistor? (1k + 10k = 11k ?) (or whatever resistors you have that give you cumulated in series, a resistor values of 11k )

Hoping this helps !
Have a nice day !

Hello @Laban,

It’s verry strange that there are resistors missing in this kit.
We do for every prouduction batch of our projects kits a production check: (BOM list) before and after production

But there are 2 types of resistors in this kit. 4 and 5 bands resistors! So pay attention!
This tool can also help: (set tool onto 5 band).

4 bands; regular carbon resistors.
5 bands; Metalfilm precision resistors (blue colored resistors)
The 5 bands in illustration manual are marked with * to pay attention on it.

‰ R5-7: 680Ω (6 - 8 - 0 - 0 -1)* bleu 6 / gray 8 / black 0 / black x1 / brown (1%)
‰ R8-13: 1KΩ (1 - 0 - 0 - 1 - 1)* brown 1 / black 0 / black 0 / brown x10 / brown (1%)
image
‰ R14 : 1K1 (1 - 1 - 0 - 1 - 1)* brown 1 / brown 1 / black 0 / brown x10 / brown (1%)
‰ R19 : 5K1 (5 - 1 - 0 - 1 - 1)* green 5 / brown 1 / black 0 / brown x10 / brown (1%)
‰ R20 : 7K5 (7 - 5 - 0 - 1 - 1)* violet 7 / green 5 / black 0 / brown x10 / brown (1%)
‰ R21-22: 10KΩ (1 - 0 - 0 - 2 - 1)* brown 1 / black 0 / black 0 / red x100 / brown (1%)
‰ R23: 11KΩ (1 - 1 - 0 - 2 - 1)* brown 1 / brown 1 / black 0 / red x100 / brown (1%)
‰ R24: 15KΩ (1 - 5 - 0 - 2 - 1)* brown 1 / green 5 / black 0 / red x100 / brown (1%)
‰ R25-27: 20KΩ (2 - 0 - 0 - 2 - 1)* red 2 / black 0 / black 0 / red x100 / brown (1%)
‰ R28: 75KΩ (7 - 5 - 0 - 2 - 1)* violet 7 / green 5 / black 0 / red x100 / brown (1%)

4 Band resistor:
‰ R3-4 : 100Ω (1 - 0 - 1 - B) brown 1 / black 0 / brown x10 / B Gold (5%)
image

Is it possible to upload hi resolution photo (clear photo) of Solder side PCB (Bottom) and Component side of PCB (TOP).

Best regards,
Velleman Technical Support

1 Like

I like it !

Especially the one which illustrates my suggestion of cumulative resistance in series. :
https://www.digikey.be/nl/resources/conversion-calculators/conversion-calculator-parallel-and-series-resistor

Also, for indistinct colors or for color blind people : a multimeter in Ohm position (resistor measure) is a big help.

Thanks. Have a nice day !

Hi, thanks for the answer.

I measured all the resistances of the resistors in the kit with a multimeter. The number of resistors did not total the correct number in the manual there were fewer resistors.

There were no 1k resistors in the kit and instead six 100 ohm resistors Se attached photo where you can se the pattern on the: brown-black-black-back—brown.

There was no 11 k resistor.

I replaced the 100 ohm resistors with six 10k resistors that I had so that was really no problem. I put a 10k resistor in place of the 11 k resistor as I didn’t have any 11k. If necessary I can series couple that resistor with a 1k resistor that I have It would be difficult to replace a once soldered in resistor .

I attach zippes links to photos of the PC board both sides and a picture of the R8-R13 resistors.

Best regards,

Laban

Please check the voltages on all pins of IC1 and IC2.
Make these measurements when the PC software EDU09 is not running.

The voltages on IC2 pins should be about:
1: 1.56V
2: 0V
3: 0V
4: -5.2V
5: 0V
6: 0V
7: -1.65V
8: 5.0V

On IC1 pins the voltages should be about:
1: 0V
2: 0V
3: 0V
4: 0V
5: 0V
6: 0V
7: -5.2V
8: 0V
9: 3.3V
10: 0V
11: 0V
12: 0V
13: 0V
14: 0V
15: 0V
16: 5V

These are my values. I sent them in a week ago, haven’t got any answer
IC2
1 5.00 V
2 -0.572 V
3 0
4 5.23 V
5 0
6 0
7 -1.67 V
8 5.06 V

IC1
1 0. V
2 0
3 0
4 0
5 0
6 0
7 -5.23 V
8 0
9 0
10 0
11 0
12 0
13 0
14 0
15 0
16 5.06 V

These are my values. I sent them in a week ago, haven’t got any answer
IC2
1 5.00 V
2 -0.572 V
3 0
4 5.23 V
5 0
6 0
7 -1.67 V
8 5.06 V

IC1
1 0. V
2 0
3 0
4 0
5 0
6 0
7 -5.23 V
8 0
9 0
10 0
11 0
12 0
13 0
14 0
15 0
16 5.06 V
[/quote]

There seems to be problem only with the voltages on pins 1 and 2 of IC2.
Please check the resistors R25 and R27 are both 20k and soldering OK.
You can verify R25 by measuring the resistance between pins 1 and 2 of IC2.
Should be about 20k.
Also check the resistance between pin 2 of IC2 and pin 12 of IC3.
Should be about 22k.

When OK. Change the value of R23 to 11k (e.g. 10k + 1k in series).

For some reason your response did not appear to this thread.

1 Like

R25 and R27 now both 20k ok. Bwteen pin2 on IC2 and 12 on IC2 22 k, ok
However, between 1 and 2 on IC2 it is 48k

Please check the connection between points marked A and B and also between points C and D marked in this picture.


Point B is the solder point of R25.

If both OK, check the trimmer potentiometer RV1. Should be <2k between the end terminals A and C.

AB connect
CD connect
pot RV1 2.21 k

Seems to be OK.
But if there is still between pins 1 and 2 of IC2 about 48k, this indicates that there may be a missing connection between R25 and pin 2.
Please check the connection 1 to 2 marked in these pictures:
1234

There is a good connection between pin 2 on IC2 and R25 an still about 48 k between pin 1 and 2 on IC2

Very strange…
Please check the resistance between pin 2 (point marked “1”) and point “A”.
Should be about 18k.

52k between pin 2 and A

Is the result same 52k if you measure between points marked “2” and “A”?
If yes, there may be bad solder joint at point “B”.

Yes the resistance is the same. I will check the soldering joint tomorrow and get back.
Thanks so far for your help.

Hello,
I give up. I am very disappointed with the kit. However, let me first say that I have no complaint with the support, you have been very patient and pedagogical. But the kit was obviously faulty from the beginning; missing resistors and several resistors with the wrong value. I do’t know what to do, I am sitting with an unusable product.

I understand your frustration.
I’m very sorry that the fault could not be found.

You can return the kit for repair to your Velleman distributor or direct to:

Velleman Projects Tech. Dept.
Legen Heirweg 33
9890 Gavere
Belgium