EDU09 Calibration Failure


#1

I have just finished assembling the EDU09, loaded the program and ran calibration with the following results:

Calibration results:

CH1 offset at 5V/div : 59 FAIL
CH1 offset at 1V/div : -201 FAIL
CH1 Y-position low 145
CH1 Y-position mid 128
CH1 Y-position high 126

I have a reading of 4.926V on the anode side of the Zenerdiode
IC2 pin readings;
1 - 3.5 to a low of 1.9 I can not get a steady reading
2- .351
3- .325
4- .876
5- 4.76
6- 2.01
7- 2.46
7- .002
It is also very hot!

IC1
1- .327
2- .314
3- .326
4- .250
5- .329
6- 0
7- .90
8- 0
10- 4.863
11- .338
12- .339
13- .320
14- .340
15- .002
16- .002


#2

[quote]It is also very hot![/quote]This may indicate the IC2 is in reverse polarity.
For right polarity, please see:
viewtopic.php?f=46&t=13859


#3

No, that is not the issue, IC2 is in the proper orientation.


#4

OK.
Here are the voltages measured on IC2 pins:
1: 1.56V
2: 0V
3: 0V
4: -5.2V
5: 0V
6: 0V
7: -1.65V
8: 5.0V

These are measured when the USB cable is connected but the PC software EDU09 is not running.
USB connector shield is used as ground reference.
You should get on pin 8 the +5V. It is coming directly from the USB socket of the PC.
On pin 4 there should be about -5V, coming from the charge pump.
For more details please see also this thread:
viewtopic.php?f=46&t=9325

On IC1 pins the voltages should be:
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