Analog Discovery Problem?

[Rei Hashimoto]

Hello, 

My name is Rei.

I am using Analog Discovery (Black one).

Recently, I noticed Scope feature couldn’t work.

The calibration was failure also. It showed following error message; “Check the connection!!”

However, the connection is correct.

AWG is failure too. Negative is saturated on the waveform.

I think the hardware is broken.

Please see the picture.

Here is supply voltage;

AVCC5V0 : 4.401V

AVCC-5V5 :1.289V

AVCC5V5 : 5.502V

AVCC3V3 : 3.308V

AVCC-3V3 :-3.278V

AVCC-5V5 and AVCC5V5 are strange.

For checking failure device, the power rail should be separated from analog block. After that, external tracking +/-5V will provide to analog.

Could you please let me know where is jumper.

And if you have any advice, please send it also.

[attila]

Hi @Rei Hashimoto

The +5V5 looks good but not the -5V5

See figure 30
https://digilent.com/reference/test-and-measurement/analog-discovery/reference-manual#user_voltage_supplies1
https://digilent.com/reference/_detail/analog_discovery/int7.png?id=test-and-measurement%3Aanalog-discovery%3Areference-manual

Here you have top and bottom layout with marker parts/pads.

 

 

 

[Rei Hashimoto]

Hi, 

Attila,

Thank you for your advice. 

Here is good news. I removed FB6, 7 and 16.  SC and AWG are well with External -5V regulator. It means that the issue is only negative supply. 

By the way,

The positive supply,5V5 is no problem. On the other hands, AVCC-5V5 is still 0V. The negative supply is generated by ADP1612. Inverted pulse provide from ADP1612 SW pin. And it is only chopping for getting -5V5. D7 and C217 are good. I don't know what's happen on simple circuit. Do you have any advice?

[attila]

Hi @Rei Hashimoto

I don't know where have you measured earlier... Is the -5V5 on C217 ok? Are the ferrites good? D7? L5?

 

[Rei Hashimoto]

I just found out the cause of failure. Please see the picture. Yello : C217, Blue : D7, Anode. The anode waveform seems to be ok. It comes switching. However, AVCCC-5V is wrong. And I checked L5. L5 is completely opened. L5 might be damaged. It should be replacement. I would like to say "Thank you for your help."

 

[attila]

Hi @Rei Hashimoto

I'm glad to hear the problem is isolated. I hope it will work after replacing the diode.