DSO4254B channel 2 Damaged?!?

Rob_ITA

I was thinking of something. If I remove this resistor can I isolate the AD8510 pin2 input?
If yes, I could do this for all 4 channels I could isolate the 4 points of my diagram.
If there is still voltage difference there then the anomaly could be in the area of my diagram.

Rob_ITA

disconnected the "cuttingResistor" for ch2 and ch3.
Same values as post #27.
I think that the problem is the area of my diagram.

On hex Inverter U33(?!?) :
I=input, O=output

p1 2,39v I
p2 1,41v O -->ch2
p3 2,35v I
p4 1,46v O -->ch1
p5 0,94v I
p6 4,97v O
p7 gnd
p8 0v O
p9 4,97v I
p10 1,46v O -->ch3
p11 2,35v I
p12 1,45v O -->ch4
p13 2,36v I
p14 4,97v (vcc)

Rob_ITA

I've reconnected the 2 resistor.
This is the serial output from some calibration (ended with errors).
(Remove zip extension and open with notepad.)

Rob_ITA

Rob_ITA replied at 2021-1-11 14:49
Waiting for your answer, I inverted U203 between ch2 and ch3.  The problem remained on ch2.  I'll tr ...

Language problem solved editing /config/root/system.inf and restarting.
Changed the value of Lans in 163190. Now I can select between ENG, ITA, etc...

Rob_ITA

When I touch L1302 waveform on ch2 goes up.

Where does the other side of the inductor go?
It ends in a VIA but I don't know where it comes out.

Rob_ITA

Rob_ITA replied at 2021-1-18 02:43
disconnected the "cuttingResistor" for ch2 and ch3.
Same values as post #27.
I think that the probl ...

Maybe I need to lower voltage on p1 to slide down waveform on ch2, but how?
Do you agree?

Rob_ITA

I did as you asked. Left on for 1 hour but it goes into error.
I read do_cal_bias:Try zero ch1 for 7 times.
I think  that at software level the channels are numbered starting from 0 and ch1 is my physical channel 2.
From the serial interface I understand that it is unable to calibrate the gnd on channel 2.

Rob_ITA

And can you explain what does it mean these rows?

get_avg_pkpk_value:-223318,-58, 2, -57, -59
get_avg_pkpk_value:-27043,-7, 2, -6, -8
get_avg_pkpk_value:-219489,-57, 2, -56, -58
get_avg_pkpk_value:-207685,-53, 2, -53, -55
get_avg_pkpk_value:411965,107, 2, 108, 106
get_avg_pkpk_value:488950,127, 0, 127, 127

Maybe

get_avg_pkpk_value: sampleValue,num1, num2, num3, num4

num1 = quantized value on channel 1
num2 = quantized value on channel 2
num3 = quantized value on channel 3
num4 = quantized value on channel 4

??

Rob_ITA

Rob_ITA replied at 2021-1-19 19:15
When I touch L1302 waveform on ch2 goes up.

Where does the other side of the inductor go?

when I apply a voltage to the resistor [01c = 10k] indicated by the blue arrow the square waveform on channel 2 goes down.
Maybe the problem is here.
This is the output of Hex Inverter. Input is coming from fpga U55(maybe).

Rob_ITA

In doing what you asked me, I noticed an important anomaly.
By measuring the resistance value indicated by the yellow arrow I noticed that:
ch1: 170K
ch2: 180K
ch3: 170K
ch4: 170K
I try to measure it after removing it to verify that it is not damaged. The code shows 88D = 806K