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Calibration using C3 and C5 not working
Posted: Thu Nov 24, 2016 4:51 pm
by shail
I've followed instructions and checked all voltages for DSO Shell 15001 kit.
I am unable to make a perfect square wave using trimmer c3 and c5 adjustment. Also noticed that test signal voltage level is very high. See the attached picture.
Test signal 0.1v appears as 9v signal. When I change test signal to 3.3V it goes up to 50v
Re: Calibration using C3 and C5 not working
Posted: Fri Nov 25, 2016 3:22 am
by jye1
There might be gain error for the amplifiers. Please check resistors R5, R6, R13, R14, and R15.
Re: Calibration using C3 and C5 not working
Posted: Sat Nov 26, 2016 11:56 pm
by shail
jye1 wrote:There might be gain error for the amplifiers. Please check resistors R5, R6, R13, R14, and R15.
I've checked all resistors again.
R5, R6 is 620k when soldered on the analog board. I've also measured it after desoldering them it those are 1k.
Resistor values
Measured after soldering
R27 : 120
R26 : 120
R16 : 150
R14 : 1K
R15 : 680
R13 : 150
R6 : 620 (if measured after soldering to the board, otherwise 1k)
R5 : 620 (if measured after soldering to the board, otherwise 1k)
R12 : 15
R11 : 15
R10 : 30
R9 : 91
R8 : 150
R7 : 266
Voltage Check
Input : 8.10v
V+ : 7.17v
AV+ : 5.85v
V- : -6.53v
AV- : -5.31v
V1 : 0v
V2 : 0v
V3 : 0v
V4 : 1.44v
V5 : -0.96
Re: Calibration using C3 and C5 not working
Posted: Mon Nov 28, 2016 12:08 pm
by jye1
The numbers look good. Please try factory default restoration as instructed in the manual.
Re: Calibration using C3 and C5 not working
Posted: Wed Nov 30, 2016 2:54 am
by qu1ck
Judging by the picture you have C1 and C4 mixed up. The bigger one (0.1 uF) should be on the right.
Re: Calibration using C3 and C5 not working
Posted: Fri Dec 02, 2016 4:23 pm
by shail
qu1ck wrote:Judging by the picture you have C1 and C4 mixed up. The bigger one (0.1 uF) should be on the right.
You are right, Issue has been fixed
.