Trouble with calibration (C5 has no effect, bat test signal)
Posted: Fri Dec 30, 2016 5:35 pm
Hello,
I like the scope, but I have trouble with calibration (and usage).
The testing signal is OK on 3.3V, but the 0.1V square isn't at zero - it has about 3V offset (tested with a Owon 60MHz DSO).
I have tracked the test signal generation to voltage divider (R16 and R31). R31 is rated in the schematic to be 470R, but the SMD resistor on the board is 22R. I don't get where I'd get the 0.1V with 470R or 22R R31 on J8.
Setting input to AC and changing C5 has no effect at all, getting reasonable 0.1V test reading in DC mode isn't possible.
Thanks for advice.
I like the scope, but I have trouble with calibration (and usage).
The testing signal is OK on 3.3V, but the 0.1V square isn't at zero - it has about 3V offset (tested with a Owon 60MHz DSO).
I have tracked the test signal generation to voltage divider (R16 and R31). R31 is rated in the schematic to be 470R, but the SMD resistor on the board is 22R. I don't get where I'd get the 0.1V with 470R or 22R R31 on J8.
Setting input to AC and changing C5 has no effect at all, getting reasonable 0.1V test reading in DC mode isn't possible.
Thanks for advice.