Runs, but trace incorrect

[jmaynard]

After finding and fixing one missing solder joint on J1 on the LCD board, my DSO138 runs fine, except for one problem:

On the 1V range, the trace is all the way at the bottom of the screen. AV+ and AV- are good. With the range selector set to the 0.1V or 10 mV positions (the other switch can be in any position) and the CPL switch set to GND, V1 is 0 and V2 is 1.68V. With the range selector set to 1V position, V1 is -2.47V; V2 is +.697V on the 5V range, -.792V on the 2V range, and -1.61V on the 1V range.

I measured all the resistors before installing, but I'm guessing I got a couple backwards anyway. Any guesses as to where I went wrong?

[jye1]

Please check soldering of SW2 (particularly pin4) and R5. It looks the input of U2B was open when SEN1 switch was set to 1V position.

[jmaynard]

Yup. that did it. Pin 4 wasn't soldered, and pin 1 was not well soldered. Hit them both, and now it works fine. Thanks!