I finally got around to assembling the Xprotolab kit I got a while back, and everything seems to be working, boots up to Firmware v. 2.16. When I switch to meter mode, instead of showing 0 volts on both (unconnected) channels, it goes up to a steady 20.47 Volts on both channels
This doesn't change when I connect CH1 or CH2 to GND. When I touch CH1 to +5V it reads 6.7 volts, which is also strange.
I checked all of my connections and they seem ok. I also recalibrated the offset according to the manual, and that didn't help either. Any ideas?
Brian

If you have a multimeter, check the following voltages. If any of the voltages are wrong, there might be a defective part.

• Voltage at +5V should be between +4.75 and +5.25V
• Voltage at -5V should be between -4.75 and -5.25V
• Voltage at +3.3V should be between +3.2 and +3.4V
• Voltage at pin 8 of U3 should be between +2.00 and +2.09V

TIP: If the unit is powered with more than 5.5V, the negative voltage generator would be the first component to get damaged.

Thanks Gabriel,/\r\n//\r\n/I checked the voltages, and the only thing that was outside of acceptable range was the Voltage at -5V, which showed up as positive 0.55 volts on my multimeter./\r\n//\r\n/I've been powering the scope with 5.1v via USB./\r\n//\r\n/Would you have any more ideas on how to narrow down the problem? Or is it definitely the negative voltage generator?/\r\n//\r\n/Thanks for your help,/\r\n/Brian

An update:/\r\n//\r\n/I re-did the solder joint on the TPS60403 legs, since on close inspection it looks like leg 5 (I think, it was the middle of 3) was incomplete. I powered up and re-calibrated, now the meter reads 0.000 on both channels, with slight fluctuations on the order of 0.001V. /\r\n//\r\n/When I touch my finger to CH1 and GND I see fluctuations up to 0.015V /\r\n//\r\n/Would you consider this noise to be within acceptable range, or do you think there could still be a bad connection or component?/\r\n//\r\n/Thanks again for all your help,/\r\n/Brian

Oops, that was short-lived. The voltages are reading strangely again, around 17 volts with a lot of noise. If I order a batch of kits, would you be able to throw in a set of extra switches (I took them off and damaged them while looking for bad solder joints) and a voltage generator? /\r\n//\r\n/Brian