Greetings all! I need to consult you guys for a concern regarding lab bench instrument's a nd laptop grounding scheme. I'm using the laptop (which is a class-2 device, non earthed) together with the Pickit3 programmer/debugger. The Pickit3 is connected to the target ap plication which is powered by an external powersupply. Connected to the app lication board is one oscilliscope and two waveform generators. So, how should I earth all this to prevent anything to burn. Between the laptop "ground" (measured on an USB connector shield)and earth I have about 80VAC when the battery charges is connected to mains. This should be due to some Y-caps in the charger SMPS. The charger has no c onnection to earth so those Y-caps are probably connected between primary a nd secondary ground (laptop ground). I have had the oscilloscope floating, supplied from an isolation transforme r since I've worked on SMPS's lately. But now I rather have it earth connec ted to minimize the leakage current from the oscilloscope SMPS and it's Y-c aps to my application board. So, my question is: Is it safe for the laptop and Pickit3 to connect to th e application board if I earth all the instruments. What worries me is, wil l that 80VAC potential cause any damage to the Pickit3 or even worse, the l aptop? Thanks for your suggestions, and have a great weekend you all!
- posted
10 years ago