I once had to rip VHS tapes from family to digital. I had a VHS deck and a spare laptop with a little RCA plug to USB dongle to ingest content. My first few test rips were awful quality, full of analog noise and weird banding and just unexplainable signal degradation. I couldn't understand, because when I was just playing with the dongle the signal was great.
Eventually it dawned on me: I sat the laptop, right on top of the VHS deck while running the rips. The VHS head ended up directly under the CPU and HDD, such that, CPU and hard drive activity were interfering with the tape reading! I moved the laptop off the VHS deck and everything worked just fine.
Eventually it dawned on me: I sat the laptop, right on top of the VHS deck while running the rips. The VHS head ended up directly under the CPU and HDD, such that, CPU and hard drive activity were interfering with the tape reading! I moved the laptop off the VHS deck and everything worked just fine.