Ring Video Pro Lound Buzz at night

Ring Video Pro Hardwired make a loud buzzing sound at night, quite during daytime. Disarmed and still makea noise a night. Purchased new transformer from RIng since original was 8 years old and maybe not adequate. Noise began when new transformer installed. Cked wiring at main chime (NEW Broan). We have 2 Video Pros and both worked with old transformer except voltage varied fro 13v to 19v depending on day or night. Night caused the low readings and higher voltage during day. Perhaps need to return the RIng Transformer, less than 2 months old? Suggestions?