TIL that a bad transformer can mimic a dead panel for hours

I was trouble shooting a Vista 20p at a house in Austin for almost 3 hours, checking every zone and the battery, before I finally thought to test the transformer output. The thing was giving 12V AC but dropping to 5V the second any load hit it, which made the panel look completely dead even though it had power. Anyone else ever chase a ghost problem for way too long because of something stupid simple?

2 comments

2 Comments

adam_butler385d ago

Yeah I spent two hours once swapping a thermostat because I forgot to check if the doorbell wire was shorted.

lisa_bennett4d ago

Flip the breaker first, always. I learned that one the hard way too, just like you. In my experience, it's usually something simple like a stray wire touching the metal plate behind the thermostat. Your mileage may vary, but I always tape off the doorbell transformer wires now just to be safe. Saves a lot of headache later. Take it from someone who's been there, that two hour job turns into a ten minute fix.