That 2am service call taught me to double-check transformer voltage before swapping panels

Customer in Wichita had a Vista 20p showing garbled keypad, turns out someone put a 16.5V transformer on a panel that needed 12V and it killed the CPU, has anyone else run into mismatched power on Honeywell panels?

3 comments

3 Comments

keith_rodriguez7d ago

Different take here - that 16.5V isn't what killed it. Vista panels can handle some overvoltage just fine, it's the continuous 16.5VAC that cooks the voltage regulator over time, not one quick hit. Seen plenty of 20p boards run on 16.5V for years before the regulator finally gives up and sends 18VDC straight to the keypad bus, that's what really fries things.

derek65611d ago

Did you pop the magic smoke out of the panel?

willow11411d ago

Haha "magic smoke" - yeah I let it out on one of those Vista 20p panels a few years back. I put a 16.5V transformer on one by accident and got the exact same garbled keypad issue. It was in a rental property and the owner had swapped out the transformer without telling me. I mean I should have checked but I just assumed it was right. Fried the CPU so bad the keypad was just showing random symbols. Had to replace the whole board.