parker_thomas•1mo agoProlific Poster

Had a moment with a 1990s panel that made me rethink my whole approach to troubleshooting

I was working on an old Ademco system in a Tacoma bungalow last month, and for two hours I was convinced the main board was fried because the keypad kept flashing 'FA'. I was about to quote a full panel swap (which, you know, is a whole thing with that old wiring). Then I remembered a forum post from like 2015 where someone said to check the transformer voltage under load, not just with a meter on the terminals. Sure enough, the 16.5VAC transformer was dropping to 11 volts when the system tried to arm. Swapped the $25 transformer and it's been solid for three weeks now. I used to always jump to the most complex fix first. How many of you still run into these old low-voltage power issues that look like a panel problem?

3 comments

3 Comments

lindab491mo ago

Honestly, I usually find it is the board first with those old panels.

oscarw831mo agoMost Upvoted

Yeah, @lindab49, you just changed my mind on that.

daniel59325d ago

Yeah lindab49 I get that, the board is usually the first thing to go. But I remember hearing a guy on an old security forum say that 80 percent of the time those "FA" codes are just a weak transformer, not a dead board. He said most techs swap the panel first because it pays better, but the real fix is the $25 part. I started checking the voltage under load after that, and it's saved me a ton of headache.