Electronic Alarms and Home Security Devices - Ademco 4110 no power

I have an Ademco 4110 installed in the house. I have lived here about 4 years but never used the system. When I bought the house the previous owner did have monitoring, so I know it all worked. Even after we moved in the power on the keypad stayed on and the motion sensor would flash a red light when someone walked by. About a year ago or so the keypad no longer had any power. Just this week I bought a new battery and new transformer, the system is about 12 years old. I installed both yesterday but still no power. I got out the trusty multimeter and started testing the panel. I have power between 1 & 2 where the transformer runs into the panel. I do not however have any power between 4 & 5 (the red and black wires) which according to the schematic is supposed to power the keypad. I'm at a loss here. The fuse is still good and the battery is brand new. Any help or suggestions would be greatly appreciated. Sorry for the long post.

If you have 16vac coming in, but you aren't getting DC power _and_ the fuses check good, then the only thing that remains is a failed motherboard.

Well something sketchy is going on with it. Last night when I checked I had power between terminals 1&2. Tonight I do not. I have power between 1 and everything else. 4&5 still have no power. I have a company coming out tomorrow that is supposed to see if they can get it working. If the tech can get it up and running, no charge and just monthly monitoring after that. If not they wan't 400.00 for new system and I'm not obligated to do that if they can't get it working. What would a new motherboard cost and where could I find one? I could replace it myself. Or would just springing for a new system with another company be a better option. I have had a few quotes for new systems for a low as 199. Thanks again for your help.

You can reliably find a Vista 15p kit with a 6160 keypad (needed for programming) for about $160-180 from many online vendors. The control and keypad without the rest of the kit runs cheaper.

Testing from terminal 1 to any other terminal is meaningless. That's the AC side of the system, everything else is the DC side of the system. What I would guess to have failed is the rectifier circuitry that converts the AC to the DC the system needs to operate.

The second law of thermodynamics wins again.

You were correct. The motherboard had gone out. The installer came out this weekend to set me up for monitoring and couldn't get it to work either. He ended up just changing out the motherboard for free for me and everything is working great now. Thanks for the help.