Ademco Vista-20P Keypad Shows NO AC


  #1  
Old 09-02-08, 06:19 PM
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Ademco Vista-20P Keypad Shows NO AC

I have an Ademco Vista 20P or possibly the 15P. I recently was attempting to rename my zones and was unsuccessful since I didn't have an Alpha keypad which apparently is required.
During my attempt the keypad seemed to be locked up and would not respond to any keypresses so I started hitting a bunch of keys and now the keypad displays NO AC even though there IS power to the Alarm. I've disconnected the batter and still get alarm function. The alarm seems to function normally otherwise.

Any thoughts on what I could have done?
 
  #2  
Old 09-02-08, 06:28 PM
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You are still in program mode (which may have timed out by now).

If you were fumbling around in menu mode without an alpha keypad, there's no telling what you may have altered.

When all else fails, power down the panel (ac power and battery) wait a minute, and restart.
 
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Old 09-03-08, 08:29 AM
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I tried powering down but no luck. I still have the NO AC message. I have checked voltage and it IS getting power. I've even disconnected the battery to verify power and it still works. Is there some other setting that you know of that might cause a false NO AC message?

Thanks for your help.
 
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Old 09-03-08, 08:37 AM
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I just went into programming mode and then exited and the NO AC message turned to AC. BUT when I open a door it immediately goes back to NO AC. Does this help to narrow down what the problem could be?
 
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Old 09-03-08, 02:43 PM
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Again, since you were blindly keying while in menu mode, there is no way to tell what part of the programming might have been altered until you have a 2-line alpha keypad, like a 6160.

I suspect that you may have changed a zone type to something odd.
 
  #6  
Old 09-03-08, 03:14 PM
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How much voltage is your AC reading? If your one volt below
the required amount, your panel will function but
once in awhile read out no ac.
 
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Old 09-22-08, 08:00 PM
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Update on my problem:

I got an Alpha keypad and I'm still getting an odd error. The display shows AC LOSS. If I go into programming mode and then exit there is no error until I open a door and then I get AC LOSS.

I've checked the zones and they are set to:

Zone 01-Front Door (Main Keypad)- Zone Type is set for 01

Zone 02- Back Door (Secondary Keypad)- Zone Type is also set to 01. SHOULD THIS BE 02 INSTEAD?

Zone 03- Back Door- ZT=03
Zone 04- Nursury- ZT=03
Zone 05- Motion Sensor- ZT=04

Anyone have an idea of what could be screwed up that would produce the AC LOSS message? I definately have AC and the alarm seems to work with no problems regardless of the fault message.
 
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Old 09-23-08, 06:25 PM
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The system will also display NO AC or AC Loss if the system is in programming mode. I cannot figure out exactly what could have been changed to get this effect.

Zone programming generally has nothing to do with either the programming or the power. You may need to look at all of the zones besides the ones you are actually using.

Again, the problem with blind keying is that there is _no way_ to tell exactly what was done without checking all of the system settings line by line.

You may have to simply bite the bullet, default the system and start clean.
 
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Old 09-23-08, 06:52 PM
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How much voltage is your AC reading? If your one volt below
the required amount, your panel will function but
once in awhile read out no ac.
 
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Old 09-24-08, 02:30 PM
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I checked the voltage at the keypad and it is 13.7 Volts.
Is that correct? I did just replace the transformer with an X10 capable model that is supposedly compatible with the Ademco.
 
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Old 09-24-08, 02:40 PM
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The keypad is only telling you that the panel has no AC.
It is not telling you that the keypad does not have
DC. Aux power is DC and should be at 12-14 volts. Now.........AC is coming from the transformer and should be 16-19 volts AC (alternating current). If you are below 16, your panel might
be powered up and functioning, but the keypad might
display NO AC or AC LOSS as you are describing. You need to meter the 1st 2 terminals on the control panel circuit board,
not meter the keypad.
 
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Old 09-24-08, 02:47 PM
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"I did just replace the transformer with an X10 capable model that is supposedly compatible with the Ademco."

If you did this right before this problem started, then my bet would be on a bad transformer. Swap it back and see if the problem goes away.
 
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Old 09-24-08, 02:51 PM
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Make sure your on the right screws on the X-10 transformer.
There are more terminals than the standard transformer.
 
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Old 09-24-08, 06:43 PM
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Okay, I just checked the AC voltage and it's 18.3 at the panel. I also checked the old transformer just for kicks and it also read 18.3 Volts. I have verified that I have wired it correctly so I wonder if I have a bad panel or something.
 
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Old 09-24-08, 06:51 PM
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Which terminal should the RED power wire be connected to?

#1 or #2. The manual shows it both ways.
 
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Old 09-24-08, 07:05 PM
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Terminals 1 & 2 are AC which means there is no positive
or negative such as DC would have. If you metered 18 volts,
I'm not sure why your keypad displays No AC? The only time it would
say No AC is if your in programming, or the AC voltage coming from the
transformer is too low.
 
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Old 09-24-08, 07:08 PM
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Oh, well. Thanks for helping to troubleshoot. I'm pretty sure I exited programming but perhaps you could tell me how it's supposed to be done. I think I hit *99. When I do it, the NO AC actually disappears until I open a door and then it's back.
 
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Old 09-24-08, 08:16 PM
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18 volts is actually too high. This is a 16.5VAC input. Typically if you are seeing 18volts on a system supplied by a rated 16vac transformer, that means that the system isn't actually drawing power from the transformer (there's no voltage drop, the 18volts is the "unloaded" output).

On a guess, you have a bad DC power supply circuit on the V20p motherboard. That it popped up when you tried to alter the programming was coincidental.

It's still actually working, but theres apparently something wrong on the AC detection circuitry.

Unless there's other info we haven't been given, there's no fix for this other than a motherboard.
 
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Old 09-24-08, 08:22 PM
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If his DC circuitry was bad and not producing voltage,
his keypad would not be functioning. I have feeling
there is more to this than he is telling us. Not to
put anyone down or anything, but keep in mind we're
dealing with someone that when told to meter the AC
power from the transformer, he metered power at the keypad.
 
  #20  
Old 09-24-08, 08:25 PM
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Just out of curiosity, why did you install an X10
transformer? Do you plan on controlling X10 devices?
How many wires do you have coming from the transformer
to the panel? Do you know how to program the panel
to control X10 devices?
 
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Old 09-25-08, 01:57 PM
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I installed the X10 transformer in order to control lighting via Insteon devices which respond to X10 signals. As for checking the wrong thing for voltage, I was just not reading your message properly. I was thinking the keypad had the power issue since the alarm panel seems to be functioning fine otherwise.

I have not really gotten to far into figuring out how to program the panel for X10 yet. I enabled it and set the house code but I haven't gotten very far with that yet.

From the new transformer I have five wires going to the panel.

Two power and three that go to the plug that came with the transformer which plugs into the panel. I have checked to make sure those are all wired properly and they look okay according to the manual diagram.
 
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Old 09-25-08, 02:34 PM
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What I am suspecting to be bad is not the actual power supply, but the circuit that monitors the presence of AC power for supervision purposes. (Admittedly, a pretty rare failure, but it fits the symptoms)

This is one of those where I have a funny feeling that something subtle is missing in the information being provided, and our poster simply doesn't know the right question to ask.
 
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Old 09-25-08, 09:46 PM
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Not sure what I could be leaving out but I think that a great clue might be the fact that the NO AC goes away if I go into programming mode and then exit it. The display then appears normal until I open a door and then the NO AC comes back.

This has got to narrow it down a bit, no?
 
  #24  
Old 09-26-08, 05:15 AM
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Personally, I would download a program manual and
learn how to program the panel. Or even read some of
the posts here and there and get familiar how to program
your system. Than go into programming and default the
entire system by entering *97 and start from scratch.
If you still get the NO AC when you open a door, than
either live with it, or buy a new board.
 
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Old 09-28-08, 08:25 PM
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UPDATE: I re-re checked the way I wired in the X10 transformer and found that the adaptor that came with my transformer had the purple and blue wires crossed and thus they were connected to the wrong terminals on the panel. I switched them and the NO AC message is gone.

Thanks for all the help trying to track this down.
 
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Old 09-28-08, 08:31 PM
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Glad you figured it out. Logic told us that it wasn't doing it
before you installed the x10 transformer so I guess
you solved the mystery. Congrats.
 
 

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