Odd doorbell failure

[gsurace]

Just wanted to see if anyone else had this issue or an idea on what may be causing it.

A customer of mine has a 2 button doorbell system installed. Standard builders grade, Nutone BK125LWH if that matters. Both buttons are lighted and both were off when I arrived. The transformer was fine so I looked at one of the buttons and when I tightened the terminal screw which appeared loose, BOTH buttons lit up and the doorbell worked fine.

I got a call back the next day to say the doorbell had quit again. I went back to the same button and replaced it with a new one and both buttons lit up again with the doorbell working OK. After about 5 minutes, both buttons go off and the doorbell doesn't work. I have to assume the exact same thing happened on the first trip when I just tightened the screw.

The only thing I can point to as a possible issue is the wiring. Both buttons and the chime are wired with two pair 23/4 Cat5 wire. Not sure who does that but...uh, OK? I am thinking there may be some type of issue (interference?/cancelling?/other random term of your choice?) with the twisted pairs and/or the small wire gauge. The buttons are using the wires from the same pair (orange, orange/white). I am wondering if using 1 wire from each pair (blue, orange) would solve anything.

I can even take this a step further as at each button location and the chime, there is a "spare" four pair 23/8 Cat5 wire. (Yes, all 12 wires are tucked in behind each button!) If interference is the issue somehow, I can take a wire from each cable wire so they are completely isolated.

Any thoughts?

 

[Chamuit]

Have you checked continuity to make sure you don't have a short? Have you swapped out the xfmr in case it is having an issue?

 

[Besoeker]

Is it worth the hassle?
We have wireless front and back doorbells. Programmable ring tones. No wiring. And less than ten bucks apiece.

 

[gsurace]

Yes. I did check continuity and infinite resistance between all pairs that were being used. Recall that the doorbell does work when I replace or reconnect the one button so I'm thinking a short may not be the issue.

I did not change the transformer as the open circuit voltage was OK. Same thought as the possible short, it does work initially and not sure what would cause it to shut down after only a few minutes.

 

[gsurace]

Is it worth the hassle?
We have wireless front and back doorbells. Programmable ring tones. No wiring. And less than ten bucks apiece.

Well aware of wireless doorbells which have a higher failure rate than traditional doorbells and require batteries that eventually need replaced.

Was not looking for options. Looking for how to troubleshoot and correct the issue at hand. This is a very new and very expensive home. Not ready to put in an $7 doorbell in it just yet.

 

[Besoeker]

Well aware of wireless doorbells which have a higher failure rate than traditional doorbells and require batteries that eventually need replaced.

Was not looking for options. Looking for how to troubleshoot and correct the issue at hand. This is a very new and very expensive home. Not ready to put in an $7 doorbell in it just yet.

Mine have lasted years.

 

[Little Bill]

Yes. I did check continuity and infinite resistance between all pairs that were being used. Recall that the doorbell does work when I replace or reconnect the one button so I'm thinking a short may not be the issue.

I did not change the transformer as the open circuit voltage was OK. Same thought as the possible short, it does work initially and not sure what would cause it to shut down after only a few minutes.

I had a similar issue with a Nutone chime kit. I ended up replacing the chime as the coil would not engage. Yours may have an intermittent open and not show up all the time. There's only so much to a standard doorbell/chime. To save you time and headache, I would change out the unit.
Only other thing you might try is to use two wires of the Cat5 per terminal at both the button and coil.

 

[hbiss]

Nothing screams hack like using data cable for other than it's intended purpose. No, there is no "issue" like interference or cancelling, this is a stupid door bell for God's sake. It's possible that there is a intermittent open in the run from the transformer or someplace that affects both buttons. That can easily happen by overdriving a staple or using a staple gun. That's why you don't use data cable as a substitute for thermostat wire.

Another possibility is that there is a poorly made splice buried someplace.

What I would do is use other pairs, as long as you have them, and see what happens.

-Hal

 

[LarryFine]

As mentioned, it could also be the chime solenoid coil. The buttons and bulbs, which are in parallel, are in turn in series with the chime, as with a typical lighted wall switch.

A simple trouble-shooting step would be to move the wire(s) on the 'front' terminal on the chime to the 'rear' terminal, and see whether the issue continues to occur.

 

[kwired]

Are the buttons hooked up in parallel to one another (both controlling the same chime solenoid)?

The one you mentioned is a two solenoid chime I think, and has a "front" and "rear" (one note and two note chime in one unit).

Though I doubt this is the case...if they are parallel to one another, they are in series with the chime solenoid, in parallel possibly not enough voltage across the light to illuminate it? Most will light at pretty low voltage though.

Does chime still work when you press either button when lights are out?

 

[sameguy]

And that's why I have door knocker!
Ok, camera doorbells.

 

[gar]

181004-0858 EDT

gsurace:

You indicated you have at least a voltmeter, because you said the transformer is OK. Make use of that instrument to do your troubleshooting. You should know how to do that.

CAT 5 should not be used for this type of application. It is not a rugged cable. In an expensive home it should be replaced.

You have not described how the circuit is wired. Are separate cables run from each button back to the chime and transformer? Where is the transformer located? Provide a drawing of how you think the circuit is wired, and the layout.

Are the buttons wired in series? If so, then should not work. Does each button go to a different chime? Is one cable daisy chained to the two buttons?

What are voltages measured at different points in the circuit with no buttons pushed, each different button pushed, both buttons pushed, for both working and nonworking conditions? What is transformer no load voltage, and when chime is chiming?

The information you provided is far too little for any remote person to give you much help.

.

 

[Adamjamma]

Cat 5 is run in newer homes sometimes because of how many people want a video doorbell... they then change it after a while to a normal doorbell, or a normal doorbell is installed with the plan to install a video doorbell... my own home has a conduit run in for the doorbell..lol.. ott according to my wife.

 

[hbiss]

No. CAT5 is run because that's what is on the truck and stocking other cables might cost money. :rant:

Don't know what those guys are going to do when CAT5 is not stocked anymore (like CAT3) and replaced with CAT7 or something that is impossible to work with. That's what you get when you borrow from the data world.

-Hal

 

[just the cowboy]

Double up

Double up

Double up the wires. Voltage drop on cat 5 with a door bell only using one set of wires is just asking for headaches in my opinion.

Also tightening one should not bring on both lights if wired front and back, even if both are wired for front one should not light the other unless they end up in series somehow.

What happens when both are pressed at the same time?

 

[Little Bill]

Double up the wires. Voltage drop on cat 5 with a door bell only using one set of wires is just asking for headaches in my opinion.

Also tightening one should not bring on both lights if wired front and back, even if both are wired for front one should not light the other unless they end up in series somehow.

What happens when both are pressed at the same time?

See post #7