How Do I Replace Piezo Buzzer

[boblalux]

How do I replace piezo buzzer
My Timex Expedition has an alarm and hourly chime/buzzer.  It is sometimes weak, sometimes strong, spometimes does not work.  It's possible that I damaged it when writing the battery change date on it!!!
I have a couple of spares and so wish to know....
How to attach?  To get a good electrical contact, I presume I should clean out the old piezo, press the new one in the same position, at the same time putting a 'ring' of heated shellac around the rim of the piezo??
I understand, that before fitting the new buzzer, I can test it by connecting it to an AC source such as the output leads from  an earphone, and turning up the volume control (?)
Thanks in advance for your help.

[clockboy]

This site might be able to help.

 

http://timex.digidep.net/manuals/

[boblalux]

This site might be able to help.

 

http://timex.digidep.net/manuals/

Thanks, a Timex site new to me, Unfortunately, my 2x Tthese dates!!!ime were manufactured in 2007 and 1999 resp.  I've found infos/catalogues etc for dates before, and after!!!

[boblalux]

Sorry, the spelling slipped: "

Thanks, a Timex site new to me, Unfortunately, my 2x Timexes were manufactured in 2007 and 1999 resp.  I've found infos/catalogues etc for dates before, and after these dates!!! "

[JohnR725]

Do you have replacement disc? I doubt writing on it would've damaged the disc unless you pushed really really hard. In order to work it has to have two solid contacts Electrical contacts. So the contacts are on both sides of the disc the side pressing against the back is epoxied On this is a conductive epoxy for electricity. It has to make good physical contact the back serves as the speaker otherwise you're not going to hear very much at all unless is bonded tightly. The other contact the front side is usually a little Gold spring which falls out when the batteries changed. I can't quite see one in the picture? So if you're not making good contact with the disc worst-case no sound poor sound so you have to make good contact. Then whatever's making contact with the silver part of the disc if it makes too much contact you'll scratch the silver off that's a problem also.

 

Replacement involves you getting a new disk if you can and conductive epoxy. I would tend to say it's impossible, except there's a seller on eBay right now selling discs for exactly this. Perhaps if you ask nicely they will tell you how you're supposed to do it. More interesting though is one of the discs is for Seiko in a Seiko package. So if Seiko sold replacement discs there would've been a way to change it and that would be in one of their manuals if we knew the part number and the watch it's supposed to go in.

[boblalux]

Do you have replacement disc? I doubt writing on it would've damaged the disc unless you pushed really really hard. In order to work it has to have two solid contacts Electrical contacts. So the contacts are on both sides of the disc the side pressing against the back is epoxied On this is a conductive epoxy for electricity. It has to make good physical contact the back serves as the speaker otherwise you're not going to hear very much at all unless is bonded tightly. The other contact the front side is usually a little Gold spring which falls out when the batteries changed. I can't quite see one in the picture? So if you're not making good contact with the disc worst-case no sound poor sound so you have to make good contact. Then whatever's making contact with the silver part of the disc if it makes too much contact you'll scratch the silver off that's a problem also.

 

Replacement involves you getting a new disk if you can and conductive epoxy. I would tend to say it's impossible, except there's a seller on eBay right now selling discs for exactly this. Perhaps if you ask nicely they will tell you how you're supposed to do it. More interesting though is one of the discs is for Seiko in a Seiko package. So if Seiko sold replacement discs there would've been a way to change it and that would be in one of their manuals if we knew the part number and the watch it's supposed to go in.

Thanks, John,

So the back of the piezo must have a good physical contact with the watchcase?  No need for an airgap to permit vibration of the piezo diaphragm?

In my Timex watch, the caseback doesn't act as one of the electrodes, both electrodes are 2 independent springy electrodes.  I have bent them a little bit upwards, and the problem seems to be resolved.  Nevertheless, I would like to know the fitting procedure, in case I have further problems. Have already purchased 4 piezo elements from eBay.  What about shellac, epoxy, super glue?  With the first 2, I could incorporate an air gap, using super glue, not.

Never seen any mention of the voltage range acceptable in piezo elements.

Edited November 7, 2015 by boblalux

[boblalux]

I attach the photo again, with the electrode springs marked.

Bob

[boblalux]

I said above, <<  the caseback doesn't act as one of the electrodes >>   Not true!! It does.  Sorry for the error.

Bob

[KOwatch]

It looks like most of the peizo discs sold on ebay are mounted/glued on slightly larger copper discs (They look brass to me but ok). Some come with pre-soldered leads, one lead is connected to the peizo element, the other to the disc. In many watches, the ceramic disc is glued directly on the caseback which functions as one of the contacts.

I've got an older (70s/80s?) watch here with a cracked peizo that wants replacing. On closer inspection, there's a 20mm peizo element glued to a 27mm (stainless?) steel disc, where that larger disc serves as the second contact. This whole thing is glued into the caseback. I can chip away the ceramic element, I'm not sure if I'll be able to detach the larger disc, it's in there pretty good and there's no way to get it out really. Could try a soak to dissolve the glue with acetone maybe.

The elements are pretty thin, I'm hoping I've got room in the case to just glue another element over top.