Cressi Edy, fix alarm sound?

[zai.gezundt]

I have old Cressi Edy computer. It worked fine until battery was replaced. After that alarm sound became so quiet that to hear one needs to put the computer very close to an ear. I opened cover to see if any contact got loose but have no idea how it works. I marked three places with red arrows where metal could have contact with cover and added picture of cover itself with white circle glued (?) off-center.

If anybody is familiar with watch construction please let me know if anything can be done to fix it.

Thank you.

 

[dmaziuk]

Buzzers tend to be simple stupid things where noise level is proportional to voltage. Check that your batter is actually delivering 1.5V. Other than that, there's mechanical wear and tear on the buzzer itself, and possibly rot in the solder contacts that adds resistance and therefore the power drops. I doubt there's much you can do about those.

 

[zai.gezundt]

The battery is fresh. Apparently the white circle on the cover is a piezo buzzer. But it is a mystery what kind of signal is required to test it.

 

[dmaziuk]

The battery is fresh. Apparently the white circle on the cover is a piezo buzzer. But it is a mystery what kind of signal is required to test it.

Cool. Presumably whatever voltage comes off of the pin on the left in your photo. ICBW, YMMV, and all that.

 

[DIVEWATCHDOCTOR]

Dmaziuk has a point in suggesting you should verify the battery voltage. However, be aware that the Cressi Edy takes a CR2032, which is a 3V lithium battery. Secondly, "the white circle glued" is precisely the piezoelectric crystal that beeps when an electric voltage is applied to its terminals. If the battery is 3 volts or more, I suggest you clean the three contacts you pointed with the arrows. The most important, and difficult to clean is the spring (the one on the left) which precisely is the one responsible for applying the electric pulse that produces the beep. I suspect the spring makes contact precisely at the "dark and pointy spot" on the piezoelectric crystal, which could also be a likely cause for the low volume. I would recommend you clean the three contacts AND the "pointy dark spot" with a contact cleaning pen: Watch Battery Power Pen Battery Life Saver or an electric contact cleaner such as https://www.amazon.com/Company-300554-Specialist-Contact-Cleaner/dp/B084VP9JJK . But if you use the latter, apply it first to a Qtip and then rub the soaked Qtip against the contacts and the "dark pointy spot". You don't want to flood the electronics of your Edy with W40 contact cleaner.

 

[zai.gezundt]

Thank you for the information, @DIVEWATCHDOCTOR. I will try to clean contacts AND the "pointy dark spot" as you suggested. Actually the spring makes contact at the different location, marked with red circle and battery lock (rightmost arrow) touches cover at the location marked with blue circle:

What is the lifespan of piezoelectric element? Interestingly that one can hear faint sound of alarm even if the cover is removed.

 

[DIVEWATCHDOCTOR]

If the spring makes contact at the red circle, that point and the spring itself (does it come off?) would be my primary targets during the cleaning operation. But then I don't have a clue what could have generated the "pointy dark spot". The faint sound you can hear with the cover removed is probably generated by the internal electronic oscillator connected to the spring contact that feeds the piezoelectric crystal. Good luck with the cleaning and let us know the outcome.

 

[zai.gezundt]

It is possible that spring comes off but I am reluctant to pull it too hard to check this theory. I am also looking for an oscilloscope I can borrow and see if there a signal off the spring at the time alarm sounds. Google says amplitude should be 9-12 V which probably means that there is a transformer coil in the circuitry. Will keep you posted. Thank you.

 

[zai.gezundt]

No signal from the spring during the alarm. But other functions are OK. Well, it will be a silent backup computer. If I won't mess up the gasket.

 

[dmaziuk]

No signal from the spring during the alarm. But other functions are OK. Well, it will be a silent backup computer. If I won't mess up the gasket.

Do you have to push it in to get the signal? There's gotta be something or wouldn't buzz at all and you said it does, only very quietly.