Here is my Supersonic LCD Digial watch. I bought this because I liked the look of it has a look of the Seiko PanAm which is highly collectable. Also because its called Supersonic! It was not working and as I am starting to taking a liking to fixing these I saw this as a good learning experience as it only cost £6.00. The board looks early as its a ceramic board with plastic housing. I stripped the plastic surround off cleaned the board with IPA alcohol with a fibre pen. Removed the rubber contact strips on the LCD and gave them a good clean. On rebuild it still would not work but after playing with the battery retaining spring it finally burst into life. The alarm function runs on a peizo electric principle using a contact from the battery to touch the copper ring on the caseback and with the coiled spring on the plastic surround touching the white quartz centre. when the current is passed through it causes the disc to vibrate harmonically to produce the sound.
Absolutely fascinating considering these were made extremely cheap and caused the quartz crisis in Switzerland yet they have lasted some 30 odd years and still work providing there is no battery leakage.