(originally blogged in Feburary 2019)
Hello and thank you for reading my blog post. This post is all about the Trafalgar Talking watch that I bought recently for a princely sum of £14.00 . The watch was completely dead with clear evidence of battery leakage.
The circuit board is quite large and made by Sharp which is a blast from the past to my childhood HiFi equipment. I set about cleaning all the acid off using a fibreglass pen, dipped in IPA alcohol. this got a majority off however I was not satisfied and besides it still did not work! I completely stripped the board out of the case removing the screen and de-soldering the speaker off. This board was going for a bath! basically a hot wash in a jar of alcohol in the ultrasonic cleaner.
Once the board was washed I assembled again but I could still get no life from the module, I checked all the traces for continuity on the multimeter and everything seemed to read normal. Hmmm… what to try next?
So I ended up reflowing all solder joints in case one had become dry. This still proved to be pointless as again it would not fire up. So I then tried another trick I know which is to install the batteries and leave on my radiator in my house overnight. This trick has worked on a few occasions so perhaps this time it will also be a success?
Yes! some sort of life. okay the display is not working correctly but that will just be insufficient pressure on the zebra strip contact. What happens if I press the button?
Wow how cool is that, so 80s synthesised voice. This one will be saved!
Sadly this was short lived and the module soon died again. This lead me to believe that it could only be on the other side of the board with the screen on. I had already inspected and cleaned this side and also reattached a capacitor using some conductive paint which I know was successful from testing. must be another component.
So here is a picture of the screen side of the board, the white capacitor last one on the right at the top is the one I have stuck back on and you can just make out the conductive paint I used.
So this went back on my microscope and with a pair of ultra fine hairspring tweezers I went on the search for the faulty component. My theory is that as it works when warm it could only mean a poor connection so something must be loose. It was not long before I found the culprit, another capacitor. Now there was one problem, I would need to solder this one on and my soldering skills are very much work in progress.
The soldering proved to be quite challenging indeed I could get the solder onto the pads but it would be too much and the capacitor would sit to high. Then in my frustration I had a “ping” moment while holding the cap with my tweezers and soldering iron in the other I squeezed too hard the capacitor went into orbit and no matter how hard I looked I could not find it. Fortunately for me I have spare / scrap modules from other digital watches, I found a cap on another board that looked the same and removed it. With great care and precision I finally managed to get this cap in place and soldered onto the board, it was not pretty so I did not take a photo!
I quickly rebuilt the watch and fitted 4, 393 Renata batteries! turned the module over and got the result I wanted. the display was working correctly and pressing the button I got the time read out to me by the man in the watch!. So here is a clip of it in operation, notice how it fails near the end on the alarm , this is purely due to a low battery. This watch eats batteries!
So there it is, complete. More of an interesting project than a watch that I would wear. I love saving watches and often say that my collection is a byproduct of my hobby which is fixing them. This one presented some challenges and I have learnt a great deal from it. I have also saved this watch for future generations and with the interest in smart watches now this talking watch can kind of been part of that idea, applying the technology of the day into a watch.
Please take time to checkout my YouTube channel “My Retro Watches” as I will be uploading “how to” videos and review videos on a regular basis.
I also have some affiliate links (below) of the products I used on this project so you can check those out and purchase if you need them. I do make a very small commission and all funds raised go to the upkeep of this site and the YouTube channel.
Thanks for reading.