Clock Radio locked in 24h mode

Pylon · 08-03-2008, 1:34 PM

Hi, I am new here!
I have always been interested in electronics, and when I was younger I managed to convert a clock radio from 24h to 12h display by linking some pins on the main IC inside.

Well now I have got a tesco clock radio (24hr display) and realising the chip inside is probably less accessible than the one I fixed 30 years ago I was wondering if anybody knew if there was any easy way to get to to display the time in 12 hour mode.

Any ideas?

Thanks
Ian

*avinitski* · 08-03-2008, 1:59 PM

you sure there are no user menus for this?

also is it really worth ripping the thing apart if it cant be done through the menu?
personally i much prefer the 24 hour clock

JagoPlasma · 09-03-2008, 11:52 AM

learn how to use a 24hr clock you cretin

(might have a switch on the back/side though)

Pylon · 09-03-2008, 11:58 PM

It is a very cheap tesco clock/radio, I got for a birthday present!
I only asked here in case anybody knew of an easy fix to get dispaly to show in 12h mode, eg clever combination of key presses, or if there is a link on the pcb I can deal with.

If it wasnt for the fact it was a present, I wouldnt be bothering at all

Sure I can read time in 24h, but more normal 12h is easier for me

JagoPlasma · 10-03-2008, 6:01 PM

was just a joke

if your the kind of person that likes to tinker then tinker!

njp · 10-03-2008, 7:34 PM

If you want to tinker, you'll have to get inside and find out what chip it uses. I just did a quick search and easily found pinouts for the Silan SC8560, which I imagine is widely used in this sort of application. This would be trivial to modify - if pin 28 is connected to Vss (0v) the clock operates in 24-hour mode, if it's left unconnected the clock operates in 12 hour mode. So you could just snip it!

Pylon · 11-03-2008, 8:28 PM

Excellent, thanks NJP, that is the sort of helpful comment I was hoping to find here!
I'll have a tinker inside and see if the chip is accessible.
Thanks again,
Ian

rjs316 · 11-03-2008, 8:37 PM

Are they not set to 24h so the alarm will not go off twice a day?

njp · 11-03-2008, 8:50 PM

Quote:

Originally Posted by rjs316

Are they not set to 24h so the alarm will not go off twice a day?

I would hope that you were also able to specify AM or PM when setting the alarm!

Pylon · 11-03-2008, 9:32 PM

Well it worked!
I cut off pin 28 and also needed to snip pin 1 the am/pm o/p that was connected to some segments on the H10's digit.

It works a treat. Just a bit tricky to set the alarm time without any am/pm indicator though! Trail and error was the only way.

Thanks again NJP, I doubt I'd have bothered if you hadnt given me the part numbner of the IC to start with, it was indeed an (LM)8560!

No, the alarm only goes off once in 24 hours. The am/pm is still functional despite no indication which is which, but I can live with that - I can normally tell which side of the day it is without using my brain, even if I dont like seeing the time as shown as 21:45!

njp · 11-03-2008, 11:39 PM

Quote:

Originally Posted by Pylon

Well it worked!

Excellent!

Quote:

Thanks again NJP, I doubt I'd have bothered if you hadnt given me the part numbner of the IC to start with, it was indeed an (LM)8560!

It was just a guess... I reasoned that the world could not possibly need many different ways of making a basic alarm clock.

Hope you don't miss anything important by setting the alarm for the early evening by mistake...