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Topic: Problem with my twatch when it's cold! (Read 3091 times) previous topic - next topic

Problem with my twatch when it's cold!

Hi there,

Everytime there is a significant power outage, when I turn my twatch back on, the LCD backlight blinks on and off at about 1 Hz for a few minutes.  After a while, the blinking slows down and eventually, it stops.  At that point, I need to re-adjust the contrast and reset the twatch.  Then it runs without problems for days or weeks until the next time I need to power it down (or power fails again).

That looks like a bad solder, but I don''t quite know where to start looking.  Anyone has an idea what could cause the backlight to blink on power up ?  (Maybe the unit is resetting on every blink, hard to tell since the display is unreadable, but apears to be stuck on the APIPA address, does not get to the DHCP address).


Re: Problem with my twatch when it's cold!

Reply #1
hi yves - that's a new one to me. The transistor labeled NPN1 controls the back light, but it sounds like a bigger problem.

Have you tested it with a different power supply? Maybe the adapter is damaged or weak.
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Re: Problem with my twatch when it's cold!

Reply #2
Ian, you rule!

I tried a different adapter, and bingo, no more problems.

Strangely, the bad one is 10V 1A and the new one is 9V 500mA...  I guess the bad one has a problem...

Anyway, problem fixed!  Thanks!