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hello
I just finish the mounting of PCB, without personal changes.
I tested the operation with a 7.4V 900mAh LiPo battery and a 9V power supply 2.5A
I have nothing on the display, no minutes, no hours, no colon
I press on “DET” I have a countdown of 10 seconds and all the led flashes in addition to the buzzer at the end of the countdown
if I kept the button “DET” pushed, and press four times on “MINUTES” countdown lasted about 16 seconds
but still no display
i check all chips and no problem
In addition to this problem more than annoying, I find the controller very hot and very quickly
i give you some pictures of PCB if that help you
(clic for zoom)
I see the problem. You put the chips in the wrong places. The 74HC595 is supposed to be on the left, and the 74LS247 is supposed to be on the right. The chips are not the same! The chip numbers are printed on the silkscreen so that it was clear.
The regulator is hot because the circuit is shorted in the chips. They are probably damaged.
Perhaps you will be able to unsolder the chips with some solder wick. If you have access to a hot air gun, that will be best. Difficult problem….
Best of luck, my friend. It happens to the best of us. Last weekend I fried a $40 XBee radio by hooking up 9V instead of 3.3V.
ok, i replace chip at the good place
now display locked to 00:00
if i try to modify time or alarme i don’t have change on display but PM led turn on some time (i deduce clock program work)if i starrt countdown, and try to defuse (cut wire) that’s work, but display stay lock on 00:00
The 74LS247 chip is almost certainly fried. Perhaps the 74HC595 is also damaged. These chips are not expensive. I’m sure you can get a 74HC595 in France, and maybe the 74LS247. If you want, I can send you replacements if you pay for the shipping ($15 USD). Send an email to me to make arrangements.
i try to search chips in france (i have some other component to buy)
if i don’t found it here i email you, thanks a lot
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