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Success x 2!
You narrowed it down nicely Michael, there was a small bridge of solder on the collector lead of the right-most transistor, shorting that side to the ground plane. This was not a section which my son had gouged accidentally however, so I had passed it over quickly on initial inspection.
It seems as if the board house who created your boards may have not gone far enough with their mask? I see how there is exposed areas of the ground plane near many of the pads – easily bridged by improper (or sloppy) soldering technique.
I also found the exact same thing on the PM LED (which, it turns out, was NOT lighting during the “detonation”); after cleaning both issues, the clock works quite nicely.
Thank you for your support! I would be interested in purchasing another version of this kit in the future if and when the solder mask / ground plane issues are made a bit more “kid proof”.
–josh
Success! (Kinda…)
I first measured the resistance between the VCC and GND pins of the LED driver (pins 16 and 8 ) and found it was a dead short – which explains why that poor regulator got so hot.
After closer inspection in and around certain pins, I discovered at the 10K resistor located near the Alarm pushbutton. It looks as if my son may have inadvertently gouged some of the bottom mask and exposed the ground plane below. I re-soldered the one side of the resistor and measured the two pins as above – no more short circuit!
I then plugged in the supply and basked in the glory of glowing red digits….
except 🙁
Not all of them display – specifically the tens place for minutes does not work, nor does the PM indicator LED. The functionality seems to work fine – I was able to detonate the device with the red button and all the LEDS worked at that point.
I suspect my son may have done more damage than just that one section near the 10K resistor.
Would it be possible for me to buy another unit? I’ll assemble it myself and tell him I fixed his at work 😉
