Electronics > Projects, Designs, and Technical Stuff
GeekCreit Rainbow Clock Kit Problems
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OM222O:
I'm not sure since they do not provide any details in the manual you linked. no schematics, no part numbers for the leds, no nothing! without having the circuit in hand, it's impossible for us to tell why. if you say there is only the MCU,the RTC chip and a transistor, then that means the MCU must be supplying all of the current for the leds? that doesn't sound right. the next best thing would be that LEDs are digital as suggested before, so check if they have a connection to the positive supply. another thing you can check is the connection between the MCU pins and the leds. how many pins are connected? are they serial line pins or generic io? there's just too much information missing for us to tell anything.
Websteria:
There’s a lot of small resistors and capacitors on the back. I have another board but I have no idea how to create a schematic from a board. Based on my testing they aren’t digital leds. I’m wondering if the line driving the green leds doesn’t have a cold solder joint somewhere. They’re all wired independently.
Websteria:
Here’s a link to show the problem.

https://youtu.be/c1D23Q4-DPw
Websteria:
Ok. I used my bench power supply to give 5v and 20ma of power. As suspected the green led terminal lit the red led. This means there’s a short between the red and green terminals on one of these tiny leds. I reaoldered all the anode sides with flux (grounds are tied together) with no luck. They’re all in the same circuit so it seems.
OM222O:
a short could be possible. but as I said earlier, instead of trying to find the short by applying voltages / using diode modes, try using the resistance mode.
measure the resistance between one of the green led anodes and:

-The anode of another red led
-Ground
-Driving pin on the MCU

and then post the results.
The first one tells you if there is a short between the green and red leds, the second tells you if the green leds are shorted to ground and the third verifies correct connection between the MCU and the green leds (you should be able to read the current limiting resistor value between the two).
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