SOLVED ChristMAS Tree trio of LEDs not lighting...

[Feral Feline]

So I didn't have time to build the little MAS Tree dirty-boost until today after dinner.

The audio portion works just fine, but a few LEDs are not lighting up.


For those of you who aren't familiar, this little PCB Christmas-Tree ornament has a little chip that randomises a bunch of LEDs to light up at different times. The LEDs are set to light up in groups of three, and I've got three LEDs not lighting, so I'm guessing it's a power related thing as I doubt I'd have three different coloured LEDs that are duds.

I've reflowed every joint of LEDs and resistors, but it's late so I'll have to continue this shoot tomorrow and will post some more photos then. Having trouble with the phone not connecting to the forum right now...



There we go, now it's working again. Right! Managed to get a shot when they're all lit (except for the troublesome trio).
The painters tape with arrows shows the unlit bulbs.

Pics of the components side tomorrow...

 

[Feral Feline]

Here's the durned thang.

No, I haven't cleaned it yet.


So any helpful hints on where I should chase down the bugs? Replace the three LEDs?

 

[BuddytheReow]

What IC is that? Hard to tell from the picture. I made a LED chaser circuit which was pretty cool but one of the LEDs didn’t light up. It was at the end of the “chase” line so it wasn’t that big of a deal. Turns out one of the pins of the CMOS 4017 wasn’t firing off.

 

[Feral Feline]

What IC is that? Hard to tell from the picture. I made a LED chaser circuit which was pretty cool but one of the LEDs didn’t light up. It was at the end of the “chase” line so it wasn’t that big of a deal. Turns out one of the pins of the CMOS 4017 wasn’t firing off.

IC is an ATtiny13 microcontroller. I've wiggled and jiggled it; I'll try taking it right out and re-insert it with a tweak to the legs. I don't think the IC's the issue, given that so many other LED-trios on the tree are lighting up.

Full-Deets on the Tree are here:

Tree Boost - Guitar Pedal Christmas Ornament

mas-effects.com

&

GitHub - mstratman/xmas-pedal: Guitar pedal Christmas ornament

Guitar pedal Christmas ornament. Contribute to mstratman/xmas-pedal development by creating an account on GitHub.

github.com

Audio circuit is by Joe Gagan, Nine Volt Nirvana's Tape Measure, a dirty boost.

 

[spi]

From looking at the schematic, I doubt it's power related, because the power goes directly to each set of LEDs.

The power path goes through the 3 LEDs, and the transistor acts as a switch to ground. The signal from the IC to the base of the transistor will turn it on or off. You should check if the pin of the IC as well as the base of the bad batch is seeing signal turn on and off. If its not then it might be the chip.

Also check the soldering for the LEDs and CLR for the bad batch, as well as the resistor between the IC and the transistor.

 

[KR Sound]

According to this, those three lights are in the same group (Orange). That’s gotta mean something’s not connected right with them.

 

[benny_profane]

I think that one of the LEDs in the ‘red’ grouping may be damaged. The 3mm LEDs can melt very easily when mounted flush to the board.

 

[KR Sound]

I think that one of the LEDs in the ‘red’ grouping may be damaged. The 3mm LEDs can melt very easily when mounted flush to the board.

Ya, I’d say replace them and see if it works.

 

[Coda]

What are your collector voltages on the transistors? Also, are you sure the BBD’s are legit? Have you tried a buffer in the chain?…

 

[Feral Feline]

Transistors are all oriented correctly, solder joints on transistors look good.

I tested the three LEDs individually with some leads hooked up to a watch-battery, working from the bottom up:

Bottom Right: lit
Middle Left: lit
Top Middle: darker than my heart

So I carefully eased out the dud green-LED a bit at a time so as to not rip the pads out of the board, used the super-sucker to clean out the pads of any remaining solder, tested a green-LED, soldered it in, tested it again with a watch battery before cutting off the legs and it was still good, added the battery back to the tree and flipped it on:



Many thanks to all for your help.