Hello
I am 10 years old and I have just finished building my Meggy Jr RGB. When I tried it out with Attk.of the cherry tomatoes still programmed, it behaved strangely. The sound and the buttons are working and the top and bottom led borders are working but the green fighter appears as a faint green line across the middle of the screen and I can't move it. The red cherry tomatoes aren't there at all. Also the yellow 3mm leds aren't working either.
Can someone please help me?!?!
Thankyou, from Ben.

It actually sounds like your Meggy Jr RGB is *mostly* working, we just need to figure out the last few parts. I can probably help you, but you will need to explain what you're seeing more clearly, and have a little patience. Please answer these questions:

1. When you first turn it on, it should show some rainbow colors across the full screen for a moment. Are there any sections that are fully dark?

2. What color are the top and bottom LED borders? Do you see a full border across the whole top and across the whole bottom?

3. Is there anything that you see on the screen besides the two borders and the green line?

Hi. Thanks for trying to help me. I have the answers to your questions.

1. I do not see any rainbow colours come across the screen at all and rows 2, 4, 6 and 7 are all dark.

2. The top border is blue and the bottom border is yellow and there is a full border on the top and bottom.

3. A very faint purple line on row three going all the way across.

Also the green line goes all the way across on row five.
Ben.

Hi Ben,
Those are all clear answers, I have a couple more then, that will help me understand the problem better.

1) Does anything change on the screen, ever?

2) Is the LED matrix correctly oriented with the label on the LEFT hand side, facing towards the up-down-left-right buttons?

3) Is the LED matrix sitting in is sockets correctly?
a) Check that it's not off by one pin in its location, and
b) Check that it's sitting all the way down in place. The pins need to be as deep as shown in part 2 of step 11 of the instructions. (And, ask your dad to help you check this one.)

Hi again. Here are the answers.

1. No.

2. Yes.

3. Yes, pins are all in correct locations and they are pushed as far down as they can go.

Ben.

Okay, thanks for getting back to me with those details.

It sounds like there's some kind of problem LED driver chips. I'm not 100% certain what the problem is yet. The most likely cause (by far) is that there's a bad solder joint somewhere, that's preventing the right signals from getting from the microcontroller to the LED driver chips.

The first place to look is in the lower left hand corner of the microcontroller chip (U1). Carefully inspect the five solder joints on the bottom side, on the left-- the 5 pins on the corner closest to button 'B'. Your solder joints should be clean shiny, and not dry or cracked, and not touching between the pins. You might want to carefully touch up those areas with the soldering iron and a dab of fresh solder, just in case.

If that does not fix it, you will probably need to check the soldering on the LED driver chips.

Hi.
Thankyou very much for your suggestion.
I have resoldered all the pins on U1, U2 and U3 but it still isn't working!
Dad thinks it might be because the batteries are low. We will try and get some new ones as soon as possible. Also, does the solder have to go onto the top pads of the PCB? That could be another reason because not all the top pads have solder on them.
Ben.

>I have resoldered all the pins on U1, U2 and U3 but it still isn't working!

There is *probably* some place between those that still isn't getting a good connection. This is the part where you have to use your eyes very well. Very carefully check the *appearance* of the solder joints at every one of those locations. Then, check for any possible stray debris-- little bits of metal or solder --that might be causing an accidental connection between two pins, or between a pin of the chip and something else (like a nearby hole in the board).

Also, carefully compare your kit to the pictures in the assembly guide, look for anything out of the ordinary-- if anything could be in the wrong place or orientation.


>Dad thinks it might be because the batteries are low.

Possible but unlikely, since you said that the sound is working correctly. Does it sound like it's playing a game ("tick tick tick tick... eventually... you crash"? If so, then the batteries are okay.


>Also, does the solder have to go onto the top pads of the PCB?

No, it should not. The circuit board has plated holes that carry the signals from the bottom to the top.

Hi.
I've worked out what the problem was in the first place; U2 was around the wrong way.
But when dad was trying to get the matrix pins in again he thinks he might have short circuited something with the pliers and something has fried, because before we had sound and the matrix was working like described above, now we have NOTHING. We get the occasional very faint light from the matrix but everything else is dead. We got new batteries and I tested with a multimeter that it was getting full power and it was. Can U2 be damaged if connected the wrong way? What could be happening?
Ben.

Well... that would explain it, wouldn't it.

Yes, U2 can be damaged by putting it in backwards-- it's likely to be broken. However, damage is also likely from desoldering, so at this point I'd recommend acquiring a replacement chip-- contact our web store about that.

If you see *nothing* then there's likely a problem with this chip being broken or a short circuit that was introduced in the soldering and desoldering. You should be able to use the multimeter to test for short circuits-- look for things that shouldn't be connected together but are.