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 2 Rows out on Meggy Jr RGB
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By: Breaking Myself (offline) on Tuesday, December 29 2009 @ 11:43 AM PST (Read 6623 times)  
Breaking Myself

Hey,

I finished my Meggy today (Solder causing no problems, thanks Windell) but I'm 2 vertical rows of LED's out.

Specifically vertical rows 2 and 3 are showing nothing (counting from the left 0,1,2,3) but all other LED's are fine and showing all usual colours. I've looked all over the board for any missing connections or anything that may be causing the problem. It could be my eyes if I have missed something but to be honest I'm not sure what I'm looking for!

Can anyone help me out?


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By: Windell (offline) on Tuesday, December 29 2009 @ 12:43 PM PST  
Windell

First, check to be sure that all pins of the LED matrix are properly inserted into the sockets, to the *full depth* required.

The vertical rows that you are describing are controlled by R4 and R5, driving transistors Q4 and Q5. The socket pins are 9 and 10, (counting down the left hand side. Pin 1 is the upper left pin of the LED matrix socket.) The signals to R4 and R5 come directly from pins 12 and 13 of the microcontroller chip. (Pin 1 is at the upper right, and they are numbered counterclockwise. Pins 12 and 13 are towards the upper left side of the chip.)


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By: Breaking Myself (offline) on Tuesday, December 29 2009 @ 01:48 PM PST  
Breaking Myself

Hey, thanks for the reply.

The LED matrix itself is definately as far down as shown in the instructions, pushed down as far as I can. Whilst re-soldering some parts to be sure I managed to stick my soldering iron against the wire for the battery pack, which broke loose at the base (I'm AMAZING at this kind of thing it seems Big Grin), so I un-soldered it and now one side won't re-solder. It seems the negative side is blocked and keeps giving brown residue when I try to do it. I don't want to go poking around If im going to do more damage than good, it might just be a small amount of wire that won't budge. So even if anything you mentioned helped I can't test it!

I'm sure I'll laugh about this in the future.


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By: Windell (offline) on Tuesday, December 29 2009 @ 02:53 PM PST  
Windell

>so I un-soldered it and now one side won't re-solder.
> It seems the negative side is blocked and keeps giving brown residue when I try to do it.

Do you mean to say that you're having trouble putting the black wire back into the circuit board? You could alternately solder that to the SIDE hole of the external power jack-- the one right next to the transistor.


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By: Breaking Myself (offline) on Tuesday, December 29 2009 @ 03:32 PM PST  
Breaking Myself

Thats exactly the problem, is there any way to clear the hole? Its going to start looking bodged as it is >.<

You mean the part in the top right (looking from the back of the board) with the three holes? In which case its the left hole closest to the transistor, which the black wire will still reach if all else fails.

Fingers crossed when the powers back the LED's will decide to light up!


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By: Windell (offline) on Tuesday, December 29 2009 @ 03:54 PM PST  
Windell

>Thats exactly the problem, is there any way to clear the hole?

Well... there are solder wicks, solder suckers, and the old "blow" method:
http://post.monome.org/comments.php?DiscussionID=2783

(Also see the "pencil lead" method on that page.)


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By: Breaking Myself (offline) on Tuesday, December 29 2009 @ 04:30 PM PST  
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I've managed to get the power on by putting the red wire back and scraping back the brown residue from the black wire hole and holding it in place (temporarily anyway). The LED's still don't show but at least I can test the parts you mentioned earlier.

I had been using the solder pump for re-soldering, which worked like a charm for everything but this one, just my luck!


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By: Breaking Myself (offline) on Saturday, January 02 2010 @ 04:32 PM PST  
Breaking Myself

I still can't do anything with the power on my Meggy. The red lead to the power and the black to the power jack hole doesn't seem to do anything and now the orignal black lead hole doesn't either. I've tried the obvious like the batteries.

I even tried a really small drill piece on the hole to clean it out but it may aswell have been the size of a fist for all the good it did.

I've re-soldered that much and tried to clean up the hole that many times I'm not surprised it won't turn on like "Noooo! Not again!"

Please say there is some way out of this that won't involve a large hammer and me saying "The Russian way should do it!" (I hope people realise, I can be quite sarcastic, sorry!)

Thanks again for being patient with me.


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By: Windell (offline) on Saturday, January 02 2010 @ 05:49 PM PST  
Windell

Hmm.... From your previous post, it sounded like everything was (at least headed towards) under control.

I would definitely *not* suggest using a drill on a soldered hole--things can go wrong.

Do you have a multimeter/voltmeter/ohmmeter that you can use to test for power/short circuits?


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By: Breaking Myself (offline) on Saturday, January 02 2010 @ 06:01 PM PST  
Breaking Myself

I thought the same, I found I couldn't check the other connections or even attempt using the soldering iron if I had to keep holding the wire in place.

I don't have any kind of multimeter, The only thing I could do was to check the batteries still had plenty of charge and thats about it. Only just starting out with electronics, I don't have any special gear from anything else I may have done, as you may have noticed with the soldering question a week or so back.

I may just have to un-solder everything and start again because I just about *nearly swearing* wrecked the PCB and all this messing around, which is my own fault, is just making things worse. Are there any alternate power points for the red and black leads from the battery pack so I can check if theres any life left in the Meggy?


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By: Windell (offline) on Saturday, January 02 2010 @ 07:07 PM PST  
Windell

>I may just have to un-solder everything and start again

This is not an approach that I would recommend; arbitrarily removing components is the number one way that we've seen kits become damaged beyond repair. There haven't been that many steps since you had it basically working-- stop and consider where the problem could actually be. Unless you've managed to actually reverse power to the board at some point, it's likely that everything still works but is not getting power, either through a missing connection or short circuit. If you've bent the wires around enough that they've broken (which is what it somewhat sounded like), then you may have broken wires towards the battery box or something like that.

There are plenty of additional places that you can hook up power; check the circuit diagram. However, the original points should still work, and if they don't, there may still be a problem at those locations on the board.

My advice at this stage would be for you to acquire an inexpensive multimeter to give you better data about what you're looking at. I'm under the impression that you're in the UK (correct me if this is wrong.) Amazon.co.uk has multimeters starting at 2.85 + 2.99 shipping.


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By: Breaking Myself (offline) on Sunday, August 15 2010 @ 09:47 AM PDT  
Breaking Myself

Time to resurrect this thread with some good(ish) news Laughing Out Loud

After having almost given up on my Meggy, I got it out last night and had another go at powering from the original holes and managed to poke a piece of twisted wire from the hole that was previously blocked. With a little 'jiggling' of the wire, I managed to get the power back on and much to my surprise, everything but row 3 was actually working!

After following Windells original solution to the problem, I managed to get all of the rows back in working order.

The only thing causing a problem now is that one of the colours in the matrix seems to be quite dim, possibly blue or green as the red shows up nice and bright. The 'player' dot is a really faint/pale green/blue and when you blast the screen with the left button I get almost nothing, just the sounds and a slight flicker on the screen instead of the bright visual blast. I can record a video or take a pic of the screen if that will help determine what might be wrong.

I still can't get the original power wires to solder in place but I have 'tinned' the ends so they sit firmly in place and will hot-glue them in place when I'm finally finished.

I'm glad I didn't give in, even if it did take me 7 months to open the box and give it another go.


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By: Windell (offline) on Sunday, August 15 2010 @ 04:33 PM PDT  
Windell

I'm glad to hear that you finally got it working.

I'm not certain what the problem is with the LED brightness; it could be a couple of different things. If the red is bright but blue and green are not, it is likely the case that (1) the power (input voltage) is low or (2) that there is a problem at the resistor that sets the current level for the LED driver on the blue and green colors.

In the default game, Attack of the Cherry Tomatoes, the upper and lower walls should be reasonably white in color. Typically they turn yellowish as the batteries become exhausted. Eventually, when the batteries are really *gone* it resets and blinks off during the startup sequence. If this is the case, replacing the batteries, or using a properly specified power supply should solve the problem.

Alternately, it may be the case that resistor R1 is not soldered in place properly, or that pin 23 of U2 is not soldered properly (see the highlighted pins in the attached drawing, which is viewed from the back side of the PCB ). If either of those is the case, then that would explain what you're seeing.

If you can't get the wires to solder in the holes, I may be able to suggest some alternate locations to solder them, but they should *definitely* be soldered. Otherwise, things will fail now and then, at best.

R1!


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By: Breaking Myself (offline) on Monday, August 16 2010 @ 05:35 AM PDT  
Breaking Myself

I'm now all systems go on the Meggy front Big Grin

You were right, it was the R1 resistor that needed a re-soldering (as you can see my soldering 'skills' have been causing most of the problems!).

So everything works now, sound, buttons and 'pixels'. I have soldered the positive wire from the battery pack and part done the negative, it just wont take all over for some reason but the connection seems good and turns on every time. The wire itself isn't very long so I will need to replace or lengthen it, if I end up having to solder at another point.

I will probably line up the top row of led's a little better when I have chance but for now I can get on to the fun stuff, starting to program something of my own >.<

Thanks again for all your help Windell, couldn't have sorted it without your advice.


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