I've got the components in place and 3 rows of the LED's. I decided to light the board
up to see how it would look. Unfortunately the LED's were rather dim. I noticed that
when I would touch the occillator the display would change. The first row would light up
fully and the 2nd and 3rd rows would dim even more.

I decided to try and re-solder the occillator, unfortunately the unit now does not seem
to work at all. I've gone over all of the solder point and I believe they are ok so I am
assuming I've damaged a component (or more).

Any suggestions for what I can test for?

If more than one row of LEDs is lit at a time, that indicates that the CPU (microcontroller) is up and running correctly. If you do not have all the rows of LEDs in yet, you can get some funny excess brightness in some of the rows, as it overdrives the top row. The funny behavior that you saw when you touched the oscillator was the CPU momentarily halting due to extra capacitance from your fingers; this should be expected.

Since it *was* working before you started resoldering the oscillator, I would have to guess that the problem is, in fact, there. Did you fully desolder it, or just add extra solder at that location? Depending on what you did, it may be possible that the oscillator or one of its "helper" capacitors has been damaged. Or, that a trace or via on the circuit board has been damaged, or that there's a bad solder joint, or an accidental short circuit (from too much flowing solder), possibly under one of the components. If you can give me a better idea of what you did, I might be able to help a little more, to point you in the right direction.

Thank you for the reply,

I actually de-soldered the ocillator (using braid wick), and then put it back. It took
a few times to do this so perhaps the heat caused some damage to the area?

I can post a pic later.

Desoldering components is the number-one way that our kits end up genuinely non-working. There are quite a few things that can go wrong, and it will be up to you to inspect things carefully and try to figure out what's what.


* Most importantly, check the soldering in the area. If there's a bad solder joint, or an accidental short circuit (from too much flowing solder), possibly under one of the components, that would be the easiest thing to fix. If you have a multimeter, you can check for accidental connections, and verify the circuit connections that are supposed to be there.

* Don't forget: Make sure that your circuit has power. If you left it on while partly working (or nonworking) batteries can drain.

* Check to see if any of the circuit board traces (the copper printed wiring) has come up, or if the vias (copper plated holes) have been damaged. If so, you may be able to fix it by adding new wires to replace the missing connections. (This is a common thing that can go wrong during desoldering.)

* Check to see if any components are cracked or otherwise visibly damaged. Could anything *besides* the oscillator be damaged from too much heat?

* If all else fails, you may want to try replacing the oscillator (or caps) with new ones, but I would hold off on that until all other avenues are exhausted.

OK, good checklist, thanks!

I will proceed and hopefully post positive results.

I've been doing some checking, in following up on the check list-

-I didnt find any obvious problems with solder joints.

-I'm powering the circuit with the ac adapter

-I did not find any damage to any of the traces. I checked (Ohm meter)
and as far as I could tell things were ok.


One thing I did notice, each of the transistors has 5.2 v coming from the
(multiplexer?) excepting the 3rd from the left which has 4.5 v. This transistor
also has 5.2 v (on the emitter?) on the trace going to the leds

Unfortunately that doesn't add much new information. At this point your best bet would be to try swapping in a known-good chip, and if that doesn't work, to try swapping the oscillator and/or its caps. If you wanted to send it back to us for examination/repair we'd be willing to take a look at it too.

I've ordered the occillator and caps. I try the occillator first.

I'm in a similar position with a Peggy2LE. I had everything lit up fine. All 625 LEDs were blinding bright. The line patterns on power up told me the micro was doing its thing on start up. I was able to cycle through brightness levels. I did notice patterns of dimming or blinking out when my fingers hit the back of the board when I picked it up, but it always went back to playing nice when I put it down.

I suspect the problem was in assembly, though. I absentmindedly put all 25 transistors in backward initially and powered it up. When that didn't work, I figured out what I'd done and put them in the right direction. I'm pretty good with a soldering iron, so I didn't lift any solder pads or bridge anything in the process. And like I said, it lit up just fine once the transistors were facing the proper direction and everything seemed happy. Now it does nothing on power up.

Is there something I could have done by powering it up with the transistors reversed that would have damaged other components such that they would fail after working for a while?

Is there something I might have irreparably shorted out with my hands picking it up?

I have some spare crystals and matching caps, so I can try to replace those first. If that doesn't work, what's next? Should I order replacement drivers/muxes? Or the massive cap?

The most common situation that can cause this kind of thing is a solder joint coming open. This can happen (and does, quite often-- even in consumer electronics) if a joint wasn't very good to begin with and then was stressed by daily thermal changes and/or motion. I'd suggest going through all of the "important" solder joints, carefully inspecting to find any joints that look like they could have come open-- dry, cracked, or blobby ones. You might also make sure that there's power on the board and try wiggling things in various places, to see if you can create a momentary connection-- that would indicate that you're on the right track.