I suggest you start with assembling the Matrix LED board because it's easier and then move onto the motherboard. The LED bargraphs are shipped inside special plastic containers that should ensure their safe travel. But sometimes their pins get slightly bent and you need to correct that for them to slide into their place. 20 LED bargraphs are not always in stock at my parts supplier so you'll get 10 LED bargraphs glued together to form a 20 LED bargraph, but that's no reason to worry, they look and function exactly the same.
As you can see from the picture above, both the 10 LED and the 20 LED bargraphs have a marked corner that indicates the Anode. Please use extreme caution to solder them in the right position, because if you solder one in a wrong position it is almost impossible to de-solder it without ruining the board. The correct position to solder a bargraph is indicated in the following picture: note the marked corner(Anode) to the left.
After you've soldered all the bargraphs, you can solder the two pushbuttons, and the 50 pin connector. Depending on the type of board you chose, the 50 pin connector is different and also it's position is different. In the "wire version" the connector is placed on the same side as the LED's. In the "on top version" the connector is placed on the opposite side from the LED's.
After soldering the connector you can move onto the motherboard. As you may of noticed I ship the parts in special antistatic bags to protect them. I never had problems with static, but I heard about atmega's being erased or damage from static so please handle the parts with care. You should start the assembly by soldering the ATmega64. Use extreme caution when soldering the atmega and the other chips. Start by placing it in the right direction, watch for the key that marks pin 1 and watch for the writing on the board and on the atmega, the name should be readable from the same direction on both the board and the atmega. Look at the next picture for a correct alignment.
Next continue with soldering the ULN2003. The name written on the board gives you the correct alignment. Align the name on the board with the name on the chip.
Next, solder the LMC and MCP marked chips. Look into the picture for the correct alignment.
Next, I like to continue with the 1K resistors, the transistors, and the 47R resistors. Their positions are marked on the board, so it should be easy to get them in the right spot. Next you can continue with the 100uF 10v capacitors, there are 3 of these and their position is marked on the board. Next, the 10uF 25v capacitor also marked on the board.
Next, we move into the LMC, MCP chips area. There are some pads and markings around these chips. Well the values have changed since I ordered the boards, so the values marked there are incorrect. Please follow the picture for the correct values that need to be soldered there. Start with the 0 Ohm resistor, continue with 1M resistors and with 10uF and 47nF. Continue with the two 10k resistors next to the RCA connectors. Next solder the third 10K resistor, and 22nF and 10uF capacitors. This is enough for top side at this moment.
Now turn the board over, and start soldering on the backside. Start with the 1K resistors, next the transistors and next the 47R resistors. Next due to an error in the PCB design, we need to add a jumpwire. In the trough hole parts bag, you should find a piece of thin wire that works perfectly for this job. As you can see on the board there is a copper line missing from the emitter of one transistor. That is solved by soldering this jumpwire to it's neighbour. Next two pictures show the location and a close-up of the jump-wire
Next turn the board over again so we can continue soldering on the top side. Solder the two RCA connectors and then the 6 pin ISP header. The 6 pin ISP connector is used for programming the ATmega or upgrading the firmwire. If you don't plan on upgrading the firmwire, don't solder it.
Next solder the DC power connector and the 7805 voltage regulator. On the 7805, I suggest you start by bending it's legs. As you can see in the picture I took, the pins were bended at half of the wide area of the pin. Next place the radiator between the 7805 and the board and fit everything nicely. You might find it difficult aligning the 7805 with it's radiator because the space it's too tight between the radiator and the DC power connector(that's another thing that I didn't anticipated when I designed the boards, but it's not that much of a problem. I manage to get it aligned and I think you will manage too).
Next solder the diode in the correct position(The cathode is marked on the board). Now all is left to solder is the 50 pin connector which depending on the version you ordered can be as follows:
Now you can connect the boards according to the model you've asked for:
The next step is also the final step: connect a 7,5V 1 A power source and an audio signal to the board and the system should be fully functional. Now depending on you signal level the bars should fill more or less. The optimal signal is 200 mV, at this value the bars fill all the way to the top. In most cases computer audio boards can supply more than 200 mV which means you'll have to lower the volume from your computer to allow the bars to come down, otherwise they'll stay up too much and the effect is not nice. You can ask your questions about assembly in this topic and also your suggestions are welcomed.
Useful links:
- You can download a zip archive containing all the pictures shown above in high-res from this [url]link[/url].
- you can view datasheets for the bargraphs here and here and here and here.
- SMT soldering guide at Curious Inventor.
- ATmega64 datasheet.
