I suggest you start with assembling the LED Matrix 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. You probably noticed that you received 40 pcs of bargraph style LEDs each with 10 LED so you have to use 2 for each column.
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. I suggest you start from the left and place each column, first the top bargraph then the bottom one.
- Anode mark
The LED's will not fit directly and they are going to need some adjustments to get them in(this is because of pin spacing/alignment but it will help us later when we turn the board upside down as it will keep the led's in place). This is my preferred method for making them fit: first place the left side inside the holes than with some thin and hard object(I'm using a PCB) apply a small force on the right side of the pins while keeping pressure with your finger on top of the LED to force it in the hole.
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 but in both cases it should be soldered on the back of the board.
- LED Matrix 50 pin IDC connector for "by cable" version
- LED Matrix 50 pin IDC connector for "back to back" version
After soldering the connector you can move onto the motherboard. Soldering the motherboard with solder paste in a reflow oven is highly recommended. As you may of noticed the parts are shipped 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 solder all the capacitors and resistors with the values indicated in the silkscreen except for C2 which was changed from 100uF electrolytic to ceramic 22uF in 1210 package for improved stability of the dc-dc converter. Next step is to solder the connectors and you have 2 options for the 50 pin IDC connector as illustrated in the next two pictures:
- motherboard 50 pin connector for "by cable" version
- motherboard 50 pin connector for "back to back" version
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 up to the top 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 or adjust the level of the input on the motherboard from the pot marked with "Adjust input". You can ask your questions about assembly in this topic and also your suggestions are welcomed.
