Here is a step-by-step construction of the board for the ICs and components. Feel free to alter it as long as you follow the schematics. Verify all connections as soon as you solder something new, and ensure you have no short-circuits, this will avoid lots of debugging later on.
The first step is to secure the ICs. Lot of room is needed so they shall not be too close from one another. To avoid burning the ICs, solder the IC sockets, but don't place the chips in yet.
Then we secure the LEDs. Instead of soldering the LEDs directly on the board, you can solder pins that will be used in conjuncture with a flat cable to place the LEDs on a further area on your bezel. If you're to do so, I suggest you place a pin header >while soldering< (like an IDE
cable or something) to ensure that the pins don't get bent out of shape.
No matter what you do with the LEDs, remember the cathode (-) is to the LM3914 while the anode (+) is to the 5V.
Then we place the resistors on. Resistors are not polarised, so any direction is fine. The 3K3 ohms from pin 4 to pin 8 of the LM3914, the 10K Ohms from the pin 8 to the pins 6&7. The 330 Ohms is for the RC filter, while the 470 Ohm to the 4N25 transistor entry.
On top of the 330 Ohm, we place the capacitor. Capacitors are polarised, make sure you place its cathode (-) to the ground. The cathode, or negative part, is usually marked by a black line and/or a (-) sign. Also, on pins 1&2 of the 4N25 there is the HDD led header wires, and we need a place to the power entry (Molex connection).
Since we might want to have an option on the mode (pin 9 of LM3914), there is the optional jumper switch you can place on the board. The pin 9 (mode) set to 5V will make the meter act as a bar graph, while if not connected will leave only the highest led ON and the others OFF, a little like a digital needle indicator.
Here starts the wiring. First the GND signal that connects to Pins 2&4 of the LM3914, and the filter (capacitor's (-) and resistor).
