InstructionsBefore you startYou can print out an image of the circuit board silkscreen layer (PNG format | PDF format), to use as a guide for installing components.While you look at the board layout, please also take the time to look at the schematic diagram and associate each part with their location in the circuit. While this is not normally required to build a working amplifier, one of the opportunities of DIY is to learn about how the circuit works. Try to determine what each part does and why the particular part or value is chosen. There are many web resources to help you with this, including the CK²III amplifier thread in the headwize.com DIY workshop forum. You will find the overall DIY experience more rewarding as a result. Circuit board assembly instructionsThe negative voltage regulator's metal tab is connected internally to its input pin. If your heatsink will be in close proximity to the top metal cover when the board is installed in your chassis case, then you should mount the regulators to the heatsinks using TO-220 insulating kits. Otherwise, you may mount them directly to the heatsinks using #4-40 or M3 machine screws and hex nuts, after applying some heatsink thermal paste to the mating surfaces. Set the regulator/heatsink assembly aside for now.Solder the components to the board, starting with the lowest profile parts. This means the resistors, opamp sockets, and small diodes. Then solder the small capacitors, small transistors, Molex headers, trimpots, followed by the output transistors and large capacitors. Lastly, install the voltage regulator/heatsink assemblies, and secure the heatsinks to the board by applying a small amount of solder on their pins. You do not need to heatsink the output transistor if they are biased to flow about 30mA quiescent current and the enclosure is well ventilated. However, adding heatsinks to the output transistors will make bias adjustment easier. If your enclosure has poor ventilation or you plan to set the bias higher than 30mA, then heatsinks become mandatory. Since the CK²III circuit board holes are plated through, you only need to solder the parts from the bottom of the board. Do not drill or enlarge the holes because that would damage the through-plating. Make sure the correct part goes into each position on the circuit board. Measure each resistor with your multimeter to ensure it's the proper value. Pay attention to the polarity of electrolytic capacitors, diodes, transistors, the opamp socket as well as the orientation of the trimpots. Install the DC servo opamp into its socket, making sure it goes in the right way. Clean up the solder flux residue from the board with isopropyl alcohol (or electronics flux remover) and a brush. Install the output transistor heatsinks as necessary. Inspect all solder connections carefully, using a magnifying glass, to make sure there are no solder bridges or cold solder joints. Use a multimeter in ohms scale to check for short circuits. Correct any mistakes before proceeding to the next phase. Next, proceed to the Wiring & ground section for details about wiring up the connections to the board. Main: CK²III Main | Prev: Parts list | Next: Wiring & ground |
