The DC Jack is the connector for your external power adapter.
There are three holes for the DC Jack, so place it in the holes and turn the circuit board over. It may be necessary to tape it to the board to make sure it remains in place when you turn the board over to solder.
Be sure that the solder joint is full and strong. You will be pushing the adapter in and out of here, so it is important for it to be sturdy.
Step #3: Distinguishing Between the Yellow Components
There are three ceramic capacitors, marked with a 104.
There is a 100V capacitor that has a 2.5mm spacing with kinked leads. This must be distinguished from the fuse, which has wider spacing, at 5mm, and a larger yellow head.
Refer to the image to make sure you know which component is which. The component on the far left is the fuse. The component in the middle is one of three 0.1uF electrolytic capacitors, and the one on the right is a 100V capacitor.
Plug in the board, but do not touch the right-hand side of the PCB.
Place your multimeter on the 60VDC measuring scale.
Touch the black test lead of the multimeter to the large tab of the 7805 regulator. Touch the red lead to the striped end of the diode. You should measure around 60VDC. It is allowed to be between 40-70VDC.
If your measured voltage is 75VDC, then check your power supply in the wall. You may need to use a power supply with a lower voltage rating.
Do not continue if your measured voltage is above 75VDC.
Now straighten the wires with pliers, and slide the PCB within a couple of millimeters of the tube.
This process is difficult, and you must take care in working with the wires. Gently pull the bent wires, and carefully slide the PCB down to the base of the tube.
If you find it too difficult you may find that cutting the wires at an angle (i.e. cutting the wires so that the profile looks like "/") makes things easier. That way you can fit one wire in at a time.
Before you solder the wires, plug the assembly into the main PCB and make any adjustments necessary to make the tube fit straight and secure. When the enclosure is finished, you will be able to make the tube straight at that point as well.
In locations SW1, S1, S2, and S3, insert the switches. The push-button switches are all the same, so it does not matter which one goes where. However, make sure that the slide switch is inserted into SW1.
Make sure that they are all flush with the PCB before you solder them in and move on.