PPM3 Phone Patch Mixer Assembly

Assembly of the PPM3 is easy but still requires some time and patience. We will start with the surface mount parts and get them out of the way.

As with any static sensitive parts be careful when installing the IC’s in this kit. Don’t rub your feet across the carpet and then grab the chip out of your kit as it may be damaged. It’s helpful to ground yourself to a metal object before picking up and installing the next three parts.

1. Install U3, the SSM2165-1S surface mount IC. Be sure you have it lined up with the silkscreen on the PC board so that the notched or dotted end of the component is placed correctly. In the case of U3 the notch points toward C13. The dot or notch indicates pin 1 (the pin beneath the notch if the notch is to the left) and the rest of the pins are counted by going around the chip in a counterclockwise direction. Tin one pad and then line the IC up so that all the other pins are placed over the pads they will be soldered to. Once the chip is lined up correctly, carefully solder the pin to the pad that was tinned. Make sure that the rest of the pins are lined up well before soldering a pin on the opposite side of the chip, then continue around and solder all the pins. Be careful not to bridge the traces between two of the legs of the chip.

2. In the same way, install U1. The notch or dot on this chip is placed toward C30, opposite of U3 that you just installed. Follow the same method and be sure that the pins line up well before soldering them all into place.

Whew! That was some work. But the toughest two parts have been placed. Check over your work to be sure there are no unwanted bridges and that the pins all look soldered. Now let’s move on to the larger through-hole components.

3. Install U2, the LM6484AIN IC. Follow the PC board silkscreen and Parts Layout Diagram for proper orientation of this part. The dot or notch on one end indicates pin 1. The chip must be placed correctly or it will not work. Be sure to solder all 14 pins. We’re soldering this part in first so that you can let the board sit on it to keep the part flush to the PC board. Simply solder in one corner pin, make sure the others are all through the board equally, and then solder the other corner pin. Check flatness again, then you can solder the rest of the pins

4. Install C21, 10uF electrolytic capacitor. Electrolytics are polarized and must be installed correctly or they tend to explode. You’ll see a marking on the PC board to indicate the positive lead. On the part itself you’ll see a band or stripe down one side; this indicates the negative lead. This lead is typically the shorter of the two leads as well. Be sure to orient the part so that the positive lead goes in the hole marked with a ’+’ sign, then solder the part in place.

PPM3 Page 15