SUPERSTAR 3900 Clarifier Modification
Original © 1994
Above we have shown the original SUPERSTAR 3900 clarifier circuit as it comes from the factory. Notice that this unit uses two crystals controlled by the HI/LO switch in combination with the LO/MED/HI switch (ABC on some models ). Changing either one of these crystals to different values will also provide a whole new range of channels if so desired.
Most radios use only one crystal in the PLL circuit thus eliminating this dual crystal circuitry. Although this circuit functions well, it sometimes tends to have drifting problems, as many of you know. On the following page we have shown the standard clarifier slide modification for tracking RX and TX. But if you really want to go a long way towards eliminating much of your drifting problems do the 20K-10 turn pot modification.
1. First unsolder the green wire from point 54 on the circuit board and resolder to point 14 ( 8.7V Supply) as shown in Fig. SS3900Mabove. Next unsolder the yellow wire from the clarifier control and seal the yellow wire end with a piece of heat shrinkable tubing. You will not use the yellow wire with this modification
2. Next Locate D75 and R135 (33K resistor) and cut one end as shown above. Your clarifier will now track RX and TX.
SUPERSTAR 3900 Clarifier Modification W/10 Turn Pot
1. First unsolder the green wire and the yellow wire from the original clarifier control, and seal the ends of each of these wires with heat shrinkahle tubing. You will not use these wires on the new pot. Next unsolder the brown wire from the clarifier control and leave hang loose. Next unsolder the White, Violet, and Blue wires from the clarifier control and leave them hang loose also. Now remove the original clarifier control and install your new 20K-10 turn pot.
2. Now solder the White, Violet, and Blue wires to the new clarifier pot as shown in Fig. SS3900 to the right. Next resolder the loose end of the brown wire to point 14 (8.7V Supply) as shown in the diagram above. Next Locate D75 and R135 (33K resistor) and cut one end as shown above. That's it. Note: Sometimes it may be necessary to reconnect R135 if clariGer is unstable. That's why you should never remove anything completely bom the circuit. Only cut one end as shown. Then it will be m ucb easier to reinstall or resolder a component to the circuit board.