LesComm

8719-192-L-PLCC Cobra 2000 KIT INSTRUCTIONS

 

 

 

 NOTE: RADIO MUST BE IN ORIGINAL CHANNEL CONFIGURATION. ALL CHANNEL MODS MUST BE REMOVED AND COMPONENTS RETURNED TO ORIGINAL CONDITION.

 

Presteps;

Replace the MB8734 PLL with an MB8719, MMB8719 or a RCI8719-99 PLL.

It is recommended you replace X3 (11.3258) with the enclosed xtal.

Note: Due to a problem in the manufacture of the xtal, the +10kc switch is now a DROP 10kc switch. This is not a bad thing as it now allows coverage down to 26.055.

Connect the WHITE wire from connector J3a to pin 10 of the PLL on the top of the IC.

Connect the RED wire from connector J3a to J29 as shown. This is the best place to pick up a clean 8 volts.

 

 

 

Ranger made Cobra’s, (2010GTL) Refer to figure 1. If your PLL IC is labeled like the one in this pic “RCI 8719-97”. Do not replace the crystal. Instead, leave the original crystal in place and connect A14 to +5 volts.

If your radio has the PLL IC labeled “RCI 8719-99” replace crystal with the 11.0758 xtal.

In both cases, install RA1 common pin to the +5 hole (pull up).

 

 

 

Take note of the connector labels. One pair is for the 959 style chassis (939, 949, 959, 969, 696, FD-1, 699, 2547 etc.).

The other pair is for the 979 style chassis, (919, 929, 979).

 

For the Cobra type radio’s, use the connectors labeled “979”.

The 959 connectors should not be installed on Cobra boards assembled after 8-1-09.

 

CAUTION! Connecting your radio to the wrong set of connectors could permanently damage your radio!!

 

1. Remove bottom and top covers.

 2. Locate the muti colored wires coming from the Channel Selector board and connecting to the main board. They are right the meters.

 3. Unsolder the multi color wires at the main board, that come from the channel selector board, to the main board.

 

Leave the Gray wire.

 

4. Clean out these holes.

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 5. Wire connector 1-J1A to the same color wires as shown.

Plug the loose end into J1a, (labeled 979) on the LesComm board.

 6. Wire connector 2 to the main board as shown. Again, take note of the SILVER MARK. Connect the cable to J3a (labeled 979) on the LesComm board.

 THE SILVER MARK GOES TOWARD THE OUTSIDE

 

 

 

7. Remove R95. Located close to the PLL IC.

 

8. Find a suitable place to Mount the LesComm board, install the band switch and the 10kc switch.

 9. Connect to power and power up the radio. STOP. Check for full coverage. If full coverage is present, you’re done. Replace covers. If not, proceed to step 8.

 10. Place the Band switch in the D (4)  position, channel selector on channel 1.

 11. Using a digital voltmeter, measure the voltage on pin 17 of the 8719 PLL chip. (Should be approximately 4 volts.)

14. Connect the voltmeter to test point 1 (Cathode of D1) on the LesComm board. Refer to Figure 1.

 

15. Adjust VR1 to match the voltage you measured on pin 17 of the PLL, minus .3volts.

Example; If you measured 4.65 volts on pin 17, set VR1 for 4.35 volts at TP 1.

Note: If using an MMB8719, set voltage .6 volts below pin 17.

16. Check for full coverage.

 

17. Switch to channel 40. Select Band A.

 

18. While measuring the voltage on pin 8 of the PLL (approx +8 volts), slowly go down in channels until this voltage becomes unstable and drops off. This is the lowest frequency the radio will cover. With an 11.1125 crystal, usually around 26.325 on the RCI8719-97 PLL radio’s.  26.175 on the RCI8719-99, MMB8719 and MB8719 radio’s.

 

Reassemble your radio and Enjoy!

 

 

 

 

 

 

 

 

If you're still having problems, double-check the following;

Check that A15 is +5 volts. A15 is located close to IC1 and the regulator circuit, on the J1 side.

Ensure that RA1’s common pin is to +5 volt hole (pull up).

RA1’s common pin is denoted by a dot above the pin. 

 

 

Side Notes; Power falls off at the ends of coverage on the Uniden made radio’s more than the Ranger made units. It is possible to balance out the power from the top to the bottom, but that’s not covered here.

The RCI8719-97 is a 7 bit device, but the internals of the IC do not allow it the control of the VCO as well as a -99. If you have the RCI PLL, I recommend you replace it with an RCI8719-99 and change the crystal. You’ll be much happier with the results.

 These instructions should also apply to the President or Uniden Madison.