1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

uniden washington 8719 channle mod question

Discussion in 'CB Radio Modifications' started by dss56, Jul 6, 2018.

  1. dss56

    dss56 Active Member

    Sep 27, 2010
    Likes Received:
    I have a washington where I think I add pin 9 to 14 8volts without isolating the pin 14. Now the channel 37 38 39 40 is 41 42 43 44 and will not go back to regular 37 thru 40. all other channels work. Did i pop the 8719 chip? I did change xtal to 11.3258. I totally forgot to isolate pin 14 with the 4.7k resistor.

  2. nomadradio

    nomadradio Analog Retentive

    Apr 3, 2005
    Likes Received:

    When you hooked the 8-Volt supply to pin 14, the channel selector would pull the 8 Volts to ground on the channels where that pin is "0". The selector simply switches the chip's pin to ground for a logic zero, and opens the circuit on that pin for a "1", with 8 Volts on that pin.

    Makes it sound as if maybe the contact point for pin 14 could have been damaged inside the channel selector?

    It's not that tough to check. Remove power from the radio. Put your meter's ground clip onto the radio's power-supply ground. Now set the meter to ohms, and touch the red probe tip to the channel-selector side of where you cut the trace to pin 14. Select channel 1. You should show close to zero ohms. Now select channel 2. The reading should rise to a few thousand ohms or more.

    If it does, the channel selector is okay. And if you can't get a continuity reading to ground on channels 2,3,4,8,9,10,11, 15,16,17,21,22,24,25,29 through 32, and 37 through 40, the switch is partly bad inside.


Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!