Cobra
Service Bulletins
Documentation Project
CBTricks.com
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Bulletin
#
|
Service Bulletin Description |
Models
|
The local NOAA weather station is not received. | 18RV, 23 Plus, 41 Plus | |
All channels are locked on the same transmit frequency. (R130 burning on 148-series) | 148GTLST, 148NWST | |
Tx squeal on 25-series w/SoundTracker engaged | 25 Series Radios | |
Squealing & muffled sound on HG mikes | HGM73, HGM75, HGM77, HGM84, HGM84W | |
Cobra
has switched to a different type of potentiometer for the volume and RF Gain controls. The old potentiometer is round, the new one is square. The potentiometer mounts on a small PC board. The new potentiometers will not fit on the older PC boards. |
All 148s with front-mount microphone. | |
Meter
needle sticks after transmit, and there is no receive. Pushing the Soundtracker button (if equipped) may restore proper operation. |
All versions of the 29LTD | |
We have
switched to a different PLL chip (IC1). The older chip is the 2816, and the new chip now says 29LTD on it. |
All versions
of the 29LTD, including models with weather, Soundtracker, and Nightwatch. |
|
Disable Soundtracker | 25, 29, and 148 with soundtracker | |
Warble
when transmitting on sideband. This can occur if the power supply cannot keep up with the power demands of the transmitter. |
148 GTL, 148 GTL ST, 148 NW ST | |
No transmit power on AM. | 148 NW ST | |
Excessive PA feedback | 19DXIII | |
Squealing on transmit. | 148GTL, 148NWST | |
This document provides a list of part numbers for the LED channel display. | 18, 19, 21, 25, 29, 148 | |
Intermittent
transmit, intermittent receive, intermittent modulation, squealing on transmit or receive, or other erratic behavior. |
All CB models | |
You can still hear sound from the speaker even when the volume control is turned all the way down. | 25 WX NW ST | |
Squealing on receive when using an external speaker. | 25 LTD ST | |
Replacing the NB8719 PLL chip with an MMB8719. | 148 | |
Replacing the Nightwatch power supply module. | All Nightwatch CB models | |
Excessive alternator whine. | All 25s with front microphone connector | |
How to add talkback. | 200 GTL DX | |
Receiver
overloads when receiving a strong signal, resulting in distorted audio. In addition there may be a warble in the modulation when transmitting (which might be described as a popping sound during transmit). |
150GTL, 200GTL | |
Reduced adjacent channel rejection when the Noise Blanker is on. | 200GTL | |
Speed-up the echo effect (add reverb). | 150GTL, 200GTL | |
After
adjusting the squelch control, sometimes received signals may sound choppy due to the squelch repeatedly opening and closing. |
150GTL, 200GTL | |
The HF50-12F(Q35 and Q40) finals are no longer available. | 200GTL | |
The frequency display is not accurate. |
200GTL
DX
|
|
Modulation may be low with some noise canceling microphones. | 200GTL | |
When transmitting, there is sometimes a pop in the modulation. | 150 GTL DX | |
Motor boat noise in RX audio. | 25 NW LTD | |
Excessive acoustic feedback when transmitting with talkback. | 29 LTD SE | |
Adding talkback | CB models 25 and 29 (all versions) | |
The ANT light is coming on even though the SWR is below 3. | CB model 29 (all versions with the ANT light) | |
How to increase the volume of the talk-back. | CB model 29 (all versions with talk-back) | |
How to adjust the talk-back volume. | 200 GTL DX with factory talk-back | |
How to adjust the BRT / DIM lamp intensity. | 29 LTD with factory blue lighting | |
How to increase the talk-back volume. | 150 GTL DX | |
Audio amplifier versions on the 25/29 | 25/29 Versions | |
2SC1969 substitute for the 148GTL | 148GTL | |
No Display on the 29 LX LE | 29 LX LE |
Disclaimer: Although the greatest care has been taken while compiling these documents,
we cannot guarantee that the instructions will work on every radio presented.