Cobra 2000 took a bump and is now wacky

[Dart]

Hello everyone,

I recently sold my Cobra 2000 on eBay and as luck would have it, it must have taken a few rough bounces during shipment. It was returned by the buyer, so here we are. Here is the problem......

My channel frequencies are duplicated. Channel 18 and 19 are both 27.185. Channel 20 is ok. Channel 21 and 22 are duplicates. This pattern continues throughout the band.

I have verified this with an external frequency counter also.

Any ideas? Thanks in advance.

 

[sp5it]

Cold/broken solder joints. Channel selector and dependencies. Good light, loupe and examine.
Mike

 

[wavrider]

MB8719 PLL chip?
Has any frequency mods been done?
As stated above sounds like the channel selector,,solder joint on ribbon connector
If is still RX and TX just not following the correct channel as displayed on indicator
it is most likely the channel selector got damaged in shipment

 

[nomadradio]

Duplicated channel frequencies pretty well boil down to a a few causes.

A bad circuit on the channel selector. That is, an output to the PLL chip that stays either high or low and won't change when it should.

A broken connection between the selector and one of the input pins on the MB8734 (or 8719) PLL chip.

A bad PLL chip. Typically only happens when someone plays with the wiring between the channel selector and the PLL using a soldering iron with AC leakage-current issues Between a line-operated heater with no ground pin on the cord and the tip. Not likely to happen while packed inside a carton.

A close look with a magnifier and bright light at each wire leading to pins 11 through 16 on the PLL chip, and the other end of each wire on the selector may reveal the cause.

To make channels 18 and 19 come out as the same frequency, this suggests that pin 16 is not changing from high to low every other channel like it should.

73