Cobra 29 LTD Classic problem

[Raccoon]

I've got a Cobra 29 LTD Classic that works and preforms great , as a base radio . But if you put it in the mobile , it works until it gets jolted somehow (bumps and so on) . I figured it most have a loose wire or a cold solder joint somewhere , so I went all through the radio with a magnified lens and flash light .

I found nothing , so I thought I'd ask here and see if anyone might have any other ideas for what might be causing this problem . Any help would be appreciated .

Thanks

 

[Robb]

Sounds like it had one too many car rides already.
I would go over the bottom of the board with a soldering iron and re-heat as many joints that look marginally questionable. That, and use it as a base only.
Maybe you want to buy something for the mobile and keep the 29 at home?

 

[Raccoon]

Hi Rob ...

To be honest , I was already thinking of something along that line , but not along the line of using the Cobra as a base radio . I have a decent base radio already , it's a mobile ... but nicer than the Cobra . I was either going to repair the Cobra ... or ... buy a secondary mobile equally as nice as my base , or buy a nice Base Radio and put my current base in the mobile in place of the Cobra .

if the Cobra is not repairable ... I'm afraid it will go into Garbage.

 

[Robb]

I wouldn't just throw it away - I would just solder a number of questionable joints on the board. If that doesn't work out - then you can sell it 'as is' here on this site. I'm sure many would take it off of your hands and give it a shot themselves.

I have gotten radios from others that didn't work and fixed them. Part of this hobby is discovering the electronics side. What you've described isn't an easy fix; but one that takes some patience and time. The Cobra 29GTL is a genuine talker - I've got one that I've kept for the last ~25 years. It is still ticking - although I don't use it much. Nice radio!

 

[loosecannon]

raccoon,

my guess is that one of the components that is bolted to the chassis has a solder joint that has wiggled loose, or that the power connector is not making good contact. try wiggling that around while the radio is on.

how easy does the power cord fit into the connector on the back of the radio.
it could be that your power cords female receptacles are too wide for the male pins in the power connector of the radio.
you can try tightening the receptacles by prying gently with a jewelers screwdriver.
also check the other end of the power cord for loose connections to the vehicle electrical system.

when a mobile radio is put into its mounting bracket and tightened down, it tries to pull the sides of the chassis apart.
this puts stress on the solder connections of the components bolted to the chassis. new radios come with little rubber washers to put in between the bracket and the radio to prevent this from happening. they tend to get lost.


with the covers off the radio, and the radio on, try bending the sides of the chassis out a bit and see if that causes problems.

you can lightly press on the PC board with a pencil eraser or some other non conductive tool and see if that causes it.

re-heat all the solder connections of the components that are bolted to the chassis.

good luck with it,
LC