BC95XLT: Uniden BC95XLT Lost Sensitivity (Reception)

[kolbep]

Hi All.
Long time ago I purchased a 2nd Hand Nascar Branded Uniden BC95XLT.
It worked well, and the Close Call feature came in really handy.

But some time ago (i believe it may have been after a drop), it became a lot less sensitive.
Close Call only detects a transmitter right next to it. Standard reception picks up almost nothing,
I have another Uniden Bearcat, and it is right next to this one, and pick up signals nice and strong (has the same freqs in it).

I have reflowed quite a lot of the joints in the RF antenna section, as well as testing continuity from the Antenna connector to the board, and all is fine there.
I have also replaced the antenna with one from a 3rd Uniden radio, and it is still the same.

I did send an email to Uniden long time ago, for advise, a diagram or Service manual. However their only recourse was for me to send it in for repair, which would work out to 2 or 3 times the cost I bought the radio for.

Does anybody have any suggestions as to where I can look to try locate the problem, as I would really like to get this one going again.

Thanks

 

[donc13]

That's the first place I would have looked, the antenna. So next up would be the RF stage and IF stage. Which means the circuit board.

Look carefully for visible cracks or loose connections.

I forget if that scanner receives NOAA weather radio. If it does, set it to receive the local station and while checking for output try pulling or pushing on antenna the front and back and so forth to see if you suddenly get reception. Obviously, use your other scanner to make sure to have a good signal where you are trying to get the NASCAR radio to work.

 

[wtp]

and stop transmitting next to anything !

 

[JoeBearcat]

I did send an email to Uniden long time ago, for advise, a diagram or Service manual. However their only recourse was for me to send it in for repair, which would work out to 2 or 3 times the cost I bought the radio for.

At this point save yourself time and just replace the unit with another if the cost is only 1/3 to 1/2 the repair cost. Then use the one you have for spare parts.

 

[kolbep]

Took another look inside the unit (havent done so in a long time).
There is now signs of corrosion in the RF Section, with several diodes having desintigrated, and taken the pads with them. JoeBearcat is right, I will just have to keep an eye out on my local forums to try get a good deal on another secondhand unit.

 

[GROL]

Since it was dropped, and you have checked the antenna connector, it may still have a loose solder connection with a surface mount component. There is very little solder at all with surface mount. I have repaired a few radios with loose surface mount components. As far as transmitting next to it, it would take a really high amount of power very near the radio to damage the front end transistor or IC, and for an extended period. Usually much older components are more sensitive, but most made in the past several years have good over voltage protection. But, one possibility may be a near strike from lightening. I lost the front end transistor in a radio once due to that. But that radio was connected to a mobile antenna and the lightening was maybe a quarter mile in front of me while driving. A very large bolt that looked like it hit right next to the road ahead. A couple hours later I realized I wasn't receiving anything. I had to replace the first RF amplifier transistor. It had the same symptoms. Very weak sensitivity but it would receive an injected signal or a strong signal very nearby. Considering the age of that scanner, I would definitely not spend any real money on it, but I would probably tinker with it a bit to see if I could trace the signal. Rather hard to do without a schematic and multi layer circuit boards. You could sell it for parts on eBay. You may be surprised. I bought an As-IS Pentax camera a couple years ago for $30 just to get 2 parts off of it that were no longer available. Sometimes it's the only way to get parts.

I was typing this while you posted the corrosion issue. Maybe water got inside? Since it does not work you can try something I would never try on a working unit. I have managed to bring back some electronics by brushing the circuit card under running water with a tooth brush. It removed some corrosion that shorted out adjacent parts. But it usually doesn't work. Once I was on a remote service call and did not get good information from the help line. The issue was a bad keyboard in a chemistry analyzer. I found someone spilled a cola into it. Gooey sugar. I did not have a keyboard, so I wash it in water and then rinsed with alcohol to lift the water. It worked! There was some corrosion already starting from the cola residue.