Uniden BC780XLT vs. Radio Shack Pro 2038 volume level

[rhrailfan1972]

Why is it that my Pro 2038 is louder at half volume than my BC780XLT is at full volume? Could it be a issue with the Uniden? And no I do not need hearing aids haha.

 

[rf_patriot200]

Why is it that my Pro 2038 is louder at half volume than my BC780XLT is at full volume? Could it be a issue with the Uniden? And no I do not need hearing aids haha.

There is a rarely known mod for the 780xlt that should fix this, unless there's another problem with it. Set All of your VHF frequencies to NFM in the menu, and you'll notice they'll be louder. There is a circuit which compensates for NFM signals.

 

[rhrailfan1972]

I figured out earlier they were all set to normal FM so switched two of so far to NFM. Made no difference.

 

[rf_patriot200]

I figured out earlier they were all set to normal FM so switched two of so far to NFM. Made no difference.

Ok, you might have a problem with the audio amp in your 780 then. Are the Weather channels normal volume or not? I never have to turn my volume more the 10; oclock to hear it all over the room.

 

[rhrailfan1972]

Weather channels are the same

 

[rf_patriot200]

Weather channels are the same

Low volume, or Normal ?? IF your WX channels are good and loud, then obviously that would rule out a weak audio amp.

 

[rhrailfan1972]

WX channels are also louder on the Radio Shack compared to the Uniden

 

[rf_patriot200]

Here's another trick, try inserting a External speaker in the jack in the Rear and pull it in/out a few times and see if that makes a difference ?

 

[rhrailfan1972]

Ok I shall give that a try later today when I return home

 

[rf_patriot200]

Ok I shall give that a try later today when I return home

Hopefully it helps, I use a Motorola speaker plugged into mine, and it get insanely loud.

 

[tvengr]

WX channels are also louder on the Radio Shack compared to the Uniden

Old scanner and low volume = bad electrolytic capacitors in audio amp.

 

[rhrailfan1972]

Kind of what I was thinking but was not sure

 

[pro92b]

The BC780XLT and PRO-2038 were both made by Uniden. The PRO-2038 is actually about four years older than the BC780XLT which was released in 2000.

If exercising the external speaker jack does not restore the volume then it is time to replace capacitors connected to the audio amplifier IC labeled IC5. The attached schematic shows three capacitors to replace. C75 was originally 100uF but if you find the audio to be tinny then upping it to 220uF would be ok.

 

[rhrailfan1972]

Thank you for that info!

 

[pro92b]

There is a further issue with the BC780XLT audio. Does the audio maximum volume improve when an external speaker is plugged in compared to the internal speaker?

 

[rhrailfan1972]

It does not

 

[pro92b]

That suggests that the capacitors do need to be replaced. Try the external speaker volume test again after the capacitors are replaced.

 

[tvengr]

I see the BC780XLT uses the same TDA1905 audio output IC as the Radio Shack PRO-197. It is replaceable by a NTE7000. The electrolytics are most likely the problem. Decreased capacitance will often result in loss of low frequency response in the audio.

 

[Ubbe]

Some times when there's a problem with scanners it is its power supply that are bad and can't deliver enough power.
Try any other DC 10-15V power supply you have that have a similar type of plug with positive at the center. Power supplies and its capacitors age much faster than a scanner due to the excessive heat.

/Ubbe

 

[kruser]

I see the BC780XLT uses the same TDA1905 audio output IC as the Radio Shack PRO-197. It is replaceable by a NTE7000. The electrolytics are most likely the problem. Decreased capacitance will often result in loss of low frequency response in the audio.

I wonder how long NTE stuff will be around. NTE closed up shop earlier this year.
I have one NTE7000 left and one ST version of the TDA1905.