BC860XLT Open Squelch issue.

[dgruber]

Hi every one so I have a BC860XLT and the squelch seems to be open all the time and I cant get it to close the Squelch. I have the squelch nob turned all the way down but I still get noise. This happens on all bands.




Thanks!
Dgruber

 

[parnass]

Hi every one so I have a BC860XLT and the squelch seems to be open all the time and I cant get it to close the Squelch. I have the squelch nob turned all the way down but I still get noise. This happens on all bands.




Thanks!
Dgruber

I don't think I have a schematic for the BC860XLT. This excerpt from an article I wrote long ago may give you some clues as to the cause:

REPAIR TIPS: BEARCAT SCANNER RADIOS


" ... Most Uniden/Bearcat base/mobile scanners feature an AUTO
squelch position, actuated by rotating the squelch knob
fully counter clockwise. The BC350 used a separate
pushbutton switch for this purpose. These scanners use a
flimsy potentiometer (designated R81 in BC300s) internally
mounted on the RF circuit board, to set the level of signal
required to open the squelch when in the AUTO position.
This pot also has an effect on the squelch action in the
non-AUTO mode, and determines at which point the squelch
knob must be positioned in order to silence the radio.

Although the potentiometer is adjusted at the factory,
changes in component values due to aging often necessitate
readjustment of this internal pot. Misadjustment of this
pot has been the cause of "no squelch" complaints in two
BC300s and a BC250 I fixed.

Another squelch failure is due to a blown transistor that
acts as the electronic switch in the squelch circuit. I
replaced this transistor in only one BC300, so I don't know
if this is a common problem. ..."

 

[ziesenis]

I don't think I have a schematic for the BC860XLT. This excerpt from an article I wrote long ago may give you some clues as to the cause:

REPAIR TIPS: BEARCAT SCANNER RADIOS


" ... Most Uniden/Bearcat base/mobile scanners feature an AUTO
squelch position, actuated by rotating the squelch knob
fully counter clockwise. The BC350 used a separate
pushbutton switch for this purpose. These scanners use a
flimsy potentiometer (designated R81 in BC300s) internally
mounted on the RF circuit board, to set the level of signal
required to open the squelch when in the AUTO position.
This pot also has an effect on the squelch action in the
non-AUTO mode, and determines at which point the squelch
knob must be positioned in order to silence the radio.

Although the potentiometer is adjusted at the factory,
changes in component values due to aging often necessitate
readjustment of this internal pot. Misadjustment of this
pot has been the cause of "no squelch" complaints in two
BC300s and a BC250 I fixed.

Another squelch failure is due to a blown transistor that
acts as the electronic switch in the squelch circuit. I
replaced this transistor in only one BC300, so I don't know
if this is a common problem. ..."

How would one go about replacing that pot if it broke? I have been unable to find out what rating it is or one similar to it. Any ideas? It has F271 4107 on the side and it's in position L12 on the PCB. It has 7 leads on the PCB but 5 go to ground. The pot also has 7 leads, with only 3 leads being used on the pot itself. The rest are to hold it in place I suppose.