BC246T: CTCSS/DCS tones not decoding / Trunking not working

[andy404ns]

Have an interesting issue with an old BC246T. The scanner does not seem to be able to decode any subaudible tones and will therefore not open squelch on transmissions when such tones are set. I've done a bunch of troubleshooting and confirmed it multiple times. I have several of these scanners that have identical programming so I've ruled out any programming errors. Here's an example of what's happening:

Local fire dispatch frequency is 154.1900 with CTCSS 136.5

Results of the scanner with various programmings:

1 - Using CTCSS 136.5 --> Never opens squelch, no audio at all
2 - CTCSS set to OFF --> Squelch opens fine on all transmissions
3 - CTCSS set to SEARCH --> Squelch opens fine on all transmissions but no CTCSS code is displayed

This is across all frequencies programmed into the scanner.

And something that I figure is related: The scanner cannot trunk track. The MA State Police operate an analog Motorola Type II trunked system. The scanner will never hear any transmissions on this system. And again I have an identical set up right next to it receiving transmissions just fine. If I program the voice channels of this system as conventional channels (without CTCSS/DCS tones obviously), then it gets all the transmissions without issue. Seems to be the same kind of problem where the scanner is unable to decode information.

Anyone heard of this kind of problem before?

Thanks!

 

[pb_lonny]

It sounds like it has a fault, if another radio which is programmed the same is working fine. The CTCSS not being found is a sign of this.

 

[Ubbe]

Subtones are read by the CPU, so either the firmware have a problem or the low pass filter that only feed below 300Hz audio to the CPU have a component failure. Try a reset first that will clear all memories so you will have to reprogram it, preferable if you have a software program to use but a lot of programming to do by hand. Hold in button 2-9-Hold while powering on.

/Ubbe

 

[andy404ns]

Thanks guys.

@Ubbe - I've done three factory resets over the last few days with no luck. The firmware is up to date with the latest per Uniden's website but this scanner is quite old. I'll see if I can flash it later today.

 

[tvengr]

The firmware is up to date with the latest per Uniden's website but this scanner is quite old. I'll see if I can flash it later today.

Do you have firmware version 2.60? If you do, I would reload the firmware again. Problems such as yours can be caused by corrupted firmware. If that does not solve the issue, the scanner probably needs to be repaired. Some sites of the MA State Police system require a custom 800 MHz rebanded band plan. It appears that some MSP troops are now on the CoMIRS P25 system. Also, reprogram the scanner if you have not already done so. Are you using programming software?

 

[andy404ns]

Well, the firmware was already at 2.6 but I flashed it to 2.6 again and still having the same issue.

I'm happy to open this thing up and take a look around but I have zero idea what I'd be looking for. Is there a specific component on the circuit boards that would be responsible for subaudible tone decoding?

 

[tvengr]

Take a look at the circuit board. Do you see any corrosion? If so, the leakage paths between foils can cause all kinds of problems. If you see corrosion, a little cleaning with alcohol is in order. Take a close look for bad solder connections and cracks in the circuit board or foils. Bad solder connections on circuit boards tend to show up after about 10 or 15 years.

 

[andy404ns]

Opened it up. The boards look brand new so I don't think there's anything for me to do there. Gonna just remove all the tones and let it bring in everything.