BCT15X: Wanted

[Codar]

Sorry, I got the name wrong George.... I'll clarify, it's Georges scanner I'm trying to repair.

Dave

 

[Ubbe]

..... and I will need to find where the squelch control comes out, I have a feeling it's done within the CPU

Correct. It's writing the SQ values on the display so the sq pot position are read in the cpu and then the cpu should have an output that regulates the sq circuits analog part that then detects when the sq open and close. The schematics are at www.mods.dk

/Ubbe

 

[Codar]

The variable voltage from the pot IS reaching the cpu so IC 32 op-amp is doing it job, the squelch numbers alter anyway theres a clue.

I'd be thinking something has gone wrong within the CPU.... I can only think of trying a fresh firmware update, other than the squelch being wideopen it still receives.

Dave

 

[Ubbe]

The schematics indicates that there should be a testpoint labeled NOISE. It starts at a high DC voltage and the more signal strenght that are applied the less the voltage should be, and be down to almost 0 with a fully saturated signal. If that doesn't work then the problem are between that point and the radio discriminator. Probably not enough audio signal to the squelch circuits if the voltage only goes up to 2volt or something as max.

If that NOISE voltage seems to move between its min and max values then it has to be a CPU problem as the signal goes directly thru a rresistor to the CPU, that then controls the audio mute and scanning. Did you try to read the programming from a PC, to be able to restore it afterwards, and then do a reset, 2-9-HOLD while powering on?

/Ubbe

 

[Codar]

Thank you very much Ubbe, yes the noise is there and varying. I haven't tried reprogramming or reading as yet as yet.... I did try the 2-9 hold, I'll try it again to be sure.

Dave.

 

[iMONITOR]

Thank you very much Ubbe, yes the noise is there and varying. I haven't tried reprogramming or reading as yet as yet.... I did try the 2-9 hold, I'll try it again to be sure.

Dave.

You're turning the scanner OFF, and then pressing all three with the scanner OFF when you do that, and still holding all three down while you turn the scanner back ON, correct? Are you seeing the message on the screen that the scanner is being reset and will lose settings and programming, correct?