Uniden UBC785XLT

[geowhitt]

Hi all i need some help as i think i have given my scanner some rf as the receive has dropped.
I am looking for any info or a service manual please pm me.
Thanks

 

[Ubbe]

The difference to UBC780XLT are the removal of trunked mode and 500 additional channel memories. So it should be the same in the RF department.

There are two protection diodes, D1 and D2, at the testpoint 1. Check those.

/Ubbe

 

[geowhitt]

The difference to UBC780XLT are the removal of trunked mode and 500 additional channel memories. So it should be the same in the RF department.

There are two protection diodes, D1 and D2, at the testpoint 1. Check those.

/Ubbe

Hi Ubbe, thanks for the info are they just a diodes as i have some switching diodes.

 

[Ubbe]

I haven't looked at them but in other scanners they are sometimes of the 1 watt type, bigger than normal but are standard silicon ones and are the type that have two diodes in the same encapsuling with three legs. Just unsolder it and see if the scanner performs normally. If the scanner where powered on when it was exposed to RF the circuits after the bandpass filters can also be damaged, and even the switch diodes for the different bandpass filters can have gone bad.

In Hi-VHF band there are varicap diodes that track the filter to the frequency that could be a problem if sensitivity have gone down in only that band.

/Ubbe