inside a scanner

[slidder]

after opening up my scanner to tap the discriminator i am curious to know what the 2 black screw type looking inside a silver square box is.. there is what apears to be glue keeping them at the right place ....
also i noticed 4 smaller lil cirlces (silver in colour) that can be turned bearing RT2 RT3 RT5 AND RT6 on the PCB just wondering what they do?

thanks

 

[CraneGuru]

Don't turn them !

slidder,

after opening up my scanner to tap the discriminator i am curious to know what the 2 black screw type looking inside a silver square box is.. there is what apears to be glue keeping them at the right place ....

These are most likely variable inductors, and the black screws are ferrite cores, which when adjusted change the inductance of the circuit. Without the proper test equipment and service info, you don't want to be turning those screws.

also i noticed 4 smaller lil cirlces (silver in colour) that can be turned bearing RT2 RT3 RT5 AND RT6 on the PCB just wondering what they do?

These would probably be variable resistors. Again, no need to turn them, unless you want to turn your scanner into a paperweight.

 

[Zack08]

The variable inductors are probably used to tune the I.F. circuits, and as CraneGuru said, you will do more harm than good if you change them (unless you have a good signal generator and metering equipment )

 

[w0fg]

Awwww, I wuz' gonna tell him that they glued those things to keep people from picking up the encrypted transmission, but that if he's just break the seal and tighten 'em all the way down, he'd be able to pick up everything.

Back in the day, we used to tell annoying CB'ers that to peak their radios they needed to tighten all those down because they usually worked loose in shipping. ...That and that they needed to wrap all their crystals with black electrical tape to prevent crystal leakage.