Hi, everyone:
I got an vintage Sony Digital 24 radio clock, the clock works fine but the AM/FM radio can not received stable signal.
It some time can receive some channel, and then auto disconnected.
Here is the outlook:


I teardown the radio module, and guess the problem is some component getting aged,
I check the connection of circuit is good, but can not recgonize the component to adjust radio frequency is, which have four screw in the corner, and what is the four screw for? trimming the value?

The white square noted as VC (Variable capacitor?)

The question is:
What is the components and what the screw for?
What may cause the unstable radio connection?

Thanks!
Best reguards

 

Hi,
yes, it's a variable capacitor. Don't touch those 4 "screws", actually, those are trimmer capacitors.
First of all, check all electrolytic capacitors . Usually they are dried and their ESR is high.
An ESR checker is very usefull for repair

 

That's a Variable Capacitor, with four preset trimmers for the FM and AM bands, two for each. Don't touch these as they will alter the tuning range , as they are for the local oscillator and tuning.
There may be loose solder joints on the pcb , try to narrow it down by seeing if it is on AM or FM .

 

Post the model number. I may have the service manual for it.

Dan

 

Post the model number. I may have the service manual for it.

Dan

If you have one, it will be very helpful!!
The model num is
SONY ICF-C230