Agreed.
I believe this radio, circa 1980, would have bad electrolytics by now.
I sent a Cobra 25 out to Loosecannon and he found at least two that had shorted.
He gave her the full treatment and it's good as new.
I'd like to see if I can pick out on the schematic which cap may be shorted, causing the power draw and no audio.
I don't want to throw parts at it and cross my fingers, even though we all know a recap is needed and would probably fix it.
I'd like to learn something with this one.
It is recommended (and indeed at most times crucial) to remove capacitors from the circuit to test them. You will need a way to test for continuity (digital multimeter), be aware that as electrolytic capacitors begin to fail the ESR value may go off the charts while the fault does not prevent itself as a dead short! (A capacitor can be bad, & not test as a dead short!)
I cannot say that I recommend replacing just a few capacitors as you would likely have problems down the road from the other original caps failling.
Looking at the schematic, from the DC input follow that and look for any filtering capacitors or electrolytics, if you had a DC filter cap that was shorted to ground I assume the fuse would blow immediately.
If you want to learn how to diagnose the radio, I commend you on your journey this path is short by no means.
I would recommend immediately replacing the capacitors and then see how the radio performs, someone once suggested that I learn to discern the DC path from the RF path in the schematic.
When you're testing the radio make sure it has a microphone plugged in, try an external speaker, make sure you have a 1 or 2 amp fuse in line and also attach an antenna to it, some radios will not produce any audio without an antenna/microphone. (You may already know this, but I'm adding it to the thread for good measure.)
I hope this helps.
-LeapFrog
