Hi folks
Some progress at last. This thread prompted me to go back to my Selena 212 which has this FM problem. As I said earlier, I had become convinced that the FM tuner module was faulty, so today I slipped the tuning drive off and piled in.
The Trader service sheet 3330 from 1978 is really not very good. There are no test voltages given, and the audio amp circuit is completely different from the one in my set. I mentioned earlier about the component diagrams being mirror images, which also doesn't help. In tracing the FM tuner circuit, I found there is also a mistake in the circuit diagram, and some of the component values are wrong. For example, R1 in the FM tuner is given as 1 ohm, whereas the component fitted is 1.5k.
Anyway I couldn't find anything wrong with the FM tuner. The voltages all looked plausible, and I couldn't find any components wildly out of spec, and the transistors seemed OK. Somewhat disheartened, I decided to reassemble everything, and put it back on the "pending" pile. At which point I noticed that I hadn't replaced two 5uF electrolytics on the IF board. I slipped in a couple of 4.7s, and away she went!
These were C115 and C117 in the detector region of the circuit. I can't think why I didn't replace them before.
In fact, in the 212 there are only four electrolytics on the IF board (that's the one that faces you when you take the back off the set), so first off, try replacing them all.
The set now has bags of volume on FM, and I am beginning to realise what people see in these radios.
I'd be interested to hear if this works for anyone else.
Cheers.
Tom
