I have an old Sapphire XIX AM/FM radio. The AF amplifier and the FM circuits work. The on/off switch is bad, and I would like to bring the AM back to life
"Switching it over to AM, searching for a truer sound. Can't recall the call letters, steel guitar and settle down".

I don't have much in terms of a signal generator, nor do I really know how to use one - I guess I can learn. What are the chances I can fix the thing by replacing the electrolytic caps? Also, how hard is it to do. I can solder pretty good but don't mess much with surface mounts cause my hands aren't steady enough.

Is it the switch that s bad? Or something on the board?

Desolder and resoldering in a new switch would not be complicated task. Just get some solder wick or a solder sucker and you would be good to go.

If you can locate the bad component fixing it isn't complicated. Maybe a decent multimeter to check continuity between the switch and the various components.

Also, there is often a fuse. Are you sure that the fuse didn't blow at some point, making it seem like a faulty power switch?

Zach

Old radios are unlikely to have surface mount components... If you can read the sizes and such, it's worth a shot to just replace them. I'd be surprised if equivalent modern caps were expensive.

--DD

Oh, I am sure there are no surface mounted components. Just said that to give a hint at my level of dexterity with the solder.
Thanks.

I identified the switch problem right off. The light comes on when I start to turn the switch, then goes off.
If I bypass the switch by jumping 12 v to the bulb holder I get nice FM mono. But no AM. I have the schematics, and that is how I figured out where to add 12 v. The switch is ganged to the volume control pot.
I was wondering if anyone on the board does radio repair, and could provide advice.

I can afford to have the radio sent out for repair, but like other aspects of 914, such as machining and engine building, welding, painting and fabrication I like learning how to do things. Under those circumstances it is a miracle that I have two 914s on their own wheels. Maybe I should buy a radio repair guide from 1975.

Don't send it out yet.
Order a can of Deoxit D5 contact cleaner (try Amazon) and spray the offending switch. Follow the can's directions and work it in by pushing the switch several times. Let dry and try. I've come to rely on this stuff being an old stereo collector.

How did you determine the caps need replacing? You are braver than I as I would not try repairing a radio with limited equipment and knowledge. I think there might be some tuning necessary if you change the caps.

Be careful removing the caps as applying heat to an old PCB might loosen the traces and pads. I would not use a handheld solder sucker to open up the through holes because they could damage the traces. Maybe use desoldering braid to remove the solder.

Good luck.

the capacitors are the most likely to fail and the new style ones actually provide better sound. They solder in so if you are handy with a soldering iron, more power to you to replace them.

I remember years ago I used to get Heathkit items from my parents for Christmas. Once I bought a Vox jaguar organ in a million pieces, and had to solder a circuit board for every note.... took me months. Must have soldered over a thousand joints! THEN when I was finished, not all of the notes worked so had to send it to Heath Kit for them to repair! What are the chances that one could successfully solder over a thousand joints without one being bad!!!

If it's the caps, a visual inspection would show them swelled and/or leaking.

Are the caps shorted? Desolder half of one & test for zero resistance. If they're not shorted, then I wouldn't bother replacing them.