Vintage SONY Digital Clock Radio ICF-C12W no audio

[CapLeaker]

you can tweek it without equipment pretty well,
you set the dial to the frequency of a known radio station,
then mess with the cans till you get that station with the strongest audio you can.
BUT you must use a plastic tool because a metal screwdriver effects the tuning

that would be a last resort measure…

[Agent24]

Go to your local ham radio club and politely ask for help.

Good idea! Why didn't I think of that?.... haha

[UserXP]

Good idea! Why didn't I think of that?.... haha

I just might do that, it's an excellent piece of advice, never crossed my mind! 🙂
I will post back the outcome.

[UserXP]

Hello, guys. I have been quite busy for the past few weeks, so I didn't have much spare time to work on the radio. I did, however, manage to get in touch with the local radio club and they recommended visiting them as they have several members who deal with older pieces of electronics in the field of radio. But, I didn't have the time to do that as they are open only on two specific days per week after 7 pm, but I definitely intend to visit them as soon as possible.
Now, and idea comes to my mind. If you remember, I replaced the original Tracon capacitors in this unit going with with the same ratings from the single same manufacturer (WE). I now have the idea, since I mended the damaged IF transformer and got promising results, that maybe I should go closer to the original caps. My other working unit has Rubycon CE W series (light blues sleeve) capacitors inside rated at 85°C. Do you know which modern Rubycon series is the closest equivalent of this exact series? I am thinking about ordering them if they are still produced in all the same ratings and go with the Japanese caps altogether. This will also provide me with proper spare caps for my other unit should I need to do any other replacements as well.
Thanks as always for any info on this.

[stj]

those are general purpose caps, i wouldnt bother.

[Agent24]

Rubycon's most basic general purpose series is currently PK, or WA if you want a smaller can size. Both are only 85 degrees rated.
I imagine they would be the closest to the originals, although maybe harder to get since most people want low ESR or higher temperature these days.

I'd be surprised if it made any difference, though, the ones you put in are probably fine. From what I saw you used WCAP-ATG5 series? They are general purpose too, just 105 degrees rated instead.

[UserXP]

Yes, that is true. In the service manual, all the capacitors have the same capacitance as the one printed on the caps -except for 16v33uF which is supposed to be 16v10uF. I first went with those ratings, but I will include a 16v10uF this time as per manual to see if it will make a difference. I've read that using caps with higher capacitance in radio/audio circuits can actually hinderv the frequency reception.

Also, I have a question. When opening T4, I noticed that its internal cap looks like a coil actually, in the shape of a hollow tube. On each side the "wire" is simply straightened and goes to the lead where it's soldered. One of these ends was torn when the T4 suffered the damage in which it lost one of the pins and the ferrite coil contact.
Now, i was thinking, by soldering an extension wire from that capacitor's end to the pin, it may have influenced the total capacitance of this internal capacitor. Would it be possible to measure the capacitance of this cap and possibly replace it by adding an external one soldered between the respective T4 pins?

[UserXP]

Or, unwinding 3-4 turns of the cap's original wire just enough so it can reach the pin for being soldered onto (would this dramatically change that capacitor's performance)?

For the first suggestion, I would surely have to unsolder on end of the cap off the pin to attempt to measure its capacitance, if possible. Could then use an external cap?

[Agent24]

Just the way they've connnected the wire to it, I'd say. I would leave it alone, if you damage it you don't know what the value is.

I think what you need to do is to get it aligned correctly now that you fixed the broken connection.

[stj]

leave the electrolytics alone,
every time you heat those old single sided boards you risk the traces lifting.

[UserXP]

Hi, people.
After a long pause, I would like to kind of update this topic. I took the radio to a local radio club, but they couldn't do it. I then decided to try and align the reception a bit by myself. I first replaced the CF, just to see if it would make a difference. I then made a small plastic tool to use for turning the snugs. I then confirmed that T1, T3 and T4 influence the FM signal, T2 and T5 (both red) affect the AM sound.
The blue T4 increases the volume the most and there is very small range within which it has that effect and no crackling or distortion. T3 impacts only the sound set by T4, it increase the overall volume a bit too. T1 has a very mild effect on the loudness, so I left it in the sweet spot position - but that's it.

Bottom line, the highest volume I was able to set is still about 50% lower than it should be.
The IC1 is new, the CF is replaced, all the capacitors... all snugs positioned where the volume is at its highest, reception is great, but low in volume. I don't know, there must be something inside the frequency transformers, a cracked or worn ferrite core, bad internal capacitor... I am out of ideas.

[Agent24]

Unfortunately troubleshooting further likely needs equipment like an oscilloscope and such. But hey at least it works at all! You solved some interesting problems and I'm sure learned a lot.

The only other thing that springs to mind is a leaky diode or such that's causing problems under load. Basic Vdrop measurements on a multimeter won't typically tell you if a diode is leaky, only if it's shorted or open.