RCA Victor Solid State radio

[timl15]

I’ve had this RCA Victor radio (model RJC47W, serial # 74161348) for a couple of years now, play it every day, sounds fantastic, replaced a more modern radio that I had in the kitchen. Lately it’s developed a sound issue, when listening to the radio (AM or FM doesn’t matter, can go days with no sound issues, but other times starts having issues within minutes), it will start to create a brrrrrrrrrrrrrr sound or bzzzzzzzzzzz sound, the radio station volume stays the same during these instances. I thought it would be an old paper capacitor that has gone bad, but when I opened it up, found out it was built with all the newer caps, so now I’m not sure this is my problem.

I have very limited knowledge on electronic repair but am trying to learn. I do not have a Z Meter to test the capacitors, does anyone know what could possibly be the issue, and if so, could someone tell me what could be wrong with this radio by looking at the attached pictures and pointing me in the right direction.

I also looked online for a schematic for it but was unsuccessful.

Tim

[ctc17]

Nice radio! Is the top pushed up on the big blue capacitor? Its hard to tell from the picture but it doesnt look flat.
Is it a loud hum or some kind of interference?

[timl15]

All the caps are flat, even the big one (they all look normal).

There is no interference (adjusting the dial/station tuner, does nothing to solve the sound issue), and the radio does not hum (like a tube radio does when it's caps are bad).

[Reece]

Are you absolutely sure the noise originates in the radio or is it external interference? Plug another radio in alongside and see if they both make noise.

If it's the RCA at fault, it would surely help to have the schematic but that might be tough on such a "new" set. Couple of things to try: with the board out and the radio playing making noise, bridge each electrolytic temporarily one by one with a similar sized one to see if there's a change. Be sure you have + and - same as on the set. Studying the board you might figure out how to signal trace it to see first if the noise originates in the power supply or starting in the audio output stages and working backwards, seeing where the noise stops. You could use a computer amplified speaker as a signal tracer. A shielded input lead to the amp/speaker would have the shield connected to the RCA's common rail, and the center lead from the amp/speaker would go through a small cap (like .01mfd) to a probe that you try on different stages in the RCA.

[bgadow]

That's my kitchen radio, too! Actualy, the cabinet on mine is slightly different. Glad you posted the inside view as I've never had a need to pull the back off mine.

That sure sounds like a cap problem to me. I enjoy recapping these solid state sets as they aren't too bad to work on. I've noticed similiar noises on other transistor radios-they become prone to either motorboating or overloading when the volume is increased slightly, that sort of thing. Recapping fixed it. I have noticed that my RCA tends to pick up interference rather easily. It sits on the microwave and the current unit we have doesn't cause much trouble but our last oven would make it unlistenable. Then, recently, we noticed a slight staticy noise which I traced to the CFL bulb in our ceiling fixture. That was an easy fix: replaced it with a good old incandescent.

[Findm-Keepm]

The caps are almost certainly dried out - RJC = 1968 model (I have a wedgewood blue model with an RLC prefix, a couple of years younger). 43 is old in capacitor-years.

The axials up on end are originals - I had the same in my set, which had low FM volume and the ubiquitous hum. A recap solved all the problems, except one - the radio cannot pick up any quality broadcasts, just rap, Top-40, sports radio, and cookie-cutter country.

Cheers,

[MelodyMaster]

While it's most likely the input filter capacitor that's dry, don't overlook one or both legs of the rectifier going bad. (leaky with back-conduction) This will introduce buzz rather than hum.

[timl15]

Thanks everyone for all the info, I think I will replace all the capacitors and see what happens. A couple of questions (since I’m still learning this electronic stuff). There are 10 capacitors that I am familiar with, and then there are 2 of these silver rectangular components (see attached pics), are they also capacitors? Or a resistor? If a cap, what do I need as a replacement (there are 2 of these on the circuit board).

About the diodes possibly being bad, what replacements should I use? Radio Shack has a bunch of different ones, a couple that I looked at are 3amp barrel diodes, Cat# 276-1141, and 276-1144 and there are numerous other ones, would any of these that I listed be good replacements or what would be your recommendation?

Also with diodes, the newer ones have a silver band around them, the ones in my radio do not, they are barrel shaped with one end having a conical shape would this be equivalent to the silver band on the newer diodes? Match the silver band on the new diodes to the conical end on the old diodes?

Tim

[bob91343]

Those are capacitors. marked with the value.

As for the diodes, you aren't clear enough for me to visualize the appearance of the ones you have.

[timl15]

Thanks, so those silver caps would be .1 MFD (since it isn't marked mfd) or PFD?

Does this picture help in identifying the diodes?

[MelodyMaster]

Originally Posted by timl15

Thanks, so those silver caps would be .1 MFD (since it isn't marked mfd) or PFD?

Does this picture help in identifying the diodes?

The only capacitors we're worried about are the big blue ones, with values in 1000's of Mf. Those silver caps, and the ceramics bridging the diodes etc. will almost never fail. The filter input capacitor, the one most likely to be dry since it's subject to high current at turnon, is very obviously downwind from the diodes (next to the heatsink) - follow the traces. (Not the 100 Mf BETWEEN heatsinks, but the 1500 Mfd or so beyond that.) It looks like there's two that you want to change.

[Reece]

And study, and be absolutely sure, that you get + and - back in the right holes when replacing the electrolytics.

[timl15]

An update, I finally ordered and installed the caps that MelodyMaster recommended. I also decided to refinish the wooden cabinet since I had everything apart, it had a tired and lackluster look to it, I used Howard’s Restore-A-Finish cherry color and finished it off with 3 coats of Tung Oil.

The radio now looks as good as it sounds! Thanks for everyone’s input! I really appreciate it, and couldn’t have done it without all your guys’ knowledge and guidance, thanks again!

Tim

[radiodayz]

Congrats, Tim, and nice job on the cabinet restoration, looks great! I have a similar-looking one, with a similar issue; sounds great at low volume, but turn it up to normal listening levels and brrrrrr! It's on my to-do list.

Keith