Excessive electrical noise and popping sounds from Panasonic RC-6551

[nx_2000]

I have a Panasonic RC-6551 emanating rather obnoxious noises when it's plugged in. I uploaded the linked video so you can hear exactly what's emanating from the speaker. In addition to all the popping sounds, there's also a pronounced buzz emanating from the transformer than may or may not be related. When I shot this video, the sound was emanating from the speaker even if headphones were plugged in. Immediately afterward, I plugged the clock in again, and after a couple good whacks (percussive maintenance), the sound static WAS redirected to the headphones... with only the transformer buzz remaining.

Be aware, there is a brief but dramatic increase in volume 37 seconds into the video when I turn on the radio.

I'm reasonably competent when it comes to fixing mechanical issues with these clocks, but I'm not electronically inclined so I need your help in diagnosing and fixing this problem.

[Troy]

mmm sounds like a good going over with contact cleaner is the the thing here, inside the vol knob in the the tuner some times the vol knobs don't have holes in them so you must carefully drill a small hole on the casing of the vol knob, be careful not to penetrate the drill into the back ,spray all switches ,best results i found if you rotate the dial or keep switching the switchers as you you spray the contact cleaner around ..

as for the transformer you will have to remove the metal case before you can do this...https://www.flipclockfans.com/forum/...y-transformers

[Mackey]

"percussive maintenance" that's a good one.
Troy (above) may be right on and that's the first thing I would try too.

But to me it sounds like you have a loose wire and/or something is contacting a point on your circuit board.
I think I can see the light flickering in time with the sound too. That would mean a change in voltage or short circuiting intemittently.

If it were me, I'd first go through and start moving wires around to see if I could intensify or cause the sound to cease.

Then I would disconnect the clock motor and see if the sound persisted, just to rule out that as an issue.

If that didn't work I'd totally disassemble , blow it all over with compressed air, clean the board as best I could. I'd really examine the board looking for debris, loose connections.

If that didn't work I'd disconnect the light to see if it was the problem.

It could be a bad capacitor. An old TV repair guy told me 9 times out of 10 you can see a bad capacitor as the "can" seems to have swollen, particularly visible on the top and/or it's leaking. (from what I can see ... none of yours looks bad though).

of all the above, I'm still thinking something (could even be a just piece of loose soldier) is touching your circuit board.

Good luck!

[nx_2000]

Thanks for the replies, you two. I'll take it apart next weekend and have a closer look. I did visually inspect all the caps last time and they looked good... but you guys have posited several plausible faults.

[nx_2000]

I wanted to revive this topic as the random crackling problem has materialized in my other RC-6551, which for the last several years has been operational as the clock I actually wake up to every morning. It seems entirely unrelated to any dials and switches. I've also noticed the problem takes a while to return if I unplug the clock for an extended period. It leads me to believe this is a capacitor issue, but short of visually damaged caps, I don't think I have the skill or equipment necessary to fix the problem.

[Performa]

I wanted to revive this topic as the random crackling problem has materialized in my other RC-6551, which for the last several years has been operational as the clock I actually wake up to every morning. It seems entirely unrelated to any dials and switches. I've also noticed the problem takes a while to return if I unplug the clock for an extended period. It leads me to believe this is a capacitor issue, but short of visually damaged caps, I don't think I have the skill or equipment necessary to fix the problem.

Grab yourself a multimeter (even a value bin beater model from harbor freight will do for this) and connect it to the lines on the speakers to see what the voltage looks like. From there, you may be able to trace the issue back from the speaker through the various components until you find your bad cap, trace, or wire. Just stop before you get to the power supply- if the strange voltage spiking seems to go all the way there, you may have your culprit too. However, since hitting it seems to 'fix' it in a sense, that leads me to think it's something wrong with either a cap or wire. Once you've isolated (roughly) where the errant voltage is slipping through, it will be easier to outline a plan of attack to get your clocks working as they should.

Good luck!