The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Hi guys, superb forum. I've just bought a new Superstar 3900el. It's the new release with blue led readout and illuminated nightlight front panel(like the cobra 200). Anyway, everything works as should, but there's an annoying quiet but audible high frequency continuous tone emanating from the radio that can be heard at all times(especially when squelched). It sounds similar in frequency to a "car door open" warning buzzer, but obviously nowhere near as loud. Any ideas please guys? I have a schematic handy if this helps. Cheers and best regards. Damian

The buzzing noice comes from the inverter converts 3.5 Vdc to 150-170 VAC for the EL faceplate lighting.The invertes is a little metal box mounted at the left side (component side up)I think you must change a cap inside the metal box.Perhaps another can tell little bit more.

Dxswe - You're a good man. Are these inverters prone to becoming faulty like mains inverters do you know? Thanks for the response mate.

I think CRT had little trouble with that model.I think a capicator must be change in the little metal box.I don't remeber which it is.

I have one in at the moment and after changing the capacitor to a 220uf It's still the same.

my experience with EL is that all radios with it are prone to this problem. and i've seen a high failure rate as well, at least with cobras anyway. i know that full lighting depends on perfect contact of the "layers" in the faceplate, that make up where the lighting comes from. i've seen several where the lighting is not even throughout all of the characters, and buzzing or high pitched whine, and when pressure is applied where the lights aren't working good, it affects the noise, sometimes making it go away. i think EL sucks! and in those cases, the whole nosepiece has to be replaced.

Hi
can anyone tell me if this backlight problem has been fixed with the audio sound coming form the small metal box

The answer is, NO but they don't fit it to there newer radios.
Unplug it and do without the front light, it's the only way to shut it up.