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Wigglyamps
23rd Jun 2019, 14:14
Bit of a long short and strictly speaking not internet related, however, just wondered if any clever types might have an answer to my question.
I have just bought a Bush DAB radio cheap at a carboot sale (I know, caveat emptor) when it's playing DAB or FM radio there is a constant loud shriek which is unaffected by the volume button (you can hear the music in the background)~, but, when in bluetooth speaker mode it is fine. Only spent a fiver so it's not the end of the world but it's a nice little unit and it would be nice to get it working properly.
Thanks
Wigglyamps

G0ULI
23rd Jun 2019, 17:01
The shriek is probably feedback being caused by a dodgy capacitor between the DAB and FM tuner and the amplifier section. Impossible to diagnose further wirhourt a circuirt diagram.

The amplifier,section must be okay because music is playing via Bluetooth. The tuner section is okay because you can hear stations in the background. Therefore the fault must lie between the tuner and amplifier sections. Electrolytic capacitors are the components most likely to fail. They look like little plastic cans stood on end in the circuit board. The exact value for a replacement is generally not critical (+ or - 20%) just so long as it physically fits and the voltage rating matches or exceeds the original.

jimjim1
23rd Jun 2019, 21:13
https://www.vintage-radio.net/forum/

Wigglyamps
24th Jun 2019, 05:38
The shriek is probably feedback being caused by a dodgy capacitor between the DAB and FM tuner and the amplifier section. Impossible to diagnose further wirhourt a circuirt diagram.

The amplifier,section must be okay because music is playing via Bluetooth. The tuner section is okay because you can hear stations in the background. Therefore the fault must lie between the tuner and amplifier sections. Electrolytic capacitors are the components most likely to fail. They look like little plastic cans stood on end in the circuit board. The exact value for a replacement is generally not critical (+ or - 20%) just so long as it physically fits and the voltage rating matches or exceeds the original.
Thank you so much for the help, I will do some investigation.

finncapt
24th Jun 2019, 11:34
One can often tell a blown electrolytic capacitor as they bulge at the top.

I have ressurected several flatscreens by replacing bulged capacitors.