[Barnabas]

Hi there,

I am trying to repair a Beocenter 4000 (1985 version with two cassette decks).

There is a fault with the audio from the tuner section which is only coming through on the left channel. This is the same for both FM (including the 4 presets) and AM. It’s also the same on speaker outputs 1 and 2, and the headphone output. FM stereo is working OK (although obviously I can only hear one side of it!). The cassette, phono and aux sections are all working ok on both channels.

I have a basic knowledge of electronics and some basic equipment (iron, desoldering gun, multimeter etc.) I have checked for anything obviously wrong and inspected wherever possible for dry solder joints. I’ve had a look at some schematics found online but I’m having trouble working out the audio signal path from the tuner section and relating the various schematic diagrams to each other.

Could anyone please suggest any possible faulty components or areas to look at?

 

[Barnabas]

I also meant to add that a previous owner had installed some replacement bulbs that were obviously not correctly rated, in the two lamp holders that illuminate the display. They’ve obviously overheated as some of the surrounding plastic has melted slightly. I wondered if this had maybe adversely affected any surrounding components, although visually everything looks ok.

 

[Dillen]

Have you checked the fuses?

Martin

[Barnabas]

Hi Martin,

Thanks for your reply. I have checked the four fuses on the right hand side of the unit next to the mains transformer – they’re all fine. They look like mains fuses though rather than audio. Are there some other fuses I may have missed?

 

[Dillen]

Perhaps a bad capacitor somewhere. That wouldn’t be a first.
Put a scope to the signal path, compare left/right and see, where the signal is lost.

Martin

[Barnabas]

OK, I will investigate. No recapping has been done yet so it is very much a possibility…

Thanks again.

 

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