Beocenter 3300 switchbank disassembly?

[Nick R]

Hi folks, I’m looking for some advice to help with restoring a Beocenter 3300.

I’ve replaced fuses and insulation, powered up, tested, cleaned, lubricated, repaired hinges and got a nice working unit on my hands.

The one remaining problem I have a with the main selector switch assembly. All the buttons work and latch in when pressed, but about half of them don’t unlatch when the power off button is pushed. So I disassembled  the center and extracted the button unit intending to clean and reset the buttons. I’ve read a few forums that says to pull the buttons apart and deoxit, grease the mechanism and make sure it’s working properly

My problem is I can’t see how to disassemble the button bank?! It looks like a sealed unit and I’m hesitant to start prying plastic seams apart because I’m sure it’ll just break.

Anyone know how to strip down one of these button modules properly?

[Dillen]

Two different switch banks can be found in Beocenter 3300.
One cannot be easily diassembled – and it’s usually not necessary. Most will respond well to a shot of contact cleaner and a little exercise.

Martin

[Nick R]

Hi Dillen, thanks for your reply.
It looks like I have the kind that is not easily disassembled, I couldn’t see any way to do it without breaking the plastic.
I’m not sure where or how to get to the contacts, they seem buried in the unit. And anyway the actually switches works fine, the problem is some of them don’t unlatch when you push the off button. To me that suggests there’s some spring loose or maybe some cam or latch that needs tending to.

do you know if these two kinds of switch bank are I interchangeable ? If I found a replacement does it have to be the same kind?

cheers!

[Dillen]

They are interchangeable.
But if yours is the version with the white “see-saw”-arm between the switch rows, check that it doesn’t bind.
Else – give it a good dose of contact cleaner to shift any dry lubricants in the release mech.

Martin

[Nick R]

Cool cheers, I’ll give it hell with some contact cleaner and see if that loosens it up.

[Nick R]

Well I flushed it with contact cleaner and it works a lot better. Not perfect but it now unlatches 9 times out of 10, which is much better than none out of ten.

Now I have the next problem. With the switch set to mono I get sound through both channels, the balance , bass and treble sliders work perfectly with only a hint of scratchiness.
But when I switch to stereo, the left channel is completely dead, but the right continues to work fine. The balance slider still fades out the right channel but nothing from the left. Same story on phono, fm or am, right is normal, left dead. Switch back to mono and both channels perfectly fine.

Anyone experienced this or have any ideas? I’d start by cleaning and checking the sliders but I can’t work out how to release the panel!

[Mark-sf]

To narrow down where the fault lies try all sources to see if the channel is missing from all or just one or more. If all, then I would look at the preamp area prior to the mono switch and check for bad solder joints especially a the board connectors.

[Nick R]

Cheers, yes it is on all inputs. So I’ll look at the joints and connectors upstream.

[Author]

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