I have a Beolit 505 which suddenly started to sound slightly distorted on all stations. It is not the speaker because I tried another one. I think the speaker is stuck and remember reading somwhere that this could be the output transistors. According to the diagram this is TR 8 & 9 which are AC187 and AC188.

Has anyone replaced these before and should anything else be replaced?

Cheers in advance

Hi,

I have a few Beolits but never needed to work on the output stages - I'm bumping this for you anyway in case somebody more knowledgeable picks it up (this would've suited better to the vintage subforum, though).

If you have confirmed that the speaker is OK, it could indeed be possible that one of the transistors might have failed. That would certainly sound distorted. You can measure them just as you would measure silicon transistors, just remember that they often leak a bit even if they are all right.

Replace also the output coupling cap for the speaker (component no. 83). The problem probably isn't there, but I think I once read that a dying cap might be a cause for the speaker itself to eventually fail, so it would be a harmless preventive measure to do just in case.