ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Morning all,
I've just done a bulb job (thanks Martin) and found the source of the mains hum and occasional errant behaviour due to C66 and C68 but am now just a little stuck.
It seems the bass potentiometer's slider isn't in contact anymore. I have sprayed in contact cleaner but that hasn't helped and it feels rather loose compared to treble and balance. It's desoldered and I'll have a closer look later and possibly disassemble it. I have emailed Ruwido. Just in case they don't help any suggestions for a supplier for these ?
There's one thing on the schematic that troubles me only because I don't understand its purpose. On the mains input there is an electrolytic and a pair of diodes all in parallel. What is this for ?
Thanks,
Jon
After Mika's reply I found http://archivedarchivedforum2.beoworld.org/forums/t/2323.aspx
I don't think new potentiometers are available. You'll need to repair it or find a donor. I've never worked on these myself but I believe that usually the tip of the slider breaks off. You can glue it back with some effort (there are pictures somewhere on the forum).
The odd mains circuit can be found in many Beomasters. It must be some kind of an interference suppressor.
--mika
You need this:
http://archivedforum2.beoworld.org/forums/p/11552/100878.aspx#100878
The filter is for spike suppression etc.Apart from replacing the capacitor, I've never seen problems here.
Martin
It seems that arrangement is a standard way of protecting against small D.C. offsets on the mains and the resultant saturation it could cause.
Nothing to do with noise or transients.
Nothing wrong with it apart from my curiosity.