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
Hi all,
I have a 1992 MX7000. It has great picture and sound except for one thing: very noticable buzz through the loudspeaker, getting louder the lighter the picture is. The buzz gets louder/softer with te colume control. Pressing mute makes the buzz disappear completely.
What can I do about it? I am suspecting bad caps in the power supply.
First step I'd take is replacing caps in the +/-5V , 8V and 15V PSU as trouble seems to start in the pre-amp or maybe tuner (buzz reacts to vol control so is injected before that)
Am I on the right track?
My smaller MXs do that as well (one of them real annoyingly). Never got around to investigating, but I suppose it is tired power supply reservoir caps allowing too much ripple, which is then injected into audio at some stage. My MX6000 which I repaired/recapped in 2008 or something doesn't suffer from this.
--mika
Thanks for the reply tournedos. Your story also points to the psu being the culprit. Did you recap the entire mx6000 or just certain parts?
I remember surprisingly little of anything from 8 years back!
I believe I replaced all small voltage electrolytics in the power supply area (there aren't that many after all, maybe a dozen). Not sure about the primary main cap, which probably is 400V or so. Remember that this cap and the tube may keep their lethal charge for days... this old workshop may be helpful even though the pictures have expired:
http://archivedarchivedforum2.beoworld.org/forums/t/10557.aspx
Disregard the component numbers though, 6000/7000 has a slightly different, newer chassis.