in Search
Untitled Page

ARCHIVED FORUM -- April 2007 to March 2012
READ ONLY FORUM

This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 11-29-2010 4:44 AM by MartinM. 0 replies.
Page 1 of 1 (1 items)
Sort Posts: Previous Next
  • 11-29-2010 4:44 AM

    • MartinM
    • Not Ranked
    • Joined on 08-07-2008
    • New Zealand
    • Posts 49
    • Bronze Member

    Beocord 7000 Repair/ Upgrade Project

    My Beocord 7000 was in need of some attention. When playing a tape the sound quality was not great and had a very pronounced “warble” to it. There was also an annoying mechanical ticking noise. So with the prospect of having to pull the machine apart, why not replace the belts and all the Capacitors at the same time. Replacing the caps was out of interest as I’d never done this before on a cassette player. Why not see what sort of sound improvement could be had from doing this.

     Above image of BC7000 head unit. While holding down the Stop button, press the Play button. This engages play mode without a tape being present. This is intended for cleaning the head and rollers but is also perfect for viewing what the unit is doing mechanically. The source of the ticking sound, and also the cause of the warbling during playback was immediately apparent.

    When play is engaged, the head moves forward along with a metal plate which pushes against a small plastic post attached to one of the brake arms. The brake arms can be seen as the white angled levers in the center of the photo.  The left arm moves in time with the right via a small gear between the two. What should happen is that when the mechanism is fully forward, the brake arms have been moved sufficiently to clear the small upright teeth on the edge of each tape spool gear. However, in my case this was not happening.  The arms were just a fraction too low causing them to contact the upright teeth resulting in the ticking noise and uneven rotation of the tape spool gears.

     

     My solution was to carefully “Pre-Shrink” some heat shrink to a slightly smaller diameter than the plastic post (This would ensure a tight fit and no glue required). Then carefully push the heat shrink over the post effectively increasing its diameter (only a very small increase is required). When the metal plate moves forward on Play, the increase in the posts diameter causes the brake arms to move further forward, beyond the path of the teeth mentioned. Voila, fault fixed!

    There are four belts to replace:

    One that drives the Tray; One that provides drive from the motor to the tape mechanism; One that drives the two large fly wheels and one that drives the tape counter.

    Lower recapped control board. All caps here replaced with Nichicon PW.

    Upper recapped main board. All caps in Audio path replaced with Nichicon KT and FG. All other caps replaced with Nichicon PW. All caps in PSU replaced with Nichicon PW.

    Note:  The upper board is quite large and extra care must be taken when handling it as it flexes quite easily and would not take much to damage it.

    The Becord now plays perfectly. The sound is clearer than before, particularly in the treble. It brings a smile to my face every time I play a tape on this deck now.

     

    Filed under:
Page 1 of 1 (1 items)