Newsgroup: sci.electronics.repair

I have now found the source of the problem, and sort-of solved it.  The 
transport control system has a mechanism for rapidly aplying the brakes 
to the take-up and supply wheels when the system goes from fast-forward 
to stop.  This mechanism consists of a small metal lever and is armed 
when the plastic transport control plate moves into the fast forward 
position: the lever moves in sync with the rest of the transport control 
plate and removes the brakes, while also applying tension to a spring.

When a stop command occurs the motor triggers the armed brake lever, not 
via the normal gear mechanism that controls the positioning of all other 
parts (and its initial arming), but via a separate system.  The 
transport control motor, appart from the transport control gear, has on 
its axle a  paddle-wheel structure consisting of three paddles.  When 
stop is pressed, a small part of the control motor rotation causes one 
of the three paddles to trigger the armed break lever.  On my system I 
could cause this action by hand, but the motor did not apply enough 
torque to trigger it via the paddle.  I "solved" this problem by 
removing the the lever's spring and extending it beyong its limit of 
elasticity, thus increasing its length and decreasing the pressure it 
applied on the triggering mechanism.  The system works ok now, though I 
am not entirely happy with the solution.

Diomidis Spinellis - http://www.spinellis.gr


I wrote:
> My Sony SLV-E470EG VCR is now operating in a weird manner after 
> rewinding or fast-forwarding the tape.  All functions behave OK, until 
> stop or play is pressed during a fast-forward or rewind operation.
> 
> At that point a noise of a motor running without effect is heard for 
> about 4 seconds.  From that point onward the play, rewind and fast 
> forward commands do not produce any action.  An eject command will start 
> rewinding the tape (at relatively low speed) for about 20 seconds. After 
> that point the tape will be ejected.  When the tape is loaded again the 
> cycle (normal play / eject, until play / stop is hit during rewind / 
> fast-forward) can be repeated.

[...]

Unless otherwise expressly stated, all original material on this page created by Diomidis Spinellis is licensed under a Creative Commons Attribution-Share Alike 3.0 Greece License.