[QuadList] ot Help with a Betamax Circuit Diagram

[Dennis Degan]

		On Jan 13, 2012, at 4:54 AM, David Dean wrote:

 >Whilst everybody is talking about Circuit diagrams I would be  
grateful for any help with a Sony Betamax SLO 420, The machine will  
not load a cssette, if you wind the cassette compartment by hand it  
will then load and play. I have checked the compartment  and that is  
seeing the cassette but it is not loading it. The fault appears to be  
on the SS10 board, but all I can see it do is go into a big square  
chip and a little sub board !
 > Funilly enough it will eject the tape !
 > Thanks for the bandwith

		I offer:

	David, before you get too deep into circuitry, I'd suggest you check  
all mechanical trouble spots first.  Most of these problems are caused  
by bad microswitches, little actuators, or sensors that tell the  
electronics what state the mechanical parts are in.  Often, these  
sensing devices fail or get out of alignment, preventing the cassette  
tray from loading, for example.  I'll bet that there is a microswitch  
inside that should be actuated when a cassette is loaded.  My guess is  
that this microswitch is not working properly.  A tipoff is that you  
indicated that the machine will correctly eject the cassette.
	Though electronics can fail, it is not first on the troubleshooting  
list.

			Dennis Degan, Video Editor-Consultant-Knowledge Bank
					     NBC Today Show, New York