I need help !!

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1 total messages Started by Ben Hodson Fri, 23 Oct 1992 09:45

#21

Author: Ben Hodson
Date: Fri, 23 Oct 1992 09:45

27 lines
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Hi,

I need someones help.  A couple of days ago I fitted a ST506 drive to my A310
(it was cheap OK).  But when I turned the computer back on the screen appeared
with a very heavvy yellow cast.  Upon examination of the RBG monitor socket
with a scope there is no signal on the 'blue' output.  Tracing the signals back
they appear to go back to a group of 6 transistors 2N3206 arranged in 3 pairs
of 2.  Looking at these there is a signal missing on the base of the 'blue'
pair.  This signal (by comparison to the others) should be a combination
of frame and line pulses with picture information superimposed on top, instead
I am getting just the frame and line pulses.  It seems that the bases of these
three pairs are connected 2 connected bases to each of the R G B outputs of
the VIDC chip. Is it probable that my VIDC has gone west.  Any help or
suggestions would be appreciated.

Even better (well in addition to the help) would be a copy of the circuit
diagram surronding the VIDC to the actual outputs with what I should find
at various places.....a serice manual.....that what its called...

Hhhheeeee
         lll
            p
            p
            p  :-(


Ben Hodson,   hodsonb@prl.philips.co.uk  Tel 0293 785544

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