Re: Monitor problems

["Frank Townsend" <ftownsen@iamdigex.net>]

Thanks, Paul, for the suggestions!

The only daunting thing about going about this is the sheer size of the
monitor:  at about 77 pounds it's difficult for (me at least) to physically
hoss the thing around to work on it.

It seems such a fixable problem, though and a shame to just throw it away.

Thanks again for the write-up!

Frank Townsend

"Paul Grammens" <grammens@svn.net> wrote in message
3d2b16f7@news.svn.net">news:3d2b16f7@news.svn.net...
>
> "Frank Townsend" <ftownsen@iamdigex.net> wrote in message
> news:sVxW8.5909$I02.5031@nwrddc04.gnilink.net...
> > I've had a setback in my Apple II and other computer endeavors:  my
> > venerable NEC 6FGP monitor is on the fritz.  The way this relates to
Apple
> > II is that this monitor has both D-sub and BNC connectors and a switch
so
> > that I can use it with my PC and Mac LCIII/Apple IIe card set up.
> >
> > The screen image is squashed in the vertical dimension to about 25% of
the
> > usual screen size.
> >
>
> Well... problems with the vertical ckt are easier to fix than problems
with
> the horizontal.  The vertical sweep is usually generated by a chip that
has
> a built-in heat sink. Usually just a piece of sheetmetal. It may be
mounted
> on another heatsink. It typically has distinctive "zip" pins, i.e.
staggered
> coming out the edge of the chip. Probably 16 or 18 pins, something like
> that. Besides the vertical output, it  often has sync circuitry on it.
> There are 4 wires coming out of the yoke, which is a coil on the neck of
the
> CRT. Two of them carry the horizontal sweep signal, and two carry the
> vertical sweep. So the vertical chip is usually near where those wires
> connect to the PC bd. Your problem is likely to be that chip, or possibly
a
> power supply problem with a voltage that chip needs. Could also be a bad
> capacitor. Come to think of it, that's likely. What I often do is get the
> part number off the vertical chip, look up the diagram for it, and it
shows
> the pinout. It usually has a pin that a capacitor is connected to, which
> determines the sweep rate. I also try "Technician in a Can", which is what
> we call freeze spray. Spritz the chip and local capacitors a bit and watch
> the screen, see if the vertical size changes when you spritz (obviously
you
> have to do that while it's on.)  Figure out which part is causing the
change
> and replace it.
>
> That's just generic info, may or may not apply to your NEC.  Good luck,
and
> of course be careful.
> But as long as you stay away from the high voltage (fat wire going to a
big
> cap on the fat part of the CRT) and the power supply area, you should be
OK.
> -Paul
>
>