Apple B&W monitor schematic needed G090S

Roy J. Tellason rtellason at
Wed May 28 15:17:12 CDT 2008

On Tuesday 27 May 2008 21:49, John Robertson wrote:
> Anyone have this schematic for the Apple B&W 9" monitor? I have one that
> I am using, but the screen bias is way off so the screen is overdriven
> (horizontal retrace lines showing). Need to find if it is an adjustment
> or a bad/leaky capacitor.

No schematic,  but look and see if there's a small board on the base of the 
CRT.  Usually is on most stuff of relatively recent manufacture,  and that's 
where they'd put the adjustment,  or at least they do with color stuff.  
You'll also find the pins of the CRT labeled in many cases,  which makes it 
easy to determine the bias of the tube -- cathode voltage and g1 voltage 
should be very different,  at least 20-25V for a mono monitor,  maybe even 
more,  depending on the HV.  Measure those and post back and we'll see what 
it looks like from there...

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ablest -- form of life in this section of space,  a critter that can
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M Dakin

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