Re: Vertical Sync Issues with modern TV

[mjmahon@aol.com (Michael J. Mahon)]

Mike Willegal replied:

>In article <20040921013815.23955.00000873@mb-m16.aol.com>,
> mjmahon@aol.com (Michael J. Mahon) wrote:
>
>> Mike Willegal wrote:
>> 
>> >   My Apple II's seem to work fine with the old Taxon monochrome monitor 
>> >I have, but vertical sync appears to be an issue with recent color TVs 
>> >(with no apparent external vetical sync controls).  Tried both an RF 
>> >modulator and composite video, but vertical sync  doesn't lock on two 
>> >different TVs.
>> >   Any ideas?
>> 
>> It's unlikely to be a scan frequency problem, since the Apple is
>> very close to standard.

<snip>

>This is getting more interesting.  It appears from an Oscilliscope that 
>the vertical refresh is cycling at 50 HZ.  The board came from ebay - 
>and is marked copyright 1978.  Did apple make a PAL type board in that 
>timeframe.  There is no rework visible, so it either has a strange 
>problem in the ls161 dividers area or was built for a PAL type 
>application.  It came with a PAL encoder board and a universal power 
>supply.
>
>The Taxon Monitor must be very tolerant of veritcal refresh rates.

Most monitors are adjustable in the 50-60 Hz range, though not all.

>What do you guys think?

I think you have a remarkable Apple II.  ;-)

It does sound like PAL scan rates--perhaps you have a very early one.
Someone from across the pond would know...

-michael

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