Re: Multinorm TV woes - no NTSC color display

[Linards Ticmanis <ticmanis@gmx.de>]

Bryan, sorry for sending this by e-mail. That was not my intention. I'm
resending it as a news article.

Bryan Parkoff schrieb:

>     It is not a good idea to swap 14.25MHz osc chip to 14.3MHz osc chip 
> because Apple II motherboard has two different revisions.  First revision 
> with 14.3MHz osc chip is designed for NTSC only.  Second revision with 
> 14.25MHz has a special circuit for PAL on the Apple II motherboard.

Can you describe this PAL circuit. I know that the IIe has a PAL version
motherboard that is very different from the NTSC IIe.

But my computer is a II+, not a IIe. What is the difference between NTSC
II+ motherboard and PAL II+ motherboard beyond the jumpers and the quartz?

> I suggest to use Apple II motherboard which it has PAL circuit so you 
> don't need PAL color card unless it is an alternative choice.

As far as I know, there is no II+ that can do PAL color without a card.
Please correct me if I'm wrong.

>     No, it won't work.  If you use NTSC monitor with PAL circuit 
> motherboard, it will not work.  The only way is to use NTSC monitor in 
> Europe.  You will need to have 120 volt to 240 volt converter so you will 
> have 60 Hz on NTSC circuit motherboard and NTSC monitor.

The Apple motherboard should not care, should it? It gets only DC
current from the power supply, not AC. My monitor (TV set) is a 220
Volt/50 Hz model already.


>     I do not think to lose color if 60Hz is incompatible to 50Hz.  It is to 
> deal with 262 lines and 312 lines.  If NTSC monitor is connected to PAL 
> circuit motherboard, I am sure that NTSC monitor will roll up because of 
> difference between 262 lines and 312 lines.

The monitor is a multinorm model, it has no problem with 50Hz or with
60Hz. I tested with a DVD player.


>     I am not sure, but I know that some monitors have a support of NTSC/PAL 
> switches so it should work as long.

The monitor should switch automatically, but it doesn't with the Apple.
There is no manual switch.

>     It is deep technical issue how Apple II produces video to the NTSC 
> signal.  It is done by 14MHz which it sends one bit by one bit stream 
> through the serial video cable to the NTSC monitor.  Then NTSC monitor picks 
> up a group of four pulses to create color reference using 3.58MHz.  It has 
> to restrict at 262 lines for NTSC.
>     It has a deep explanation of technical video in the "Understanding the 
> Apple II+" on chapter 8.  You can find PDF format somewhere when someone 
> posted it on the newsgroups earlier.

Thanks for the hint. I myself was the person who made that PDF, thus I
have read it already. But I agree it is a very good book.