From NTSC to PAL Najm arabic 65xe

[somacast]

hi,

 

I posted a few topics over the past years and many members were kind enough to support.

 

long story short (please check my old threads if you want details) I bought a few years ago Atari 65xe arabic (Najm) from a guy who claimed that it was working however it got blackscreen, a real stubborn one , tried all troubleshootings even gave it recently many hours to test its logic behaviors, replaced several main ics, nothing,  black screen 😀 

 

so i went and bought an NTSC board, works, plan was to convert it to pal and call it a day, the problem now is beyond GTIA swap.. i found out that its different from back side, ie missing a port compared to PAL, and 2 ics are not used here in NTSC  ! 😞

 

questions: 

 

what to swap other than arabic rom chip & GTIA ?

 

any source for bottom shell ?

 

any better ideas? 

 

thnx

[Rybags]

There's more than that - PAL also uses a seperate crystal to generate the colour clock base, which gets fed to a pin on GTIA which is otherwise unused on NTSC.

Also I think there's an IC that helps keep the system clock and colour clock synchronised.

 

The motherboards are usually different to accomodate these changes - someone else might be able to verify that all XL/XE motherboards will differ between PAL/NTSC.

[somacast]

Thanks alot , I really in that case care more about having my Najm rom running, so i wouldn't mind (if its to difficult to PALize it 😀) to have an NTSC arabic 65xe .. i guess the Basic and others aren't region locked ? I hope..

[Rybags]

Are you sure it's NTSC?  The only region remotely arabic that used NTSC is Western Sahara (assuming the Wikipedia map is correct)

 

Basic is same regardless of region.  And the OS should work with both systems as well, from XL onwards the OS will adjust certain parameters to suit the TV standard in use.

Edited July 20 by Rybags

[somacast]

7 minutes ago, Rybags said:

Are you sure it's NTSC?  The only region remotely arabic that used NTSC is Western Sahara (assuming the Wikipedia map is correct)

 

Basic is same regardless of region.  And the OS should work with both systems as well, from XL onwards the OS will adjust certain parameters to suit the TV standard in use.

sorry I might have not explained things well.

 

I do originally own PAL arabic xe65 , the one I have posted many times about.

 

The NTSC is a regular english 65xe is the board I just bought, however it doesn't fit 100% into the bottom half of the casing due to a different back slots arrangement (it has one less socket not sure maybe cassette interface)

 

so i wanted to just transplant the arabic rom from the PAL blackscreen original motherboard to this new NTSC working English one .. I hope it makes sense now.

[Rybags]

Just transferring the Rom chip from one (non XEGS) XE to another should be no problem (aside from the fact most aren't socketed)

 

The extra slot at the back of some boards would be the ECI - it's next to the cart slot, similar form but smaller size.

[somacast]

Nice , thanks

 

the problem is that it wont fit in my shell, i need a new ntsc shell to take lower half

 

and yes you are right, nothing socketed,  i though of socketing it all to try out my other ics to know whats wrong with my original board .lol

[Mq.]

To convert a motherboard from PAL to NTSC or from NTSC to PAL, you need to do three things:

- replace GTIA (separate version for PAL and NTSC)
- replace Antic (separate version for PAL and NTSC)
- build a completely different clock circuit with different quartz resonators and a different connections

The remaining components of motherboards do not require changes, both OS-ROM and Basic-ROM remain the same for PAL and NTSC.

 

The first two points are simple and you just need to replace the integrated circuits.

The topic of the clock, however, is more complicated and you have to use electrical diagrams and simply build it from scratch.

 

In your case, I think it would be best to just repair the original motherboard.

 

Alternatively, buy another motherboard to replace it. There are two types of motherboards that differ in case shape: with an ECI connector and without an ECI connector. This is the connector next to the cartridge and this is the only thing you need to pay attention to when looking for a replacement motherboard.