How can you convert the Polyvox Rev.16 back to NTSC?

[Corredor X]

Greetings from Brazil! =)

 

As many of you may know, some of the earlier models of the consoles released here by Polyvox were actually the Rev.16 converted to PAL-M. I've got one of those recently and tried to get it back to NTSC, but I ran into a little problem...

 

In the later models of the 2600, the ones that were produced here, it's a very simple operation. We remove the little conversion board, a capacitor and change the crystal oscillator for a NTSC one. But the Polyvox people made more modifications in their Rev.16 batch, changing more resistors and stuff. Because of that, all I got is a B/W image. I looked at the 2600 schematics and replaced a missing resistor (R234), also remade a line that was interrupted and removed a "jumper" between two points, but still no colors, so something is missing.

 

I'd like to know if anyone here successfully performed this modification and could tell me what I need to do. Thanks in advance =)

[AndyCaruso]

Hi.

 

I'm from Brazil too, and got an Atari with the same board revision. I found very odd the cristal on my board is 3.57mhz. Is yours the same?

 

Best regards,

André

[Corredor X]

 

I'm from Brazil too, and got an Atari with the same board revision. I found very odd the cristal on my board is 3.57mhz. Is yours the same?

 

Hello, André =)

 

Yeah, it was the same crystal. In the end, I gave up of converting that particular unit back to NTSC, I ended up buying an Atari Jr and modding it for s-video, which was my original intention for the first one.

[AndyCaruso]

Mine os giving me a black screen when I turn it on. I was wondering about to replace the NTSC cristal...

[Corredor X]

Take a look on the capacitors too, a leaked or "puffy" one could be the culprit too. One of my consoles once gave up because of a faulty one.

[Mef]

I'm guessing you guys are tapping to the wrong pins on TIA.

 

The pinout is slightly different for PAL and NTSC, so it's not just a matter of the crystal.

Check this out:

 

[Corredor X]

Actually, the Ataris we got here - at least by the time of that revision - were NTSC units that got converted with a little board to PAL-M. The TIA itself is the exact one of the USA consoles, I think the Rev.16 ones were actually USA units that were imported and converted. The later revisions suffered the same fate, even the ones produced here; the circuit is almost the same of american units, but with another crystal and the extra board. To convert those back to NTSC, you just need to change the crystal, take out the board and make a little bridge at one point of the board, I think. But the Rev.16 has some other components removed and maybe changed, so we don't know how to properly change it back