Amiga 1000 NTSC to PAL conversion

[Jameson]

Hey guys,

anyone out there know anything about converting a Revision A Amiga 1000 from NTSC to PAL?

I recently acquired yet another Amiga 1000, this one is really in mint condition - absolutely no yellowing at all, everything included (except original box) and working perfectly.

So far I have recapped the motherboard, daughterboard, PSU and floppy drive. I have cleaned, serviced and lubricated the floppy drive (which reads perfectly) and done the low pass filter mod. I have one of the new Parceiro II+ with 28mhz CPU module installed and everything is working perfectly...... except composite out. Composite is in monochrome and simply awful, very poor quality etc.

The reason for this is, this is one of the early "PAL" Amiga 1000's Commodore sold in PAL regions.... which is simply an NTSC machine with the PSU swapped out to a 220v unit and a PAL Agnus installed. Commodore did not even bother to change the clock crystal.

Anywho, even though I will be using a combination of RGB2HDMI and the 23pin RGB out, I would still like to rectify the dodgy composite output. To that end I have already installed a socket to the clock crystal and installed a PAL freq unit. Now apparently there are a few resistors that need to be removed and installed to complete the NTSC to PAL conversion.... however apparently on Revision A motherboards some of the points at which these components go are not present.... but surely the signal can be picked up elsewhere, so I am hoping some knowledgeable fellow out there in the Amigaverse might be able to help get this wonderful machine outputting a useable composite.

Thx.

 

[m0c]

Obtaining a true PAL color composite video output requires more than just an 8367 Agnus and changing the 28.6363 MHz oscillator to 28.375 MHz. The necessary color burst is missing. It can be added with the circuit below. It basically reconfigures the MC1377 video encoder to PAL by adding an extra crystal oscillator for the 4.433619 MHz color burst and by changing/removing some of the surrounding passive components.

About 38 years ago, this circuit was being sold as a "piggy board" kit and I am fortunate enough to have one installed in an A1000 that I use for (PAL) genlock purposes.



I hope this helps and that the pictures are clear enough. The two black wires belong to the Rejuvenator.

 

[Jameson]

Thanks for that mate - very illuminating. I just spent hours, with help from David Dunklee of Pareiro fame, trying to figure this out. There is a website (Jani) that has a bit of a brief guide that gives the impression that you can convert certain NTSC A1000's (not all revisions) to PAL by removing some passive components, adding some and replacing some (6 in total I believe), snip pin 20 of the 1377 to set it to PAL mode and Bob's yer' uncle..... long story short, it doesn't work.

So obviously the missing ingredient is the missing colour burst clock generator.

One more question though..... if you have one of these "hyrbrid" NTSC/PAL Amiga 1000's with a PAL Agnus, and a PAL Clock generator..... exactly WHAT is the video output? NTSC obviously, but what effect is the PAL Agnus and PAL clock generator having on the video output?

 

[m0c]

if you have one of these "hyrbrid" NTSC/PAL Amiga 1000's with a PAL Agnus, and a PAL Clock generator..... exactly WHAT is the video output? NTSC obviously, but what effect is the PAL Agnus and PAL clock generator having on the video output?

As you probably know, the early A1000s for the European market were nothing but American NTSC machines with a rev. A mainboard (with WCS daughterboard), 220V PSU, a PAL Agnus and some minor changes to a few passives near the MC1377. They didn't even bother to exchange the NTSC oscillator block. To my knowledge, the only visible effect of a PAL Agnus on the composite video output is the higher vertical resolution. I've never looked into the purpose of the changed passives, as the composite output was still very much black&white -- the MC1377 datasheet might shed a light on this.

Changing the oscillator block to 28.375MHz will make a "hybrid" PAL machine capable of (PAL) genlocking via the RGB port. It will not magically add color to the composite output. With all due respect to Jani, but his hack won't work

 

[Jameson]

"With all due respect to Jani, but his hack won't work " Yes, you are right - I jusr tried his mod and had to revert it back as it didn't work.

 

[m0c]

The composite output of the early A1000s is crippled anyway. The picture of my 1985 rev.6 NTSC A1000 connected via composite to an A1080 monitor is B/W too.

On photos of a "real" PAL mainboard (with onboard WCS), the 4.433619 MHz crystal is clearly visible.