I want to installed a PAL / NTSC switch on my NTSC Amiga 2000 and have opened it up and located J102, the jumper that is apparently CLOSED for NTSC Amigas and OPEN for PAL Amigas.

This is definitely an NTSC Amiga, but those pads look OPEN. Do you agree? Click the + symbol at the top-right of the image to zoom way in.

http://www.flickr.com/photos/blakespot/5586840948/in/set-72157604299491786/

Or, is it closed on the underside of the board? I'd rather not take it out of the case. Should I cut into the board along the green line that seems to separate the pads, in case it's a sub-layer connection?

It seems like it's OPEN to me, but this is definitely an NTSC Amiga.

This is an A2000 Rev 6.3 board. Thanks.

(
full zoom image = http://www.flickr.com/photos/blakespot/5586840948/sizes/o/in/set-72157604299491786/
)


bp

Last edited by blakespot on 03-Apr-2011 at 09:58 PM.

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:::: Amigas: 1000, 2000 '020, SAM440ep-Flex 733

@blakespot

With most A2000 systems, a "fixed" AGNUS was used. There were several newer AGNUS versions that were switchable in NTSC/PAL, but it looks like yours is not. So the jumper is quite useless for your purpose.

Its open, btw., such jumper pads were never wired with a "sub layer connection".

Another strange thing I spotted in your picture: Your A2000 uses a 8375 AGNUS, which is normally used in A500+, A3000 and A600. Maybe its one of the "crippled" series? How many CHIP does your machine show? Some of the first ECS A2000 (1MB CHIP) used such an AGNUS, but they were fixed ones (only NTSC versions available, IIRC).

Hmm. That's unfortunate, if you're right here.

This is a 6.3 board that's ECS and shows 1MB CHIP. I got it in the early '00s fro a guy that had like 30 NIB A2000s, online.

I wanted a hardware switch because I just got a HxC 2001 SD card floppy emulator and want to use images on the SD pretty much exclusively here, but adding Degrader into that process would be a massive fail.

Is there no way to get a switch in there, even if tying to a pin somewhere? I sorely wish that the boot loader disk image for the HxC 2001 had a PAL / NTSC toggle.

Ugh.



bp

_________________
:::: Amigas: 1000, 2000 '020, SAM440ep-Flex 733

@blakespot

I don't know about the A2000, but certainly for the A1000 and the A500:

The "NTSC/PAL" link was provided to switch the crystal division ratio so that the colour subcarrier ended up at the right frequency (ie, 3.58 MHz for NTSC or 4.433 MHz for PAL). That only makes the colour subcarrier correct so that the composite TV signal output can be decoded on a standard analogue TV set/monitor. In both the A1000 and the A500, you also had to change the crystal - so you had to change the master oscillator AND the division ratio to get the right subcarrier (if you wanted to view the output on a standard TV). It was probably the same on an A2000 (same time frame, after all). If you are not using the composite output, but RGB to a monitor, the colour subcarrier doesn't concern you at all.

To switch the scan rates from 525/60 (NTSC) to 625/50 (PAL) is another matter entirely. It was handled by the Agnus chip in software. I seem to remember that one of the later Kickstarts allowed you to switch it from the Early Start Screen by toggling it with the space bar. Also you could choose an NTSC or PAL screen mode, but whichever you chose, you would get a subcarrier frequency that was determined by the hardware. Of course, that doesn't mean anything if you are using RGB output.

_________________
cheers
tony

Hyperion Support Forum: http://forum.hyperion-entertainment.biz/index.php

@blakespot

According to "The Big Book of Amiga Hardware", if you have a 8375, it isn't switchable. So I guess the missing jumper wouldn't do anything. I wonder if it will work with earlier versions of Agnes in the socket.

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X5000 / microA1(OS4.1 FE U2) / CodeBench / Imagine / Blender
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@blakespot

Quote:

Is there no way to get a switch in there, even if tying to a pin somewhere?

AFAIK, not. You could try to trace the jumper pad up to the pin were it connects to Agnus, but I fear it is connected to the right pin. If it is so, the switch ability of your 8375 Agnus is disabled internally (as stated in several documents regarding Agnus).

@thinkchip

Depends on the version. Some OCS Agni were switchable, newer ECS Agni were, too. There is a list of the Agnus versions somewhere, stating which are switchable and which are not. But I dont remember were it was. Doing a little search may help