PAL amiga in US, help!!!!

[Peggus]

Help

I was just trying to hook up my old PAL A1200 to my inlaws entertainmentsystem. They have a 40inch tv and a serious sourround amplifier, droooooooool!!

Anyway I'm not getting any color when using the composit output. I can't use RGB cause they don't have any RGB or SCART inputs. And I'd prefer not to use the RF modulated outputs.
Does anyone have any idea why I'm not getting any color? The composite color was working in europe.

Another problem I'm having is the whole NTSC PAL thing. My Amiga automatically boots in PAL mode and many games revert to PAL mode even though I've booted up in NTSC, this is a big problem since the tv can't handle PAL.
 Is there any way to hardwire the amiga to NTSC?

Grateful for any help
Peggus
 

[Oli_hd]

Hi,

Is there any way to hardwire the amiga to NTSC?

Yes, I dont know what it is on AGA Amiga`s but on fat Angus Amiga 2000`s and 500`s there are two pins, one is PAL and one is NTSC, I think the one pin is earthed (Or pulled up) to force it into that mode.
Dont know about the AGA chipset though....

As for the composit thing, I have the same the other way around (NTSC system in the UK), It must be a timming problem (Change in crystals), There is something like .03Mhz difference between an NTSC and PAL Amiga, Again on the OCS/ECS chipset you chanced the crystal to correct this but I dont know about AGA.

So there you go, Hope that helped you, Probably didnt though  :-D

[Ilwrath]

re: Hardware NTSC/PAL- (I grabbed this from some old website)
No, but if you're really motivated, you can rig this up. My thanks to Tetsuo Oda and Byron Montgomerie, who provided the information that connecting pin 41 of the Alice custom chip to ground causes the A1200 to default to NTSC, while pulling this pin high (disconnecting it from the motherboard and connecting it to +5V through a 4.7k resistor) will make the default power-up state PAL. I would point out that making a modification like this on a surface-mount chip is difficult at best.

As for the Amiga booting in the wrong mode...  Why not use Degrader to force it into NTSC, though?  Go early boot menu (both mouse buttons, hit space to get NTSC), then boot no startup, run Degrader with options 60hz + 60hz System and select "Survive Reset".  Poof, the Amiga reboots as an NTSC one until you cut the power.  You can then cleanly play games that require autoboot/reboot.  Should get 95% or more working.

As for composite losing color...  I don't know why that would happen to you... unless you have the composite output hooked to a wrong input on the TV.  (Some TVs use separated lum/chrome input, instead of the single color composite)

[Rigger]

http://wonkity.com/~wblock/a1200/a1200.html

[Ilwrath]

@Rigger-
Hmm... So it is.  My apologies for not attributing to Warren Block.  I bow to his knowledge on quite a few Amiga hardware things.

[Peggus]

Thanks for all your help. Now where did I put the solderingiron  :-D

[tonyw]

It probably won't work. You will have to change the crystal as well. There are several differences between PAL and NTSC:
Horiz freq: PAL15625 NTSC 15750
Vert Freq: PAL 50 NSTC 60
Colour encoding: different (what the link selects)
Colour frequency PAL 4.43361875 NTSC 3.58-something.

Most TVs will display the different H and V signals withour problems, and some will switch colour automatically, too. But if it's a fixed frequency colour set, you've got to have the PAL/NTSC switching right as well as the frequency.

The colour frequency comes from the crystal in the computer. PAL Amigas have a crystal of about 29 MHz, NTSC are 28 MHz. You'll have to change that as well, unless the TV is clever.

tony

[Peggus]

Thanks.
I've already figured out the color problem has to do with the frequency of the color subcarrier.

I found some circuits for RGB to NTSC S-Video converion though so I might try those.

[amigau]

can't you just use NewMode or a similar mode promoter to control the output?  Worst case scenario, you boot the computer to the early startup-screen, pick NTSC and when it gets into WB, then any time you have to run something, have NewMode promote it into NTSC, too, I don't know why that wouldn't work. . .

kevin orme
amiga university
www.amigau.com

[JimS]

You might try one of the old Amiga 520 encoder/modulators on the RGB output.  That's essentially what you'd be building.  

[Rigger]

@Ilwrath

Myself included will always be greatful to Warren for his excellent A4000 FAQ.

[Ilwrath]

@TonyW-
The changes listed should be all the A1200 needs.  As I understand it, the rest of the frequencies are generated by the chipset, so that's why a simple pin on the Alice should do the trick.
Of course, it's far from a simple change, and I still don't know why you wouldn't just USE DEGRADER???  Unlike the early start menu, Degrader will work with almost all games, as it physically tricks the hardware.... I use it to get real PAL mode on an NTSC A1200 all the time.

@Rigger-
Yes, Warren's A3000 and A4000 FAQs help out quite often when I am working on a machine.  They are the best references, by far.

[tonyw]

@McIlwrath
" As I understand it, the rest of the frequencies are generated by the chipset, so that's why a simple pin on the Alice should do the trick."

I'm afraid that you are mistaken. The chipset only divides the system clock by various numbers to derive all its output and internal clocks. So the 7/14 MHz bus clock, the video scan clocks (50 H & 15 k) and the colour subcarrier clock (3.58 / 4.43 MHz) are all derived from the 28 or 29 MHz master oscillator.
Changing the link can alter things like colour subcarrier phase swapping (PAL/NTSC) and division ratio (x8 for NTSC or x6.666 for PAL) but the master clock still needs to be changed slightly to get the right frequency. The chip can't do that.
The same circuitry was used in the C64, C128 and Amiga 1000, albeit integrated into the Agnus chip. I would guess it's the same logic in the A1200. It uses the minimum of hardware to do the job and the chip can also put out the bus clock (which in the C64 and A1000 depended on whether you had a PAL or NTSC crystal).

tony