Where is the Best Place to get +5 Volts A1200
 

Hi All,

I have a NTSC Amiga 1200. I am looking at doing the PAL/NTSC mod with pin 41 of the Agnus to a 4.7K resister then to +5 Volts. Where is the best place on the Amiga 1200 mother on getting the +5 Volts?

Thanks for any help.

The easiest place to take it from is at the rear of the power in socket. Just solder a wire to the correct pin at the back of the socket. If you look at this guide (http://www.stone-oakvalley-studios.c...g/?page_id=126), it shows you where the 5 volt pin is. (Scroll down the page to get the relevant picture).

depend on your soldering skills but as a principle as close to Agnus as possible - best somewhere from Agnus pins (pin 52 for example).

ptyerman: Thank you. I'll use that on another item I am working on.

pandy71: Intersting. So, I could do everything at the chip.

1) pull Alice's pin 41 off the motherboard
2) Get a 4.7K Ohm resister and solder that to pin 41 (/NTSC).
3) The other side of the resister, solder to pin 52 (Vcc2).

If I wanted to put a switch in. I would put solder pin 41 (/NTSC) to the middle of the switch. On one side solder the resister that leads to pin 52 (Vcc2). On the other side solder pin 42 (GND2).

Just making sure this about covers it before I attempt it. Everything I said seems correct to you?

Sounds ok but im not sure what is difference between PAL and NTSC A1200 board - if you check A1200 schematics then NTSC Alice pin is pulled up by resistor R202 on board and grounded on pad R203 - perhaps this can be used - are you able to locate those components on PCB and do photo?
I assume that NTSC version of PCB can have some components not populated but layout is same as in PAL version - like R202 not present, R203 grounded...

Btw.
PAL/NTSC will not provide full PAL compatibility - for this also main system clock need to be switched - i assume with NTSC clock system will be kind of hybrid, only vertical framerate will be PAL like (50/25Hz)but remain part will be NTSC (H Sync for example).

Thanks for the information, pandy71. The main issue I have is the picture is down on the screen when playing a lot of games. I want to bring the picture up on the screen. I was told doing this mod could accomplish this. Basically, playing PAL games on a NTSC system. Also, the demos I like seem to do this as well. My Workbench in NTSC, however, fits on the screen perfect. I'll let you know how it works.

Games like Aladdin and Hook. The lines are off the screen so even if I move the picture up on the monitor, there are no more lines to move up. All I got is black screen.

I don't recommend soldering directly to QFP pins unless absolutely necessary. I'm sure you can find these signals at a more suitable location elsewhere on the board.