Fat Agnus 8372A comes up as NTSC chip, how to change to PAL

[77slevin]

Hi all,


Like I recently asked I finally found a FAT AGNUS 8372A for my Rev 5 Amiga 500 motherboard to take advantage of the 1MB chip ram in corporation with my trapdoor expansion from amigastore.eu. The thing is: booting up gives me NTSC screenmodes until I reach Workbench (amigaOS) and then starting Sysinfo flips again to NTSC on an otherwise PAL board and PAL JVC PVM.



I reached out to the seller to ask if I could swap the chip for a PAL one, because the ad did not mention this was NTSC and I got a a snooty reply back that the issue was not the chip but the board and Jens does not have to mention this on the sales page, because when I'm able to swap chips I also must be able to find the relevant solution on a well documented computer. Well excuse me princess, but it has been 35 years, I'm absolutely not up to date with every tip and trick about the Amiga. I searched but haven't found a howto or usable instructions yet.



So the solution should be solder points / Jumpers on the board to force PAL mode. Anybody on here knows what he is on about and can give this old timer some tips?


To add: When I press and hold 2 mouse buttons at boot up (Amiga 2 finger salute) I can switch to PAL with the space bar, the Amiga boots AmigaOS but yet again fails to display SysInfo in PAL mode.

Screenshot of ShowConfig: https://i.imgur.com/QRYH71T.jpg

[lesta_smsc]

May not be relevant but just wondering whether Sysinfo may be set to boot certain screenmode? Eg like how you can set settings on WHDLoad in the info section?

[77slevin]

I dont think so: before replacing the FAT AGNUS, everything showed up in the correct PAL modes for my territory, now every game I start with WHDLOAD gives me a rolling picture on my monochrome output, making it unusable.

[r.cade]

The 8372A is not NTSC or PAL, it is both, switchable. It is NTSC if pin 41 is grounded, and PAL if it is not.

If you have an official PAL board, I am not sure why it would set to NTSC (pin 41 grounded).

I don't think there is any jumper on a Rev5 board, so you will have to track down what trace goes to that pin and cut it on the board, or track down what is connecting it to ground and pull that out (probably a resistor somewhere- I would have to look at the schematics).

[gurth]

I put a small piece of tape on pin 41 when I fitted mine. Did the job.

[77slevin]

Thanks, your reply lead me to this post: https://www.lemonamiga.com/forum/viewtopic.php?t=15016. Poster taped of pin 41 and all was well. Now I have something concrete to hunt down

[77slevin]

Found this great image on Google to illustrate what needs to be done : https://i.imgur.com/m3uREWy.jpg. For future Amigans in my situation.

[77slevin]

It worked flawlessly. Thanks everyone who chimed in. Happy camper over here.