First, I recently started using a new ACA500Plus from Individual Computers. The thing is great. I am posting this for anyone else who may wonder about the PAL/NTSC switching.
I am in the US but the Amiga 500 I'm using the ACA500Plus on previously had an Agnus 8371 AND the crystal on the board is 28.37516 MHZ the board version is 5 . So a PAL machine to start.
With the ACA500Plus, I ordered the 8372A and plugged it in. On the ACA500plus menu, the chip showed up as an ECS NTSC. So I hit the space bar and the size of the image does become slightly decreased in the vertical aspect and a little clearer but the menu on the ACA500Plus still Identifies it as a ECS NTSC chip. Short version, even so, nothing really looked right....I used the ACAPlus Menu to change to PAL, I used the pre menu (hold down both buttons at boot) and switched the setting under prefs on WB 3.1. Maybe it is common knowledge, but with software switch it was always identified as ECS NTSC chip.
I pulled the chip and put tape on pin 41 to prevent contact..its now identified as ECS PAL chip. For anyone else who might wonder about this....even if you hit the space bar, or change prefs in Workbench it is still identifying the chip as ECS PAL. I was approaching it with the idea that the software switching somehow "tricked" it into thinking it was the PAL or the NTCS chip and fixed the clock frequency. It does not appear to do so.
Anyway, this Amiga seems to me to look better with the PAL Agnus (blocked pin 41) than it did with the default Agnus hardware set to NTSC, even when using software to switch to PAL mode. . The monitor is a 1080 going through RGB.
I am a new comer here and to the Amiga. Fell free to educate or correct as needed.