From the Manual so I get it right, although translated through Google.
3.2.5
Agnus - IC52
Agnus is responsible for the control of the chip-RAM, the video sync signals (HSY, CSY, VSY), and contains the coprocessors copper and blitter. Agnus also contains the complete DMA logic for all six possible sources. On this board 2MB Chip RAM is installed, a reduction to 1MB is not possible.
Agnus was produced in many versions, two of which can be used on the A1000 motherboard. The versions 8372B (A3000) and 8375 (A500 +), part number 318069-18 are used (tested).
When using a 8372B Agnus by placement of a resistor R75 and jumper switchover of the start screen between PAL X17 (X17 jumper open) and NTSC (X17 jumper closed) he will follow. If the components are not fitted to the 8372B starts with a PAL screen.
Note: The Agnus 8375 is not for a PAL / NTSC switch designed. When using this block may jumpers X17 and resistor R75 not be loaded. This would result in a malfunction of the Agnus 8375 with picture noise and unstable performance of the A1000 motherboard. For this reason, the components are listed as "not equipped" located in the circuit diagram.