The apollo accelerator cards for the Amiga A1200 are very good cards but on certain revisions of motherboards will refuse to work. The main problem boards are the Rev 1 D.4 and Rev 2B. To make these accelerators work a small modification needs doing to the motherboard. Exactly how involved this will be really depends on your motherboard and the revision of Budgie installed on your motherboard. Budgie is a custom chip which is situated in the middle of your motherboard. Certain advertisers in the Amiga press will offer to so these mods for around thirty UK pounds plus postage but by following the information below at the worst case it will cost you around 6 pence and about 15 minutes of your time to do. The resistors (if required) are readily available from suppliers such as Maplins for just a couple of pence each.
And so to the modifications. Now this is not for the fainthearted.
Revision 1 D.4 motherboard
Make sure you have a revision 1D4 motherboard. And read all the following before starting. Firstly check which revision of the Budgie chip is installed.
Budgie revision 01
If your Budgie chip says budgie rev 01 or Budgie rev 0 CBM xxxxx -01 (where xxxxxx are some other numbers) You are going to have to remove your amiga motherboard completely from the case and on the underside of the motherboard anderneath the Alice chip you will find two surface mount capacitors. they are called E123C, and E125C you need to carefully remove these with a soldering iron. Then put your amiga back together and you are away.
Budgie revision 02
Now then if your Budgie chip says budgie rev 02 or Budgie rev 0 CBM xxxxx -02 (where xxxxxx are some other numbers) then you need to do the modification as revision 01 but also need to do another small mod to your board. Remove XR358 470ohm pull up resistor and add a 470 ohm resistor to pin 43 of Alice (U2).
Revision 2B motherboard
Budgie REV 01 and 02
You are going to have to remove your amiga motherboard completely from the case and on the underside of the motherboard anderneath the Alice chip you will find two surface mount capacitors. they are called E123C, and E125C you need to carefully remove these with a soldering iron. Next add a 470 ohm pull up resistor to pin 43 of Alice (U2). Then change R118 from 470 ohm to 220 ohm. Then put your amiga back together and you are away.
IMPORTANT NOTICE
These hardware mods have been tested and should work on your machine. But you undertake all these mods at your own risk. I will not be held responsible for any damage or loss caused by you following these instructions. If you are at all unsure about these mods have them checked and carried out by a reputable Amiga repairer.