Template:ACA Board Modifications
possible required board modifications
A1200 board, solderside overview
four capacitor places circled
Commodore and Escom have made all kinds of mistakes when assembling A1200 motherboards. Internal memos from Commodore are available that clearly say to remove capacitors E123C and E125C for any version of the Budgie chip, yet, you can find lots of boards out there that have these capacitors assembled. Less often, but at least as severe, some boards have capacitors E121C and E122C assembled. This will harm the quality of the 14MHz board clock to a degree where most accelerators (not just ours!) become instable.
You cannot tell from the board revision or the year of your board if the capacitors have been assembled, as practically all revisions have been assembled with all combinations of chipsets and timing fixes (required or not). Your only chance is to check your individual board and remove the capacitors if they are there. There is no reason for these parts to be assembled, other than some Commodore employee's excuse about not getting the memo.
Only our latest accelerators ACA1233n, ACA1221ec and ACA1221lc have implemented special logic that can handle most of the timing errors caused by wrong assembly of the A1200 main board. These cards may work reliably, although the mentioned capacitors are installed. We still recommend to remove the capacitors, as they have other negative effects, too.
