With some Falcons (mostly main board revision C/D) problems
with the DMA system can (not necessarily) arise. This can be
noticed as SCSI and sound problems.

The following solution for the problem should work:

- Without FPU:
  There is a wire from the upper connection of R221 to the
  clockpatch-IC 74F04 or 74F08. Remove this wire from the IC
  and solder it to the upper connection of R217 (same point where
  the yellow wire of FX is connected!) Result should be a connection
  between R221/upper pad to R217/lower pad.

- With FPU:
  Here a wire leads from 74F04/74F08 directly to the DMA chip.
  Remove this from the 74F04/08 and connect it to the upper pad
  of R217 (where also the yellow wire is connected). Result should
  be a connection between R217/upper pad and DMA chip.

Should the problems remain (especially with 40MHz CPU clock) the following
change could help:
- Re-establish the connection R221/upper to 74F04/08 or DMA-chip to 74F04/08.
  (i.e. remove the patch we just recommended :-) )

- With/without FPU:
  There is a wire from the LOWER connection of R221 to 74F04/08. Remove
  this wire from R221 and solder it to the upper connection of R217.
  (yellow wire)

For the interested:
All these modifications are changing the timing of the DMA chip's clock. This
is the most crucial part of the Falcon design, so changing the Falcons timing
(as accelerators do) creates problems mostly at this part...

Georg Acher / BlowUP               11.08.95

