The S3DPU reset itself again on 8/5/98. As expected from a reset, SWICS
and SWIMS were put into standby mode. SEPICA was turned off via the
spacecraft autonomy shutoff procedure. Other ACE instruments are unaffected.
SEPICA will be restarted on 8/7/98. SWICS and SWIMS HV will be ramped up
again by early next week.

A partial reset occurred earlier in the day. In that case, the command
and command error counters were set to zero, but no other anomalies were
noted. 

Analysis of the reset on June 8 1998 has provided more information about the
state of the S3DPU beforehand, but no conclusive explanation for the
resets has been determined. The memory showed signs of bit errors. These
should have been cleared by a scrubbing routine that was apparently
disabled for an unknown reason.

The autonomy shutoff of SEPICA appears to be a consequence of the S3DPU
restart algorithm, not from a real overcurrent condition. The S3DPU can
create this situation by briefly setting the overcurrent limits of the
SEPICA low voltage supplies to zero. This in turn puts the supplies in a
self-protection mode that is captured by the autonomy shutoff. In the
7/8/98 reset, the SEPICA shutdown occurred at the completion of the
S3DPU restart. 

Data from this S3DPU reset is being processed for further analysis to
determine the cause of the resets.

The only impact of an S3DPU reset is the loss of several days of data from
SEPICA, SWICS and SWIMS. The other six instruments on the ACE spacecraft
are functioning normally.