Suggested frequency of service:
1. End of August (two-weeks after Bill Lutter leaves), 2. End of September
3. End of October.

Suggested Steps for servicing:
ALWAYS DO THE LEAST AMOUNT OF SERVICING REQUIRED (Least is service check,
Most is trouble shooting).
1. Service check: Steps 1-6 only (no disk swap, no problems, instrument
never stopped).

2. Disk Swap/Tape Dump  Service: Steps 1-8, 10, 12-15
In particular, don't do step #9 (SYS-INIT) or Step 11 (Reprogram).
SWAP DISK AND NOTIFY UNIV. of WISCONSIN, WHEN DISK OVER 350 MBYTES.
SERVICE SHEET STEP 6 GIVES YOU THE DISK USAGE IN KBYTES.

3. Trouble-shooting: Contact UW first and discuss problem.  Usually
the trouble shooting involves power/equipment problems.  Do all
steps including sys-init and reprogramming. 


Service Equipment Maintenance:
1. Charge EHT the night before and after each service run.  Additionally
charge once a week.  If EHT loses memory due to low power, then
consult PASSCAL manual/UW  on resetting EHT. 
2. Charge RefTek battery (used to power nanometrics clock) before
each service run.
3. Always check time against dual time wrist watch set in morning
to GMT at HVO.
4. Check voltmeter and change batteries if necessary prior to service run.
5.  As a courtesy, notify contact person for each site  of intended
service visit.  
6. Bring spare fully charged 12 V battery.

Problem/solution

EHT/connection to DAS Problem:
a) if (UTILITIES-VERSION#) fails, this is usually diagnostic
of a bad EHT connection.  Check for bent pins on cable connection to EHT.
If pins bent, switch to different cable and request from UW a replacement cable.

Bad power:  a) swap battery  b) check battery
with load 50-ohm resistor in parallel to battery posts, c) reconnect power to to DAS,
d) do all service sheet steps EXCEPT STEP #8 (SWAP DISK) AND
STEP #10 (ERASE DISK).

Timing probably never an issue. In worst case scenario, set wrist watch
to HVO time, and RefTek time  to nearest second. IF DAS time 
significantly off (off by more than a few seconds) NOTIFY UNIV. OF WISCONSIN.

Equipment problems as diagnosed by:
Can't spin disk or Das State other than START-ON:
a) check power b) do a sys reset and try again,
c) do a sys -init, try again, do all service sheet steps EXCEPT FOR STEP #8
(SWAP DISK) STEP #10 (ERASE DISK).
d) swap out the disk and try a different disk.  Do all service steps
because you will be swapping out the old disk, erasing the new disk,
and reprogramming.  Old disk will require special care to retrieve
data (probably relabelling) so label disk and indicate problem.

Sensor problems:
Sensor unlevelled: relevel and note direction out of level on field sheet

Sensor not oriented to wall:   note approximate direction of north/east 
(may be difficult with compass inside building) and reorient north/east
with wall directions closest to north/east based on compass orientation
to edges of  building done outside of building.

Monitor tests:
a) background noise should be greater than 10 counts.  
If not, Is sensor connected to RefTek?

b) dominant frequency of L-4 sensors is around 1-hz.  Check for
both low frequency and high frequency background noise.
All high frequency noise diagnostic of unlevelled sensor, or
bad component.

c)Tap test (tap on RefTek case) or (1-hz) knee-bend
should be recorded on monitor.  If not, is sensor connected?
Signal should also have high and low frequency in it.  If not,
may be diagnostic of problem sensor.  NOTIFY UNIV. of WISCONSIN.
Have correct parameters been sent to RefTek?  Is acquisition
stop off? (You can't monitor in acquisition  start-on state).

NOTE: EHT programmed to display 16-bit data, but A-08 ch 4-6 is 32-bit data.
So, counts < +/- 32K unaffected by display. Higher counts can look very funky.

   Send email to UW (clifft@geology.wisc.edu and/or wlutter@geology.wisc.edu)
after a service run indicating whether site was running ok or if site
required a disk swap. Anything more complicated than this should be
discussed with UW prior to further servicing.