Watchdog - Teledyne MD300 Operating/Service Instructions Manual

Service Manual
Symptom
Cannot adjust
calibration or alarm
settings
Note: In the event that none of these procedures produce desired
results, remove the batteries and return the unit to Teledyne for
repair.

3.7 Watchdog

The AD300/MD300 is equipped with a watchdog circuit that
continuously monitors the electronics for proper operation. If the watchdog
detects a failure, one of the following codes will appear on the LCD.
The error codes can appear on the LCD when batteries are first
installed, during normal operation or if the unit is subjected to extreme
shock. In some cases an additional digit is used in the error code to
supply additional information. For example, the error code 6 and 7 are
followed by another digit listed as (N) in Table 3.2. The error code 65
would indicate that a key is stuck and this key is the Silence key.
In addition to supplying visual error codes, the audio device will
beep a number of times to indicate the general error in case the display is
not functional.
NOTE: To reset the watchdog error code. Remove one battery for
5 seconds and replace. If the error persists contact your
locale representative or Teledyne for assistance.
Why
Critical settings require
two keys be pressed in a
specific order.
LOCK/UNLOCK key is
active
Teledyne Analytical Instruments
AD300/MD300
What To Do
A) If display is not
flashing press lock
key once to activate
keys. Press desired
function followed by
the Up and Down
key.
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