Installation and test Procedures for the ST/DT series monitor and tester  1. Connect the ST/DT tester ground wire to an existing common point ground
2A. ST (single
threshold) series wrist strap test: Insert the male banana plug
from the tester/calibrator (marked wrist strap) into the female
wrist strap input of the ST ESD monitor. The Operator LED
should turn red. Pressing the High Operator button should cause the
LED to turn green . The low button is not part of this test.
2B. DT (dual
threshold) series wrist strap test: Insert the male banana plug
from the tester/calibrator (marked wrist strap) into the female
wrist strap input of the DT ESD Monitor. The Operator high LED
should indicate red and the operator low LED should indicate green.
Pressing the high or operator buttons should cause the high LED to
turn green. Pressing the low button should cause the low LED to turn
yellow.
3. ST and DT
Bench Mat Test: Insert the male 1/16" mini-phone style
plug from the tester/calibrator (marked mat) into the ST or DT
monitor bench jack. The audio alarm should sound. Press the
bench button. The bench LED should turn green and the audio alarm
should no longer sound.
The ST and DT series
continuous ESD monitors are an improved design over our AEI-92xx
series monitors. The new DT and ST circuitry provides increase
shielding and resistance to operator movement for a reduction in
false alarms. The ST series monitor is a single threshold monitor
(like our original 92xx). This style monitor detects when the
wrist strap is above the high resistance threshold or above the body
capacitance specification. The DT series monitor provides
detection when the wrist strap is above the high resistance
threshold or above the body capacitance specification AND when the
wrist strap is below the low resistance threshold.
ESD 20.20 describes the
requirements for the ground path resistance for a wrist strap
system. The 1999 standard was 10 Megohms or less and the 2007
standard is 35 Megohms. We do not test for this resistance, we
provide this path to ground thru our monitors. The AEI series
monitors have a resistance to ground thru the operator input of
around 250 K ohms. This resistance combines with the maximum wrist
strap resistance of 1.2 Megohms resulting in a ground path
resistance less than either of the ESD 20.20 standards.
Our monitors put out a minute
AC signal used to detect the body capacitance of a person who is
wearing the wrist strap. Because this signal will interfere
with an ohmmeter reading the operator ground path resistance thru
our monitors must be measured with the power off. Connect one
lead of the ohmmeter to the operator input and the other lead to the
ground connection on the power supply plug. Measurements
should be 260 K ohms plus or minus a few percent.
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