TB-6511
Page 2 of 4
DESCO EMIT WEST
- 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
DESCO EMIT EAST
- 90 Hudson Road, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Web Site: http://www.descoemit.com
Wrist Strap Test:
When power is supplied to the 50513, the “STRAP”
indicator will illuminate red until a functional single wire wrist
strap is worn and plugged into the “WRIST STRAP
MONITOR” jack. Plug a single wire wrist strap into the
connector marked “WRIST STRAP OPERATOR” place the
strap securely around either wrist. the “STRAP” indication
will be green if the total capacitance of operator and wrist
strap is above approximately 50 picofarads and the series
resistance of the wrist strap cord is less than approximately
2 megohms. Should the capacitance or resistance change
above or below these thresholds, the “STRAP” indication
will illuminate red and the alarm will sound for
approximately 3 seconds.
A wrist strap, plugged into the “WRIST STRAP/GUEST”
banana jack, is connected directly to earth ground and is
not continuously monitored.
Because of the inherent nature of single-wire wrist strap
monitoring based on the body capacitance principle, it may
sometimes be necessary to adjust an individual unit to a
particular operator’s body capacitance. Adjust the unit by
removing the top cover of the unit and turning calibration
potentiometer R7 until the “STRAP” indicator just turns red
while the operator is wearing the wrist strap. Then, slowly
turn the potentiometer in the opposite direction until the
“STRAP” indicator just returns to green. Verify that
removing the wrist strap will cause the indicator to turn red
and that the alarm sounds for approximately 3 seconds.
Worksurface Test:
Wear a plugged-in wrist strap to produce a “PASS”
condition for all circuits (all green LEDs are on). Disconnect
the worksurface wire at the rear of the 50513 or at the
bench surface. Observe that the “BENCH” red LED turns
on the the audible alarm is activated for approximately 3
seconds. Reset the alarm circuit by reconnecting the
worksurface wire to the 50513. The green “BENCH” LED
remains on, indicating a bench top OK condition when the
resistance between the worksurface to ground connection
and the worksurface measurement connection from the
50513 is less than 50 megohms.
NOTE:
Special order 50513 units may have special factory
set bench top trip-points and may also include the optional
STANDBY switch. Specially ordered 50513 units may also
be factory set for continuous alarm. The volume of the
audible alarm may be adjusted with potentiometer R37.
Figure 2. Item 50513 Hookup
© 2004 DESCO INDUSTRIES INC.
Employee Owned
