Read JBL ON TOUR XT (serv.man5) EMC - CB Certificate online
12/05/2006
Report Number: 3109671ATL-005
Issued:
Intertek
Measurement of immunity to eletrostatic discharge (EN 55020 - Sec. 5.9)
8.0
Method:
When one or several metallic accessible parts are subject to the ESD test, the charge shall be removed from the point where the ESD pulse is to be applied,
as no guarantee can be given about the resistance between this and other accessible points on the product.
as no guarantee can be given about the resistance between this and other accessible points on the product.
A cable with 470 k-Ohm bleeder resistors, similar to the one used with the horizontal and vertical coupling planes, shall be used.
As the capacitance between EUT and HCP (tabletop) and between EUT and GRP (floor-standing) is determined by the size of the EUT, the cable with
bleeder resistors may remain installed during the ESD test when functionally allowed. In the discharge cable, one resistor shall be connected as close as
possible, preferably less than 20 mm from the EUT test point. The second resistor shall be connected near the end of the cable attached to the HCP for
tabletop equipment (see Figure 8), or GRP for floor-standing equipment.
bleeder resistors may remain installed during the ESD test when functionally allowed. In the discharge cable, one resistor shall be connected as close as
possible, preferably less than 20 mm from the EUT test point. The second resistor shall be connected near the end of the cable attached to the HCP for
tabletop equipment (see Figure 8), or GRP for floor-standing equipment.
The presence of the cable with the bleeder resistors can influence the test results of some equipment. In case of dispute, a test with the cable disconnected
during the ESD pulse takes precedence over the test with the cable installed during the test, provided that the charge has sufficiently decayed between the
successive discharges.
during the ESD pulse takes precedence over the test with the cable installed during the test, provided that the charge has sufficiently decayed between the
successive discharges.
As an alternative, the following options can be used:
- the time interval between successive discharges shall be extended to the time necessary to allow natural decay of the charge from the EUT;
- a carbon fibre brush with bleeder resistors (for example, 2 x 470 k-Ohm) in the grounding cable;
- an air-ionizer to speed-up the "natural" discharging process of the EUT to its environment. The ionizer shall be turned off when applying an air-discharge
test. The use of any alternative method shall be reported in the test report. NOTE In case of dispute concerning the charge decay, the charge on the EUT
can be monitored by a non-contacting electric field meter. When the charge has decayed below 10 % of the initial value, the EUT is considered to be
discharged.
- the time interval between successive discharges shall be extended to the time necessary to allow natural decay of the charge from the EUT;
- a carbon fibre brush with bleeder resistors (for example, 2 x 470 k-Ohm) in the grounding cable;
- an air-ionizer to speed-up the "natural" discharging process of the EUT to its environment. The ionizer shall be turned off when applying an air-discharge
test. The use of any alternative method shall be reported in the test report. NOTE In case of dispute concerning the charge decay, the charge on the EUT
can be monitored by a non-contacting electric field meter. When the charge has decayed below 10 % of the initial value, the EUT is considered to be
discharged.
The tip of the ESD generator shall be held normal (perpendicular) to the surface of the EUT.
Tabletop equipment: For tabletop equipment, the EUT is placed on the horizontal coupling plane on top of the insulating foil (0,5 mm thick). When a metallic
accessible part, to which the ESD pulse is to be applied, is available on the EUT, this part shall be connected to the HCP via the cable with bleeder resistors.
accessible part, to which the ESD pulse is to be applied, is available on the EUT, this part shall be connected to the HCP via the cable with bleeder resistors.
Floor-standing equipment: Floor-standing equipment without any metallic connection to the ground reference plane shall be installed similarly to 7.1.2 and
Figure 6 of EN 61000-4-2. A cable with bleeder resistors shall be used between the metallic accessible part, to which the ESD pulse is to be applied, and
the ground reference plane (GRP).
Figure 6 of EN 61000-4-2. A cable with bleeder resistors shall be used between the metallic accessible part, to which the ESD pulse is to be applied, and
the ground reference plane (GRP).
EXECUTION OF TESTS
The testing shall be performed by direct and indirect application of discharges to the EUT as appropriate.
The testing shall be performed by direct and indirect application of discharges to the EUT as appropriate.
Direct application of discharges to the EUT:
The static electricity discharges shall be applied only to those points and surfaces of the EUT which are accessible to persons during normal use. The
following exclusions apply (i.e. discharges are not applied to those items):
a) those points and surfaces which are only accessible under maintenance. In this case, special ESD mitigation procedures shall be given in the
accompanying documentation;
b) those points and surfaces which are only accessible under service by the (end-)user. Examples of these rarely accessed points are as follows: battery
contacts while changing batteries, a cassette in a telephone answering machine, etc.;
c) those points and surfaces of equipment which are no longer accessible after fixed installation or after following the instructions for use, for example, the
bottom and/or wall-side of equipment or areas behind fitted connectors;
d) the contacts of coaxial and multi-pin connectors which are provided with a metallic connector shell. In this case, contact discharges shall only be applied
to the metallic shell of that connector. Contacts within a non-conductive (for example, plastic) connector and which are accessible shall be tested by the air-
discharge test only. This test shall be carried out by using the rounded tip finger on the ESD generator.
e) those contacts of connectors or other accessible parts that are ESD sensitive because of functional reasons and are provided with an ESD warning label,
for example, r.f. inputs from measurement, receiving or other communication functions. Rationale: Many connector ports are designed to handle high-
frequency information, either analogue or digital, and therefore cannot be provided with sufficient overvoltage protection devices. In the case of
analogue signals, bandpass filters may be a solution. Overvoltage protecting diodes have too much stray capacitance to be useful at the frequencies at
which the EUT is designed to operate.
The static electricity discharges shall be applied only to those points and surfaces of the EUT which are accessible to persons during normal use. The
following exclusions apply (i.e. discharges are not applied to those items):
a) those points and surfaces which are only accessible under maintenance. In this case, special ESD mitigation procedures shall be given in the
accompanying documentation;
b) those points and surfaces which are only accessible under service by the (end-)user. Examples of these rarely accessed points are as follows: battery
contacts while changing batteries, a cassette in a telephone answering machine, etc.;
c) those points and surfaces of equipment which are no longer accessible after fixed installation or after following the instructions for use, for example, the
bottom and/or wall-side of equipment or areas behind fitted connectors;
d) the contacts of coaxial and multi-pin connectors which are provided with a metallic connector shell. In this case, contact discharges shall only be applied
to the metallic shell of that connector. Contacts within a non-conductive (for example, plastic) connector and which are accessible shall be tested by the air-
discharge test only. This test shall be carried out by using the rounded tip finger on the ESD generator.
e) those contacts of connectors or other accessible parts that are ESD sensitive because of functional reasons and are provided with an ESD warning label,
for example, r.f. inputs from measurement, receiving or other communication functions. Rationale: Many connector ports are designed to handle high-
frequency information, either analogue or digital, and therefore cannot be provided with sufficient overvoltage protection devices. In the case of
analogue signals, bandpass filters may be a solution. Overvoltage protecting diodes have too much stray capacitance to be useful at the frequencies at
which the EUT is designed to operate.
The test voltage shall be increased from the minimum to the selected test level, in order to determine any threshold of failure. The final test level should not
exceed the product specification value in order to avoid damage to the equipment.
exceed the product specification value in order to avoid damage to the equipment.
The test shall be performed with single discharges. On preselected points at least ten single discharges (in the most sensitive polarity) shall be applied.
For the time interval between successive single discharges an initial value of 1 s is recommended. Longer intervals may be necessary to determine whether
a system failure has occurred. NOTE The points to which the discharges should be applied may be selected by means of an exploration carried out at a
repetition rate of 20 discharges per second, or more.
a system failure has occurred. NOTE The points to which the discharges should be applied may be selected by means of an exploration carried out at a
repetition rate of 20 discharges per second, or more.
The ESD generator shall be held perpendicular to the surface to which the discharge is applied.
The discharge return cable of the generator shall be kept at a distance of at least 0.2 m from the EUT whilst the discharge is being applied.
In the case of contact discharges, the tip of the discharge electrode shall touch the EUT, before the discharge switch is operated.
In the case of painted surfaces covering a conducting substrate, the following procedure shall be adopted:
If the coating is not declared to be an insulating coating by the equipment manufacturer, then the pointed tip of the generator shall penetrate the coating so
as to make contact with the conducting substrate. Coating declared as insulating by the manufacturer shall only be submitted to the air discharge. The
contact discharge test shall not be applied to such surfaces.
If the coating is not declared to be an insulating coating by the equipment manufacturer, then the pointed tip of the generator shall penetrate the coating so
as to make contact with the conducting substrate. Coating declared as insulating by the manufacturer shall only be submitted to the air discharge. The
contact discharge test shall not be applied to such surfaces.
Page 22 of 27
EMC Report for Harman Consumer Group on the JBL On Tour II
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