JMM-5000 User Manual Rev B.01
Page 3
1. IMPORTANT SAFE HANDLING INFORMATION
WARNING!
ESD-Sensitive Electronic Equipment
Observe ESD-safe handling procedures when working with this product.
Always use this product in a properly grounded work area and wear
appropriate ESD-preventive clothing and/or accessories.
Always store this product in ESD-protective packaging when not in use.
Safe Handling Precautions
The board contains a high density connector with many connections to sensitive electronic components. This
creates many opportunities for accidental damage during handling, installation and connection to other equipment.
The list here describes common causes of failure found on boards returned to Diamond Systems for repair. This
information is provided as a source of advice to help you prevent
damaging your Diamond (or any vendor’s) boards.
ESD damage
– This type of damage is usually almost impossible to detect, because there is no visual sign of
failure or damage. The symptom is that the board eventually simply stops working, because some component
becomes defective. Usually the failure can be identified and the chip can be replaced. To prevent ESD damage,
always follow proper ESD-prevention practices when handling computer boards.
Damage during handling or storage
– On some boards we have noticed physical damage from mishandling. A
common observation is that a screwdriver slipped while installing the board, causing a gouge in the PCB surface
and cutting signal traces or damaging components.
Another common observation is damaged board corners, indicating the board was dropped. This may or may not
cause damage to the circuitry, depending on what is near the corner. Most of our boards are designed with at least
25 mils clearance between the board edge and any component pad, and ground / power planes are at least 20
mils from the edge to avoid possible shorting from this type of damage. However these design rules are not
sufficient to prevent damage in all situations.
A third cause of failure is when a metal screwdriver tip slips, or a screw drops onto the board while it is powered
on, causing a short between a power pin and a signal pin on a component. This can cause overvoltage / power
supply problems described below. To avoid this type of failure, only perform assembly operations when the system
is powered off.
Sometimes boards are stored in racks with slots that grip the edge of the board. This is a common practice for
board manufacturers. However our boards are generally very dense, and if the board has components very close
to the board edge, they can be damaged or even knocked off the board when the board tilts back in the rack.
Diamond recommends that all our boards be stored only in individual ESD-safe packaging. If multiple boards are
stored together, they should be contained in bins with dividers between boards. Do not pile boards on top of each
other or cram too many boards into a small location. This can cause damage to connector pins or fragile
components.
Power supply wired backwards
– Our power supplies and boards are not designed to withstand a reverse power
supply connection. This will destroy each IC that is connected to the power supply (i.e. almost all ICs). In this case
the board will most likely will be unrepairable and must be replaced. A chip destroyed by reverse power or by
excessive power will often have a visible hole on the top or show some deformation on the top surface due to
vaporization inside the package.
Check twice before applying power!
Overvoltage on analog input
– If a voltage applied to an analog input exceeds the design specification of the
board, the input multiplexor and/or parts behind it can be damaged. Most of our boards will withstand an erroneous
connection of up to
36V on the analog inputs, even when the board is powered off, but not all boards, and not in
all conditions.
Overvoltage on analog output
– If an analog output is accidentally connected to another output signal or a power
supply voltage, the output can be damaged. On most of our boards, a short circuit to ground on an analog output
will not cause trouble.
Overvoltage on digital I/O line
– If a Digital I/O is connected to a voltage above the maximum specified voltage,
the digital circuitry can be damaged. On most of our boards the acceptable range of voltages connected to digital
I/O signals is 0-5V, and they can withstand about 0.5V beyond that (-0.5 to 5.5V) before being damaged. However
logic signals at 12V and even 24V are common, and if one of these is connected to a 5V logic chip, the chip will
be damaged, and the damage could even extend past that chip to others in the circuit.