JBL A6000GTi, Service Manual, Page: 20 / 62

137159-1 Rev. 1 A6000GTi Service Manual

2003 Crown Audio, Inc.
Maintenance 4-1
4. Maintenance
4.1. Where to Begin
Effective repair involves three basic steps:
1) Determine the symptom(s) of the problem
2) Identify the cause(s) of the symptom(s)
3) Repair the unit to eliminate the cause(s)
To determine the symptoms, you will want to get as much information from the user as
possible. Get as much information as you can about the system and how the amplifier is
used. There is always the possibility that the problem will show up only if used in a
specific way.
Once you have all the information about the symptom(s), it is time to inspect the amplifier.
A careful visual inspection is valuable for most problems, which you may encounter. To
inspect the inside of the amplifier remove the cover as described in Section 4.3.1.
Begin the inspection by looking for anything abnormal, like loose connectors, broken wires
and burnt or visibly damaged components. Inspect the printed circuit assemblies for
broken traces and loose connections. Be thorough. The time you spend visually
inspecting the amp is time well spent.
4.2. Surface Mount Technology
The A6000GTi amplifier uses surface mount technology in its design. There are several
advantages to using surface mount technology (SMT), including; (1) surface mount
devices (SMDs) are much smaller, and are mounted to the surface of the board, so more
components can be placed on the board. (2) Components can be attached to both sides
of the board, allowing the board size to be reduced. (3) SMT boards are lighter and
provide better electrical performance and signal speed.
Of course, there are also things to watch out for with SMT. (1) The placement of the
components on the board, not through a hole, makes the components and solder joint
more susceptible to damage. (2) Rework of SMDs can often require specialized tools,
equipment, or training. (3) SMDs are very small and can be difficult to handle, see, and
identify.
Remember that on some of the boards, the SMDs are GLUED to the bottom of the board.
This is done for manufacturing purposes. Take care not to damage components while
trying to remove them from the surface of the module.