Section 4 - Troubleshooting; Overview; Updating The Software; Video Failures - Sony KDL-32BX320 Service Training Manual

SECTION 4 - TROUBLESHOOTING

OVERVIEW

Most troubleshooting for this chassis focuses on the 3 major
components used:
• The Main Board (A)
• Power Supply
• LCD Panel
This chapter provides practical troubleshooting procedures based
on the various symptoms that will appear when a particular circuit
fails to operate properly. Typical failure symptoms will be discussed
in this chapater with troubleshooting flowcharts for each symptom in
the Section 5 - Flow Charts and Diagrams on page
NOTE: Always remember to check the Sony Authorized Servicer
Portal at www.sony.com/asp
along with triage charts to quickly identify the most like part to
complete the repair based on the symptom.

UPDATING THE SOFTWARE

As mentioned in Section 2 - Software
several issues that may be resloved by updating the software to the
latest version. For a list of possible correctable issues see
the Software Version on page
KDL-32BX320/32BX321/32BX420/32BX421/40BX420/40BX421/46BX420/46BX421
31.
to access the latest technical bulletins
Requirements, there are
16.

VIDEO FAILURES

Problems that develop in the video circuits can appear as subtle or
major distortions, a loss of one or more colors, improper video level,
or a complete loss of video. When troubleshooting LCD display
devices the problem must be isolated to 2 major components: The
main board where the video processing is performed or the LCD
panel. In some cases the TCON may not be available as a separate
component and replacement of the LCD panel is required to rectify
a TCON problem.
Distortion in the video signal that affects all inputs can be challenging
at times since any of the above mentioned components can be the
cause. Fortunately, each of these components tends to generate
unique symptoms when a problem occurs. Some distortions may
occur that could be caused by either of these components but a
good understanding of the circuits and further investigation will
isolate the suspected circuit. The following sections will cover the
various scenarios of problems that may occur in the video processing
circuits.

NO VIDEO

A "no video" complaint can be caused by a number of reasons. The
first step is to determine if the condition is present from all input
Checking
sources. If any video source is working properly, the TCON (located
within the LCD panel) can be assumed to be OK. The backlights are
also functioning properly. Although it is unusual for a backlight failure
to cause a complete loss of video (the TV will shut down if a backlight
power or open LED is detected) there have been cases where the
backlights have failed to turn on without the unit shutting down.
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