Video Distortion; Additional Troubleshooting Information - Sony VAIO PCG-V505 Series Training Manual

SERVICE TIP: The high voltage ballast circuit used to fire the fluorescent lamp generates several thousand volts
of electricity. It is too high for most voltmeters to read and is usually loaded by the meter. Holding an oscilloscope
probe near the ballast is an effective and safe way to test it. Set the scope gain to high (50mv) and the sweep
to around 20us. If the ballast is operating you will be able to see the high voltage pulses on the scope screen. If
pulses are present, the lamp is defective.

Video Distortion

Distortion problems in LCD-type displays generally appear in three forms:
• Distinctive horizontal or vertical lines (lit or unlit).
• Overall distortion affecting the entire screen
• Localized distortion
Fixed Horizontal or Vertical Lines:
The digital information sent to the panel from the video driver is supplied with a cable containing several dozen
lines. The display panel contains several thousand lines intersecting along a horizontal and vertical plane to
control each red, green, and blue pixel. The cable feeding the data to the panel contains serial data information.
Once received by the panel processing drivers, the serial data is de-multiplexed by shift registers to active
several dozens of lines at the panel. If one line is fully lit or missing, the failure definitely lies within the LCD panel
and it must be replaced.
Overall Distortion:
This can appear as a loss of a primary color, loss of detail, or pixilated distortion. It is unusual for the pane itself to
cause this. The video driver circuits are at fault and can be further verified by viewing with an external monitor.
Localized Distortion:
Usually appears as color "blotches" on the screen. This is a defective area on the panel. It can be caused by a
defect in manufacturing or damage due to abuse. If caused by abuse, there is usually evidence of damage to
the screen face cover.

Additional Troubleshooting Information

A knowledge base is maintained on the Sony ESI Website (http://service.sel.sony.com/) to provide up to date
information on tips and service bulletins. The model you are servicing should always be looked up to view any
possible sources to assist in repairing the unit. Below are some issues pertaining to the PCG-V505DX:
• E23082588
• E24252134
• E24447103
• E24728959
E24742567
•
Notebook PC motherboard Part Number
Erratic Touch-Pad
Missing Hidden Recovery Partition
PC Card isn't recognized
Notebook PC Recovery Media Part Numbers
1. PCG-V505 Series Troubleshooting
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