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Training Manual
KP-60WE610
LA-2 Chassis
Models: KP-42WE610
KP-50WE610 VPL-HS20
KP-60WE610
KFD-60XBR950
KFD-70XBR950
VPL-HS20
Diagnostics and Troubleshooting
Course: TVP-17
Table of Contents
Introduction ...........................................1 6. The VPL-HS20 .................................32
1. The LA-2 Chassis ............................2 Overview ................................................................ 32
Overview ................................................................. 2 Overall Block diagram .......................................... 32
Circuit Layout ......................................................... 3 7. Power Supply ..................................35
Circuit Board Locations ........................................ 6 Overview ................................................................ 35
2. LA-2 Power Supplies .......................7 Theory of Operation .............................................. 35
Overview ................................................................. 7 Power Supply Troubleshooting ............................ 39
Troubleshooting ..................................................... 10 8. Protect Circuits ...............................41
3. LA-2 Protect & Self-Diagnostics ..12 Overview ................................................................ 41
Overview ................................................................ 12 9. Video Circuits ..................................45
Direct Relay Deactivation Protection ................. 12 Video Input Selection ........................................... 45
Protection and Self-Diagnostics ......................... 14 B Board Video Processing ................................. 47
Entering Diagnostics Mode ................................. 16 C Board Video Processing ................................. 48
4. LA-2 Video Processing ..................17 Troubleshooting ..................................................... 49
Overview ................................................................ 17 10. Servicing the VPL-HS20 ..............53
Video Input & Switching ....................................... 17 Overview ................................................................ 53
Video Processing ................................................. 19 Disassembly .......................................................... 54
Troubleshooting ..................................................... 22 Servicing the Prism Block .................................... 56
Internal Pattern Generator .................................... 27 Service Mode ........................................................ 60
5. LA-2 Audio Processing ..................30 Additional Service Tips ........................................ 61
Overview ................................................................ 30
Circuit Description ................................................ 30
TVP-17 - Introduction
TVP-17 - Introduction
The last several years have seen dramatic growth in the number of display products utilizing Liquid Crystal
Display devices for both direct and projection-type televisions for motion video viewing. In a market long dominated
by the cathode-ray tube, LCD technology has slowly overcome the inherent flaws of this display device, particularly
geometric distortion. LCD technology has been around for over three decades; however, certain limitations
prevented it from immediately replacing the CRT displays. Although other technologies exist such as Plasma
and DLP, their costs remain relatively high. LCD provides for a middle ground and is currently the best display
format for the price.
One of the limitations slowing LCD technology for use in motion picture display was its extreme lack of contrast
compared to the CRT. Original liquid-crystal designs used a scan pulse to select a particular pixel and a variable
voltage to change the amount of "twist" in the crystals to vary the amount of light passing through, usually from
a backlight source. Capacitors across these terminals would slow the rise time of the control voltage. Cross-talk
among pixels also contributed to unacceptable contrast levels for television viewing since each horizontal line of
pixels is selected, causing the charge among the capacitors to leak across the rows. This is known as "Passive
Matrix".
By adding thin-film transistors (TFT), greater control can be achieved at each pixel and a dramatic increase in
contrast and resolution is seen. Earlier versions of TFT displays were still quite a ways off from the contrast ratio
achieved by CRTs and struggled to generate contrast ratios exceeding 600:1. Newer design LCD panels have
more than doubled this ratio to 1600:1 and, although still below CRT, DLP and plasma levels, the picture quality
of the newest generation of LCD projection televisions has risen to a level that rivals these other technologies.
This has generated a dramatic rise in sales of LCD-driven televisions.
The purpose of this manual is to introduce Sony's newest models of front and rear projection display products.
Five new Grand Wega