VPL HS20 _ DISASSEMBLE PROCEDURE _ PRISM BLOCK SERVICE _ SERVICE MODE ENTRY & EXIT _ LAMP TIMER RESET
The only device on the VPL-HS20 with
a specified service life is the lamp. It is easily accessed through the lamp cover
door and can be replaced by the customer. The circuit boards are stacked
together and joined by board-to board hard connectors or conventional or flat
wire cables. If access to the boards is required, an extender kit (PN A-1606-452-A)
is needed. The kit has a large number of extender boards and cables. Since the
unit is considered board
level repair, this kit should not be needed in most cases.
CIRCUIT BOARD EXTENDER KIT
Click on image.
Right click on the enlarged image, save image as, to a folder (My
document > My Pictures).
DISASSEMBLY
Six screws are to be removed from the
bottom of the unit near the outer edges. Try to remove all of the screws (they
are quite long), as this will make it easier to remove the side panel. This is
especially true of the screw at the front left.
With the unit sitting upright, gently
lift the top cover at the rear of the unit no more than 2-3 inches. Pull back on the
cover to remove it from under the front panel lip, being careful to move it
just enough to release it. These precautions are necessary due to the cable
attached to the Sony logo light on the top cover and connecting to the C board.
It is easy to rip off the female end of the connectors attached to the circuit
boards.
Remove the cable where it attaches to
the C board (CN305).
Remove the side cover,
starting at the right front, by gently tilting it upward and sliding it towards
the rear. The HA and HB boards are mounted on this side of the panel. There is
a connector at the very front on top of the HA board that must be disconnected
to prevent pulling out the LED indicator board on the front panel. This will
not damage anything, but the fan assembly will have to be removed to reinstall
the board. The other cable going from
the HB board to CN302 on the C board has adequate working length. This cable must
be plugged in for the unit to function.
The left side of the panel can now be removed. Disconnect the cable
running from the rear IR sensor by unplugging it where
it attaches to the C board (CN304). A plastic retainer holds this side in and
pushing inward towards the lens will release the lock. This is illustrated in
Figure 10-5. Gently lift the side panel slightly upward and then back and it
should release.
TOP COVER REMOVAL
RIGHT SIDE COVER REMOVAL
LEFT SIDE COVER REMOVAL
SERVICING PRISM BLOCK
The prism block assembly contains the
necessary mirrors to re-converge the red, green and blue light output from each
LCD panel and direct the sources to a single lens for projection of the image.
Under normal circumstances, this assembly should provide thousands of hours of
use. Improper maintenance by the end user (failure to clean or change air
filter on a regular basis), along with unusually long operating times (six or
more hours a day on a regular basis) can cause damage to the polarizing filters
for each LCD panel along with potential damage to the panels themselves. The
extreme heat generated by the lamp combined with the small confines of a
compact unit contributes to this.
Symptoms of heat damage to the LCD
panels and/or polarizing filters will vary depending on the amount of damage
they incur. In mild cases, a shift in white balance will occur. Severe cases
will cause blotches of discoloration on the projected image.
The structure of the light box
assembly uses dichroic and front-surface mirrors to split the white light from the
lamp into the necessary color spectrum for each LCD panel. The red LCD receives
light first. A slightly longer path is required for the green LCD with the blue
being the furthest from the light source. This arrangement creates a situation
where the red LCD and polarizing filters receive the most heat and are
therefore subject to damage easier than the other panels. The green follows
next, with the blue least likely to be affected. The blue could eventually be
damaged but the customer will invariably request service on the unit before
heat damage extends to this point. Identifying a potentially damaged LCD or
polarizing filter will be covered next.
IDENTIFYING PRISM BLOCK FAILURE
As mentioned earlier, shifts in color
balance and/or blotches of discoloration are signs of problems with the LCD panels
and/or polarizing filters. Although these symptoms could be caused by the video
processing or gamma correction settings, it is unlikely they are the cause
unless the customer or a technician unfamiliar with the unit has altered these
in any way.
The simplest procedure to isolate an
electronic problem is to unplug the flexible cables connecting each LCD panel
to the C board. Liquid crystals, by nature, reside in an aligned condition. The
application of voltages are what cause the “twisting” to block incoming light
at varying levels. By removing the cables, all light is allowed to pass through
the panels. If white balance or blotches of discoloration are still present,
the problem lies within the prism block. This is also a good way to identify
contamination from dust or other particulates.
EXAMINING THE PRISM BLOCK
Removal of the C board allows full
access to the prism block. There are two polarizing filters for each LCD panel
identified as “in” and “out”. The in-polarizing filters are located on the
outside of each LCD panel. They can be removed without having to remove the
prism block. By removing the single silver screw securing each one, they can be
lifted out for examination.
Note
that the screw hole in each polarizing filter is slotted, not round. This
allows for rotation of the filter and proper alignment to the LCD crystals. The
mounting screw will have made a small indentation in the plastic retainer of
the filter and serves as a positioning guide when it is re-installed Be certain
to install each filter in its correct location as they are unique to each color.
The filters will have a small colored dot on the bottom edge to identify it.
Heat damage to the filters will vary from mild
discoloration to severe melting of the film coating of the glass plate. Minor discoloration is difficult to see, but
can be more easily viewed if the filter is laid on top of a yellow colored paper.
White paper suffices, but yellow appears to be the most effective.
Two most common symptoms of heat
damage. The first figure has been enhanced with photo editing software to
exaggerate the symptom for illustration purposes. The discoloration is usually
subtle. The second figure illustrates
an extremely damaged filter. Extreme heating of the filter guarantees damage to
the LCD panel. Minor discoloration may or may not be an indicator of LCD
damage, but requires the removal of the prism block for further examination.
Heat damaged Polorizers
The
prism block is secured to the optical block by two 2.6X8mm black screws
positioned diagonally. Once these are removed, the prism block is easily lifted
upward.
The corresponding LCD panel for any
polarizing filter exhibiting heat damage should be closely examined for damage.
The most common symptom is a bubble easily seen on the surface of the panel. If
any surface flaws appear on a panel, the prism block must be replaced. If the
LCD panels appear intact, the required polarizing filter(s) can be replaced. As
noted earlier, failure to service the air filter is the most common cause of
heat damage to the prism block. It would be a good idea to remind the customer
of this. Customer maintenance procedures are clearly covered in the owner’s
manual.
TO ENTER SERVICE MODE
- The service mode on the VPL-HS20 is accessed through the customer menu. It is normally hidden from the customer’s view. Using the remote commander while the unit is powered up, press “ENTER”, “ENTER”, “LEFT” and “ENTER” in sequence. A prompt will appear on the screen asking if you wish to enter the factory mode.
- Press the “UP” key on the remote and the unit is now in service mode. This sequence will add two new groups to the customer setup menu. Press the “MENU” button to view.
Service mode cannot be entered if the
input selection is set to Memory Stick. If the unit has been unplugged from AC
power, it will enter this input by default. Select any other video input. While
you are pressing the key sequence, an “Invalid Key” prompt will appear on the
screen as you press each key. This is normal.
- The first group added displays information about the unit such as the ROM version, along with lamp and total operating hours. The second group displays a menu of items that can be adjusted and are usually performed when the prism block or B board is replaced. You should not have to perform these adjustments in most cases. Current service policy as of this writing requires that any confirmation of a prism block failure be sent to our CPC division in Laredo, TX.
TO EXIT SERVICE MODE
- Unlike all of the consumer televisions, the service mode is not exited automatically by turning the power off. The same key sequence as mentioned above must be repeated. The prompt will once again appear on the screen asking if you would like to return to the “user mode”. Press the “UP” key to hide the service adjustments.
LAMP TIMER RESET
Whenever the lamp is replaced, the lamp timer should be reset. With the unit in the “factory” mode, press “RESET”, “LEFT”, “RIGHT” and “ENTER” on the remote commander. Verify the lamp hours have been reset to zero in the service menu.
