Philips DPTV305, User Manual

Page: 24 / 1848

B. Removing the PTV Coupling Fluid
All repairs made to the CRT/optical block assembly require the removal of the coupling fluid. The following
procedure describes how to remove the PTV coupling fluid.
1b) Lay the CRT assembly on its side with the plug pointing up.
2b) Remove the plug (X8).
3b) Remove some of the fluid from the coupler to prevent spillage when the CRT is removed. An empty
coupling fluid bottle with a cone top is recommended to lower the fluid level within the coupler. Squeeze
and hold the bottle and insert the tip of the cap into the drain hole of the coupler. Loosen the grip on the
bottle, allowing the fluid to be pulled up into the bottle. Save the fluid.
4b) Reinstall the plug (X8).
5b) Stand the CRT assembly up with the neck of the CRT pointing up.
6b) With an awl or marking pen, outline the edges of the CRT onto the coupler.
Note: The correct positioning of the CRT to the coupler is critical to the optimum performance of the optical
system.
7b) Remove the four CRT mounting bolts (A) (with springs and spacers) and remove the mounting bracket
(D).
8b) Remove the four CRT mounting ear screws.
Note: The CRT mounting ear screws are not used on some assemblies.
9b) Gently remove any metal shavings from around the screw holes. Do not allow the metal shavings to get
into the fluid.
10b) Note the position of the high voltage anode cap with respect to the coupler.
11b) Carefully remove the CRT from the coupler. Wipe any excess fluid from the faceplate of the CRT. Set the
CRT aside.
12b) Use an empty coupling fluid bottle to extract the remainder of the fluid from the coupler.
Note: Complete removal of the coupling fluid is not necessary when only replacing the CRT.
13b) Clean any remaining fluid from the coupler and the CRT gasket channel using absorbent tissue. Refer to
"C". Cleaning the Coupler, C-element Lens and CRT Faceplate procedure if the fluid is discolored or
contaminated.
14b) Make all necessary repairs.
C. Cleaning the Coupler, C-element Lens and CRT Faceplate
1c) Remove CRT coupling fluid as described in steps 1b through 13b.
2c) Using denatured alcohol on a cloth made of 100% cotton or a lens cleaning tissue, gently clean the C-
element (fisheye) lens, coupler and the CRT faceplate. Thoroughly clean the coupler assembly, including
the expansion chamber bladder, and allow to fully dry.
Caution: Do not use soap or detergent type substances to clean the coupler and its related assemblies. Water
can be used as an alternative to denatured alcohol, but the assemblies must be completely dry prior to
reassembly of the coupler and the addition of the coupling fluid. A hair dryer may be used to dry the
coupler and its assemblies prior to reassembly. If contaminated fluid is discovered, the coupler and its
related assemblies must be completely disassembled and cleaned to prevent a reoccurrence.
3c) Replace the CRT and C-element lens gaskets.
4c) Reassemble the C-element lens and the output lens to the coupler.
5c) Refer to "Replacing the CRT Coupling Fluid" upon completion of necessary repairs and cleaning of the
optical/coupler assemblies.