| Mirror cell modification
by Warp. The fan was mounted on a black disc of "architects' project board #4" purchased at a local art/crafts store. Very sturdy board about 1/8" thick. There are two layers of board separated by a sheet of "dynamat" vibration dampening rubber sheeting used by autosound dealers to dampen vibrations in door panels for those with overly loud woofers. Check with your local high-end auto sound dealer. The mat is sandwiched between the two layers of black archetects board.
The board is 36"x40" for $10.95. The autosound dealer gave me the 12" square piece of dynamat out of scrap.
I used a low profile 4.5" square by 3/4" deep 24v dc box fan with ball bearings: $6.95 at local electronics hobby shop. The polarized plug was $.75 and the switch was $1.50.
I wrapped the circumference of the fan with the dynamat (it is self adhesive on one side), cut a hole to fit the fan and secured it with a bead of acrylic based paintable caulk. On the inside (side toward the primary) I cut four triangles with one edge notched so I could slide them under the corners of the fan and give it something to actually bolt to with 8-32 machine screws and nuts. Between the triangles and the main disc was another layer of dynamat (just afix it to one side of each of the four mounting triangles. I filled any gaps with the acrylic caulk, gave all "paper" surfaces two coats of polyurethane sealer, sprayed the internal side with Krylon Ultra Flat Black. Repainted the main cell with Rustoleum Hammered Metal, masked off the internal black circle and sprayed with Krylon Satin Black. Be sure to mask off the acctual fan opening when painting so you get no paint on the blades or internal channels.
The reason I chose a 24 volt fan was that my power supply has 3, 6, 9 and 12 volt outputs. At 12 volts it is very smooth - moves lots of air and is quiet. It also runs at 6 and 9 volts that gives me actually 3 speeds. Even when viewing, at the 6 volt setting you get air flow to prevent thermal layers and no visible vibration.
Before you buy the fan, have the dealer hook it up so you can hold it and insure that it is well balanced.
The newer LXD55's have gone to a newer primary cell arrangement in which there is a large metal ring underneath the primary. It has a rounded edge which causes the air current from the fan to "air foil" up and around and come across the face of the primary which should prevent thermal boundry layers from forming. I don't really plan on having it on much while doing serious viewing - mainly just to reduce cool down time.
On the outside of the fan, there is a removable square guard held on by 4 nylon thumb screws. I have cut squares of filter material from furnace "allergy filters" to mount under this guard for air filtration and to keep dust out of the OTA. One $6.00 filter from Home Depot cut into 16 filter squares with more left over.
Another hint: Under each Collimation Screw (large screws) there are two nylon washers (Home Depot - 3 for $.90) which make the screws turn a lot smoother and keep them from eating into the paint of the primary cell.
If you need larger full size pics, email me and I will send them.
Warp
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