Nimitz Digital Projector Cart How-To


Nimitz Elementary Parent Teacher Association, 545 E. Cheyenne Dr, Sunnvyale, CA 94087

NIMITZ COMPUTER PROJECTOR CARD HOW-TO

by James C. Liu, Nimitz Parent
v1.0 - 2008 January 14
webmaster@nimitzpta.org

Introduction: The Nimitz PTA authorized in Late Fall 2007, the purchase and donation of some number of digital projector carts to the school for use in the classroom. The idea then was to provide several digital projector carts capable of displaying visual presentations and playing multi-media for an entire class. The design, layout and components chosen considered elements of cost, usability, durability, compatibility, and anti-theft. The total budget for this project had a limit of $6000. The results, if favourable, would hopefully serve as a template for future school projector cart purchases.

In the second week of January 2008, the PTA delivered a total of 4 finished digital projection carts that came to a total of under $5900. The staff found the price/performance and usability of these carts to be initially very favourable. As such, the school is planning to move ahead and add more carts using these as a model.

The following summary provides a detailed "How-To" document for purchasing and constructing the Nimitz PTA digital projector cart.

Required Parts for the Cart:

Required Tools and Parts for Assembly:

philips screw driver #2
power drill with bits to drill 1/8", 5/8" and 3/4" holes.
diagonal cutters
sturdy scissors
small adjustable crescent wrench
box cutter/utility knife
2-part paste epoxy - 30 min-2hr set time (Target/Walmart/Home Depot)
zip ties in 4", 8", and 12" (Fry's/Home Depot)
double-sided padded adhesive (Target/Walmart/Home Depot/Office Max/etc)
#10 washer and #10x1 inch round head philips wood/metal screw (Home Depot)
Labeling and engraver to mark major components against theft.

Assembly Tips

1. Assemble the cart as directed. However, to make the joints permanent, we will mix a two-part paste epoxy. Do NOT use regular liquid epoxy mixes as they run and will seep out of the joints. Use a quality paste epoxy where both components are in small tubs and not syringes. Use a piece of scratch paper or an old magazine and mix equal parts of resin and activator. Scoop using different, clean mixing sticks (e.g. popsicle sticks) and mix thoroughly for a minute in a ventilated room. Avoid breathing fumes. Spread just a few dabs on the outside of the shelf feet and the insides of the tubes and slide on. If the tubes are difficult to push in, use a mallet and give it some light taps. When the tube is fitted, twist to spread the epoxy evenly. Repeat for each joint.

Note that the AV Projector Cart comes with a set of Long, Medium, and short legs. We will use the short legs and the long legs. Also, there are a pair of plain wheels and a second pair of locking wheels. The locking wheels should be on the same side of the cart as the handle on the top level so that the person pushing the cart by the handles can step and lock the wheels. (See figure 1, below).

Fig. 1 - side schematic of the projector cart

2. Unbox the projector, the computer, keyboard, mouse, LCD monitor Mac Mini, and speakers. Lay the projector, keyboard and LCD monitor on the top shelf approximately as show. (See figure 2, below). Use 1 inch squares of double sided mounting adhesive foam tape or equivalent and place at the base of the LCD monitor (hidden from normal view) and then firmly plant monitor onto top shelf. Drill a pilot hole with 1/8 inch bit through the monitor base near the mid-front. Refer to the RED dots for rough locations. Do NOT penetrate all the way through the shelf base. Using a #10x1inch long round head screw and #10 washer, tighten the screw and feel it drive into and through the shelf. The screw should be snug. Do NOT over-tighten as this may crack the monitor base.

Unpackage the security cable kit and take out one of the microclips and spreat it into a V-shape to insert into the security slot in the projector. You will find this slot near the mid rear panel on the unit. Pinch the microclip back so the cable-run holes line up. Position the projector as show in Fig. 2. Its position should be right up to the front lip of the cart, and offset a couple inches to the "port" side (i.e. left side) of the cart if pushing the cart. Now mark where the cable run hole in the microclip is pointing toward the top shelf surface and drill a 7/32 inch diameter hole. Approximate location is again, show by another RED dot on the diagram (see Fig 2.)

Place the projector in place, and then take the satellite speakers out and position them also on the top shelf. One of these speakers has the power On/Off button, volume control and bass control. This should be on the starboard (right) side of the cart. Route the audio cables between LCD and projector and through the built-in cabling hole and down to the middle level.

Do NOT attach any other cables yet.

Fig. 2 - top shelf layout

3. For the middle layer, the process is similar to top layer. There is a Mac Mini, a power strip, and the Mac's big AC Power brick. Place the MacMini down so the front DVD/CDROM slot is facing starboard (i.e. right side if pushing the cart). The Mac Mini should be closer to the stern of AV Cart so it's easy to reach in and turn on the Mac Mini which has a power button in the far rear. The position only needs to be approximate.

Like the projector, we will insert a security cable micro-clip in the back of the Mac Mini (just above the USB ports). And using our eyeball, we try to drill a hole that lines up with the micro-clip cable run hole. To avoid damage to the Mac Mini, move it out of the way before the drill bit penetrates through the base and up.

We will also need to drill a large 3/4" hole (using a keyhole spade bit) on the port (left) side of the middle layer. This hole will allows the security cable as well as the audio speaker and power wires to pass down to the subwoofer at the base level. Lastly, eyeballing again the position, we drill 4 holes (7/32 inch diam.) from underneath which we will use to secure the power strip.

Thread the subwoofer speaker cable with large head down through the 3/4 inch hole to the bottom shelf. Do NOT cable up anything else.

Fig. 3 - middle shelf layout

4. We shouldn't need to drill the last layer. Instead, we should use the supplied wood screw and metal anchor collar that came with the security cable kit and screw it to the base of the cart. The location for collar is flexible. Typically it should be adjacent the subwoofer (see RED dot below in Fig. 4).

Fig. 4 - bottom shelf layout

5. Zip-Tying the power strip. If the 4 holes you drilled line up well, then we should be able to take some two-side adhesive foam tape, peel and stick these to the bottom of the power strip, and then fix this to the bow (front) of the middle shelf. The outlets should be oriented so the ground wire is facing outward. This only works for outlets that are oriented perpendicular to the strip itself (i.e. latitudinal orientation). Some power strips orient the outlets parallel (i.e. longitudinally). In this case, simply route the power cord of the strip to the starboard (right side where we will swing it around and over the MacMini and plug it into the Projector Cart's main power 3 socket power strip. A power strip is necessary for our setup because the Cart only has 3 sockets built-in which could supply the Mac Mini, LCD monitor and the projector. But we have speakers that need power as well. In addition, a good power strip will have surge protection which will protect our projector carts against minor power surges.

6. Cabling - We start by inserting the security clips. The security cable kit comes with 2 micro-clips in the package and we should have purchased a 3rd clip for each Projector cart. These clips slide into and anchor in the back of the projector, the LCD flat panel monitor, and the Mac Mini. Start at the bottom level and loop through the anchor collar, then bring the cable up and through the middle shelf, then through the back of the Mac Mini clip and then forward and up through the hole in the top shelf and though the clip for the Projector. Bring the cable up and then back down through the clip for the LCD panel. Finally, the cable should go through the large built-in cabling hole, through the 3/4 inch hole for the subwoofer audio cable, and then back through the cable loop, where we will slide on the retainer square key washer, and then pad-lock the key washer.

Now we start on the top shelf and cable the power for the LCD monitor and the projector. Then we connect the VGA (i.e.Video) cables. The thinner, usually, blue-headed VGA cable goes from the projector's VGA-OUT (right-side socket) to the LCD's VGA-IN. The thicker, more shielded VGA cable which is all black, should go from the Projector's VGA-IN (left side socket) and down through the cabling hole to the back of the Mac Mini. The Video cables have the same head on either end and so it should not matter which end you connect. The VGA plug that goes into the Mac Mini must first plug into a DVi-to-VGA adapter supplied with the Mac Mini (a small 2 inch wide white plug). That adapter goes into the the back of the mac mini. Tighten all thumb screws to prevent cables from falling out.

Plug the projector, LCD and Mac Mini power plugs into the power strip and then nicely bundle all the excess black VGA and power cables togther in one or more compact bunches between top and middle layers. Use long zip-ties to secure the wiring and cables. Pull the zip-ties snugly and trim off tag end.

Next, route the mouse cable around the LCD and down through the same cabling hole in the top shelf. The keyboard cable goes directly down through the same hole. When plugging the USB plugs into the back of the mac mini, any socket is okay. But to allow easiest access to an open USB port for someone to upload, say, a presentation from a USB Flash drive, then it's better to plug the mouse and keyboard into the ports closest to the middle. You may need to shift the security cable and micro-clip a little to make room for the USB plug to fit. There is usually a green audio mini-jack which would plug into the headphones port.

Repeat the bundling operation again with mouse, audio wires, and keyboard wires. But use smaller size zip ties. When completed and laid out cleaning on the top surface, take larger zip ties and zip tie the smaller bundle with the larger bundle.

7. Finally, we should cut out small squares of double-side foam adhesive and adhere this to the bottoms of the Mac Mini, the satellite speakers, the subwoofer, and the Mac Mini power supply brick. And then lastly, we would use a label printer and/or engraver to mark the expensive components conspicuously.

First Boot and Config of Software

To turn on the system, plug in the main cart cord. Turn on the system in the following order: LCD monitor first, Mac Mini second, and the Power button on the projector 3rd. Optionally, you may also want to push and activate the speaker power and just leave it in the on position always. There is a built-in plastic cover over the projector lens. Simply touch the top plastic ridge above the lens and slide the cover to the side.

The first boot will take a while as the Mac configures its OS. For Network information, we can always go back and configure it, so we click in the lower left for "Other Network configuration" or something like that. For registration information, we enter:

First Name: Nimitz
Last Name: Elementary
545 E. Cheyenne Dr.
Sunnyvale, CA 94087
408-736-2180

short name (i.e. login): teacher
password: ******** (see Dale Jones or James Liu)
Password Hint: see (Dale Jones or James Liu)

To turn off the system, use the Mac's Main Menu in software and shutdown the computer gracefully. It is bad to force power-cycle a computer using the power button - unsaved data may not have been flushed to the disk from memory. Turn off the LCD monitor, and then push the power/standby button on the projector. You will be prompted if you really want to shut down the projector? Press power/standby again to confirm. The projector fan may continue to run for a few minutes to cool down the bulb and projector chassis. If you have time, allow it to do so. The fan will automatically power-off by itself. Slide the lens cover back closed.

Do NOT place items on the cart that would impede airflow behind the projector, around the mac mini, or above the LCD flat panel. This can permanently overheat and damage the equipment.

Volume Control - As mentioned above, the speakers have their own volume control on the right (starboard) speaker base. Power button, bass level and volume are present. But the speakers only amplify the signal they are sent by the Mac Mini. The Mac's output level has a software control. You must go the System Preferences menu and select "Sounds" an configure the output volume higher in some cases so sufficient signal is produced by the Mac for the speakers to amplify.

Hooking up another laptop - The projector supports native XGA resolution (i.e. 1024x768 pixels) and is compatible with potentially higher resolutions. It is possible to hook up a different laptop to the projector system and not use the Mac Mini. This is most easily done with a spare 3 - 6 ft male-to-male VGA cable. The other VGA cables are zip-tied in place making it hard to connect to a laptop that is not directly adjacent the projector; also, there is little space on the cart to place a laptop. Place the cart close to a desk near the front of the class or adjacent a table.

Before beginning, please poweroff the Mac Mini in software if it is currently on, then the LCD panel and then the projector. Next, disconnect both VGA connectors from the back of the projector. Using a spare male-to-male VGA cable, connect the video output of the laptop to the Video/VGA-IN port on the projector. Next power on your laptop if it wasn't powered on already and power on the projector. To output signal to the external VGA port on your laptop, you may need to hit a number of key sequences (e.g Function+F5 or something - look for Function keys that have monitor symbol). You may need to press the Function key multiple times to toggle from laptop display to external display to both display.

Mac PowerBook users with DVI output only need to use a DVI to VGA adapter to output to this projector. These are sometimes available at Fry's for about $20 - $30 and $15 - $20 online.

If you need power to recharge the battery on a notebook computer, you may use any of the 3 free sockets on the cart (at least one on the power strip, and 2 on the cart's mini power strip).

FAQ

A. Why not just buy a bunch of projectors without carts?
Loose projectors require a great deal of setup, cabling and do require that we issue laptops to each teacher or make it available. A cart that was on wheels, pre-wired, and networked with standard methods for media transfer (e.g. cdrom, dvdrom, or usb flash stick) would allow lesson plans to move forward quickly without lost time for setup.

B. What affected the choice of projector?
Our choice of projector was based on cost, native XGA (1024x768) support, and user web reviews on the product. There are more and more new projectors that take SGVA (800x600) and support higher resolutions by scaling, but the output is inevitably grainy or fuzzy, or worse, the scaling support is limited to only certain laptops or graphics chips and otherwise offsets the image or clips the image, forcing teachers into a waste of time to get the picture to sync up on the projector. We wanted native XGA resolution and in a projector with good response time, contrast, and ease of use. While most projectors do come with RCA jacks to hook up a DVD or VHS tape player, we also wanted a VIDEO splitter with VGA-OUT built-in which would save $30 on a separate, bulky cable. The Sanyo PLC-XW55 was the only new projector we could find at the time, to fulfill this need, and then there were a number of refurbs that we also considered such as the Sharp XR-10X. But The Sanyo was smaller, very quiet, newer with more contrast and response range and it got rave reviews. Also, some of the refurbs required the purchase of a new bulb, or came with a used bulb with less of a warranty. This made the cost of a refurb uncompetitve.

C. Why did you buy a small LCD flat panel?
For the cost of $160, we could have almost purchased 19 inch LCD flat panels. But we had 2 issues. The primary issue was usability. When the native resolution of the monitor is different from the projection source, it inevitably makes either the projector or the LCD display re-scale from the native resolution. Teachers would then possibly be required to waste time yet again trying to fiddle around with projector settings and monitor settings to sync rate and pixel dimension mismatches. We wanted to avoid that and go with a WYSIWYG philosophy (What You See Is What You Get). Next, the surface of our projector cart had limited space. We didn't want a Honkin' big LCD. In fact, that would further block the view so that students at the back of the classroom would have further problems looking over the cart to see the screen.

D. Why did we choose the cart height like we did?
As mentioned in the assembly instructions, we ordered adjustable carts but chose Short + Long support configuration instead of adding a Medium + Long, which would have made the carts another foot taller. The reasoning was simple. We prototyped a cart, moved it forward near the front of the class, then crouched down to the typical height of a 3rd grade child behind the projector and varied distance from immediately behind to all the way at the back of the class. A tall cart would disadvantage at least several of the students in the class depending on seating arrangement so we chose to lower the cart. But we could go too low. We averaged the height of the teachers and staff. This came to about 5ft 5 inches. Standing at arms length, we wanted to make sure the monitor was still visible at maximum tilt up. To low, and teachers might need to hunch down. We also tested the height so if a teacher had a stool was sitting, could she/he use this cart. A lower cart was more favourable as well.

E. Why choose Mac Minis and not something else?
Clearly, all the software in our District and most at our school runs on Mac. Also, with the prevalence of PCs and malware that attack PCs over networks, we wanted something more maintenance free like UNIX and something where we didn't need to upgrade and pay for virus security packages annually. Since the new MacOS X is BSD UNIX/Mach micro-kernel based, we liked the more hands-off maintenance. We had a choice of Mac Minis as well as Mac Books. The Mac Books were substantially over $1000, even at the low end. The lowest-end Mac Mini plus a small LCD monitor was just $750 and more capable (i.e. faster Core 2 Duo CPU, 1 GB DDR2 RAM, bigger HD, etc.) And by serendipity, we managed to order these during a transition where the low-end Mac Mini retailing for $600 had just been up-rev'ved to 1.83GHz Core 2 Duo (over the older 1.6GHz) and memory was up'ed to 1GB from 512 MB, and I think disks went from 60GB to 80GB for the same price. And then we managed to get the same or better price online (although it took some time) from eBay-express ($573 includes shipping/handling no tax - out of state) than any educators discounts or rebates ($575 before shipping/tax). Also, the Mac Minis, come with WiFi built-in, which means these carts will be truly mobile.

F. What was our security model? How much deterrence?
Nimitz is part of the famous Cupertino Union School District. Our demographics pretty much are upper-middle class, Silicon Valley types. Median Home prices are about $700K per 1000 sq. ft of living space. We have some low-income rentals with a good fraction of Title 1 kids in our school. But these are typically kids with parents motivated enough to move into our district. We don't have a high theft or crime rate. But that doesn't mean that we don't have crime. So the philosophy here was one of mild deterrence. Small computers, compact digital projectors are worth something on eBay and very liquid. Our goal was to prevent casual snatch and grab, which is accomodated well with a security cable with hardened metal clips and a padlock. Our design also integrated this cable through several levels of the cart via drilled holes and a screw mount metal collar. This doesn't prevent a conspicuous snatch-n-grab using a big SUV and throwing the whole cart into the back, but that would be an unlikely (although non-zero) risk at our school. To prevent theft of keyboards, mice, and speakers, we threaded the cables through a level of the cart as well and zip-tied them together in many places, requiring someone carefully cut in many places to remove them. Also, we used adhesive mouting strips to make sure speakers, monitor, power supply, mac mini, etc. were mounted firmly on the cart and the cart itself has epoxy at the joints to make life difficult. This will help keep components in place when pushing the cart on bumpy sidewalks. It will take force to rip the adhesive off or the velcro pads off and this requires more intent. In a higher crime school, it's possible to spend more assembly effort to align, drill and screw down components from underneath. There are also commercial brackets that can be used to secure the mac mini, and thicker cables to fix the monitor and projector. Also labelling and destructive engraving of school property deters resale of the component on the open market. To do the engraving, we used a $20 battery powered cordless Dremel tool with a cutting bit and a small diameter wire brush bit.

G. Can this be used for Assemblies and larger groups?
Short answer is yes. The projector is highly capable as long as the room is relatively dark. The audio speakers will be too low power, except for a classroom. But that can be solved with an adapter that goes from a stereo-mini-jack to audio input RCA or larger jack connecting to a larger amplifier.

H. Does this play movies?
Yes. Mac has DVD playing software included and pre-installed. We test each unit by booting, configuring and sticking some multi-media disk into the unit as a test of audio and video. Note, if someone has configured the screen saver, it may cut in during DVD play. Please disable the screen saver before starting a long movie.

I. I sometimes see a warning floating on the LCD panel but not the projector. Why is that?
Most likely, the LCD display is warning you that the projector is not outputting a signal within the preferred tolerance for vertical/horizontal sync rate. In other words, the LCD display doesn't like the projector signal output because it's either too slow or more likely, too fast. A bad sync rate can burn out a monitor so the warning should be heeded. Most likely, the best way to avoid this problem is to always power on the LCD display first, then turn on the projector and computer. This way, the LCD will have power and respond to inquiries by the projector on what its preferred sync rate is, and then the projector can respond and emit the preferred signal. If you see this warning, simply put the projector back into standby (push power/standby button once - wait a second then press again). Wait 10 seconds, then try to power on again. It may take 30 seconds for the Xenon discharge lamp to reach critical arc'ing voltage again, but that's normal. Hopefully, the LCD warning will be gone.

J. How much effort does it take to assemble a cart?
It takes one person about 3 - 4 hours to assemble the first cart, and about 2 hours for each on there-after. This can vary depending on one's level of confidence and skill with tools, home improvement, and computers.

K. How do we show power-point presentations?
The cheapest way is to go to www.OpenOffice.ORG and download the office suite for Mac OS X (versions available for Windows, Linux, and Solaris too). It's free, and compatible with Microsoft's suite. This should be able to load and play PowerPoint presentations as well as allow staff to produce presentations and save as PowerPoint files. This can save $hundreds on licensing costs for actual Office productivity software. If you have a site license or valid copies of MS Office for Mac OS, then by all means install and use them as well.

L. How do we share files?
The easiest way would be to setup the wired- or wireless networking in all the classrooms and provide a fileserver for download. The planned implementation at Nimitz is to setup wireless networking with a Web server which will act as an upload and download repository. This can take some expertise to setup. When we have such as system in place, we plan to open source the software for that as well. This will most likely run on a UNIX-based OS with Apache web server using Jakarta-Tomcat J2EE servlets and JSPs for portability.

M. Is there someone to contact for systems and architecture expertise for my IT Projects?
Try sending email to webmaster@nimitzpta.org and someone within the Nimitz PTA may be able to help you or direct you to the correct people.