[LisaFAQ] > [Hardware] > [Video and CRT]

3.16.3. How do I replace the Video Board?

DANGER: The following procedure is not to be taken lightly. It is fraught with high voltage and possible implosions. Negligence on your part, or even following these directions exactly as written could result in shards of phosphor-covered glass embedding themselves into your flesh or other unfortunate occurrences. I, Tom Stepleton, assume no responsibility for ANY result of following these instructions for replacing the video board on any Apple Lisa or any other purpose. DO NOT attempt this repair unless you are CERTAIN of what you are doing. I accomplished it solely from EXTREME caution and that foolish will a reckless teenager has. BE CAREFUL and do NOT perform this repair if there is a professional who will do it for you!!!

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Tools and Parts: Safety goggles, medium-shafted Philips-head screwdriver, medium-shafted flathead screwdriver, alligator-clip wire, Apple Lisa Video Board, film canisters (optional).

Always wear safety goggles during this procedure

Step 1: Unplug everything from the machine and wait at least one day after powering down the Lisa before repairing. The Lisa will not drain the anode or the high voltage capacitor on shutdown; a charge might be retained for extended periods of time! I took no chances and waited a week... there is no rush.

Step 2: Ground yourself and the Lisa chassis adequately and remove the rear panel of the Lisa by turning the two hand screws left and pulling. Pull out the card cage and set both aside. Remove the front panel and set it aside. Now, in the rear of the Lisa, locate the two screws in the air vents inside the top of the card cage cavity. Unscrew them; they will remain in the top of the cavity and will not fall. From the rear of the machine, lift up the top cover of the Lisa about two inches and slide it forward one inch. You may now lift off the top cover and set it aside. DON'T TOUCH ANYTHING YET

What you should see, looking from the rear of the Lisa: a metal sheet covering the card cage cavity and power supply at the bottom, the top of the Lisa Widget Controller to the far upper left (if you are using a 2/10), and the CRT cavity with the Video Board at the lower left, flyback coil underneath the neck of the CRT and to the right, and the speaker underneath the CRT at the upper right. There should be a large red wire emerging from the top of the CRT and going down into the flyback coil.

Step 3, Discharging the Anode: BEING ABSOLUTELY CERTAIN that the Lisa is connected to some sort of ground and that you are at no risk of shock, attach one end of the alligator-clip wire to the shaft of the flathead screwdriver and the other end to the metal frame of the Lisa. VERY CAREFULLY slide the screwdriver head underneath the red rubber suction cup, not forcing anything. A little over a half inch of my screwdriver went under when I did this. If there is any charge left in the CRT or the high-voltage capacitor, it will dispel with a small pop. It is a good idea to perform this operation even if you have left the Lisa unplugged for an extended period of time. Take no chances.

Step 5, Removing the CRT Neck Protector: In lieu of any technical term, I decided to call the small metal box-like enclosure that protects the rear end of the CRT the CRT neck protector. No matter what you call it, it needs to be removed, and to do this you must remove the screws that hold it. Before you do this, you must remove the main wires which go from the white CRT cap to the video board from the white clips on the CRT neck protector as well as the ground wire. Lift the main wires carefully from the clips, being careful to not twist the white CRT cap. After you have accomplished this, pull the white ground wire from the CRT neck protector. Now you can remove the screws. Some of these screws are accessed from the card cage cavity and some from the CRT cavity. Use the medium-shafted Philips-head screwdriver for this job.


Handyman Tom's Helpful Hint: Are you a shutterbug? If so, then you undoubtedly have lots of 
film canisters lying around.  Take as many film canisters as there are screws in your 
project, arrange then in a pattern similar to the places where the screws are located, 
then place each screw in its respective canister. Not only will the screws stay put, you also 
have a handy reference as to where to return the screws.

Step 6, Removing the Video Board Plugs: Locate the plugs going into the video board. There should be three of them: two smaller ones further up the board and one large one lower on the board. These are seated quite firmly and take some pulling to remove, and I had the blisters to prove it! Exercise extreme care, however, as there is a vacuum inside thin glass walls about three inches away! Also remember that printed-circuit board bends; when you're pulling, hold the PCB in place to prevent it from bending and subsequently cracking. After you have removed the first two plugs and remembered which sockets they belong to, prepare yourself for the monster eight-pin plug at the bottom. On the top and bottom there are two clips you must push in before you can remove the plug. I spent hours at this and suffered numerous blisters; for those of you wondering, wrapping your fingers in duct tape does not work. I eventually broke off one of the clips; all it took after that was some more pulling and the plug was finally free.

Step 7, Removing the CRT Cap: Locate the round white plastic cap on the tip of the CRT with the wires coming out of it. Ever so gently, being careful not to push or twist the cap, pull it away from the end of the CRT until the cap is completely off of the prongs. Set it aside. If the black plastic cap from inside the white cap still remains over the very tip and pins of the tube,VERY CAREFULLY and with VERY LITTLE PRESSURE use a knife to pry it away from the tip and pins, using a circular motion to keep pressure even on all sides. Please remember that there is a very thin wall of glass between the outside world and the vacuum in the CRT. Treat it as if it were tissue paper. The black cap may be brittle and it may fragment. If so, pry off the fragments with the knife, letting them fall into a paper cup for disposal.

Step 8, Removing the Video Board: First, remove the two screws near the top of the video board and keep them handy. Then, making sure that all wires connected to the Video Board are not obstructed and that all plugs are out, pull the Video Board from the socket at the bottom of the CRT cavity. Discard.

Step 9, Inserting the new Video Board: Making sure that all the wires connected to the new Video Board are not obstructed, lower the new Video Board into the socket at the bottom of the CRT cavity. Press firmly. Screw in the new Video Board with the same two screws you saved from before.

Step 10, Inserting the Video Board Plugs: Remembering which plugs went into which sockets, firmly insert the plugs into the video board, starting with the lowest plug, the 8-pin, and working up. Make sure that you check whether the plugs are going in right-side-up; although the plugs have guides you may still be mistaken. Look for two notches on the plug; this side is the top. The eight pin plug lacks these notches but rather has a bar across the two four pin plugs. This bar must be facing upwards.

Step 11, Replacing the CRT Cap: Making sure there are no tangles, draw the CRT cap back to the tip of the CRT, the wires forming a gentle curve, ready to be inserted into the clips on the CRT neck protector. Slowly and CAREFULLY slide the CRT cap onto the pins until they can no longer be seen, making sure not to twist the cap. DO NOT FORCE

Step 12, Attaching the CRT neck protector: Holding the CRT neck protector in place, screw in the top screw first, then the two screws in the CRT cavity adjacent to the CRT neck. Screw in the other screws. Gently, being sure not to pull or twist the CRT cap, place the wires in their respective clips.

Step 13, Closing the Lisa: Sitting behind the Lisa, draw the top cover over the forward bar until the plastic prongs take hold. Replace the screws inside the card cage cavity. Replace the front cover, the card cage, and the rear cover.

Step 14, Testing: Turn it on. Stand back. If it works, you'll know.

Source Tom Stepleton http://web.archive.org/web/19980212223305/galena.tjs.org/~tom/service.html

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