TC1100 Repair Guide

The TC1100 has exhibited two different symptoms, related to the display that have a common cause and solution.

The Issues

The display of the TC1100 could show blue blocks in an alternating pattern on startup. Alternatively, the screen could just show random Unicode characters, such as delta, what was described as the symbol of Anubis, or the most common is accented characters. These characters will appear in random places on the screen.

Usually, these issues prevented the computer from booting.

The Cause

We have tied these issues to the graphics chip coming just barely unseated. This occurs because the motherboard is warped by pressure that occurs when the motherboard and assorted other pieces are screwed into the case, and the case shut.

The Solution

During testing we found that if the pressure on the motherboard was relieved, the chip would not be improperly seated, and thus the computer would be fine. As the issues were tied to the warping of the motherboard, two methods of fixing the problem were identified.

Relieve the Pressure

It is possible to relieve the pressure by adding washers under the motherboard, to sit between the motherboard and the pegs for the screws that attach the motherboard to the case. WARNING: These washers must be non-conductive, or small enough to not touch the other connections on the motherboard.

Add More Pressure

The other option to flatten the motherboard and prevent warping was to add more pressure near the back of the graphics chip.

The Process

Note: These instructions are not exhaustive. HP has published a very good guide to disassembling the TC1100. This is available from the HP website, and you should consult it. [[1]]

The process for disassembling the TC1100 is reasonably straight-forward. The TC1100 should be disconnected from any keyboard before the process begins. Lay the TC1100 so that the screen is on the table. There are 5 phillips-head screws holding the various covers to the case. Remove these carefully. Note that the battery is screwed in, as well as latched in. Do not try to pry the battery out. You could damage the battery.

Once the various covers are removed, remove the hard drive. Be careful to pull the plastic tab on the hard drive. Note that you must first pull the hard drive horizontally, to disconnect it from the ATA connector, and then the hard drive can be lifted out of the slot.

There is a plastic cover under the hard drive. Pulling this back reveals the digitizer cable, where it connects to the digitizer. There is a plastic tab attached to the connector. Use this to disconnect the cable.

Remove the 8 Torx screws that connect the two pieces of the case together. Note that while 6 are readily visible, two are slightly hidden. Flip up both legs; one of the screws is hidden under this. The other screw is hidden under the release slide for the hard drive. You will need to hold the slide back to remove the screw. If you do not have ready access to a Torx bitset, we found that a 2mm flathead screwdriver worked extremely well.

Open the connector cover and remove the pen. Remember, if you are having trouble separating the two halves of the case, check if the connector cover has closed on you.

Separate the two sides of the case. The easiest way to do this is to stand the tablet on edge, and locate the side that has the audio connectors. Gently insert a flathead screwdriver to assist you (the 2mm one used to remove the Torx screws works best). Once the gap between the pieces is about the size of the width of your screwdriver, i.e. you can rotate the screwdriver 360 degrees easily, you should be able to see the metal fingers that surround the audio connectors. The connectors are attached to one half of the case while the plastic that covers them and has the drawings on it is attached to the other side. Insert your flathead between the metal fingers surrounding the audio connectors and the plastic cover. The two pieces should easily separate. Do not apply to much pressure here. You could break pieces of the case. At this time, you do not need much force.

Now start following the split around the entire tablet. The corner that has the pen holder will be the hardest to separate. Leave this til last. We found that gently shearing the two sides back and forth can help, but it will still be difficult. Be gentle, but we found that more force was required here.

Once the two halves separate, you will thank us for having you diconnect the digitizer cable. As you can see, it connects both halves of the case, and would not let you separate them. There is another cable that connects both halves, and this is the audio cable. It can be disconnected by pulling up the plastic connector, and removing the cable, but this is not necessary. The two halves can be laid side by side, with the audio cable connecting them.

Now look for the graphics chip. It will not be obvious as it, and most of the other important components, are covered by a metal sheet. This metal sheet does not need to be removed. Each major chip is denoted by a dip in the metal sheet. If you are looking at the computer so that the external connector (monitor, ethernet, ...) are to your left, the graphics chip will be the closest chip to you on the right side of the sheet. It is one of the smaller dips in the metal.

To verify that you have found the graphics chip, connect and external monitor and power to the tablet. Turn on the tablet and verify that the symptoms are occurring, POST should be sufficient. Next, turn the tablet off (do this quickly as you do not have mouse or keyboard), and apply pressure to the back of the graphics chip, again determined by the external connectors being to your left. Maintain the pressure as you turn on the computer, and determine if the symptoms have disappeared. If they have not, turn off the computer and repeat the previous steps, applying slightly more pressure. Also, make sure that you have the correct chip. If the symptoms disappear, make sure that the result is repeatable. Turn the computer on and off several times, and ensure that the symptoms do not reoccur. You will need to maintain pressure during each cycle.

While the problem may resolve itself for a short period, we have found that they will come back. We have had longer term success with the fixes applied.

Our Solution

The ultimate resolution to this problem will depend upon your available resources. Due to our circumstance, we chose to apply more pressure to the chip. We achieved this by sandwiching a piece of half-inch diameter tubing between the two halves of the case. The tubing was obviously lying horizontal, so that pressure would deform it into a flatter piece, rather than a cylinder. This was placed near the back of the chip (back being determined by the side away from you, when the external connectors are to your left). For some of our computers, more than one piece of tubing was required, and so additional pieces of tubing were placed orthogonal to and on top of the preceding piece.

Once the tubing was in place, the two halves of the case were put back together, and one screw was used to secure the two halves. The screw hidden under the slide was very fortuitously placed, so only this screw was put back in. We then tested the display on an external display again. If the problem was fixed, we re-attached the digitizer cable (under the hard drive) and tested that the internal display also worked. If the problem remained fixed, then the other screws were reinserted, and one final test. If it was not successful, then another piece of tubing may be required.