Cisco 7940-60 disassembly

These are instructions on how to perform basic disassembly (or tear down) of the Cisco 7940/7960/7940G/7960G phones. It may be applicable to other Cisco phones. It may not be applicable to all hardware revisions of the listed phones. This is useful for checking wires or cleaning spilled soda out of the keys on the phone.

Taking your phone apart certainly will void almost any warranty, and it is very easy damage your phone so that it no longer functions. Any actions performed are done at your own risk, and you assume all responsibility for any actions and liabilities taken by following these instructions.

Directions here are given where the "top" would be the highest point of the phone while the phone is in it's normal fully upright position. "Bottom" indicates the lowest point of the phone while the phone is in it's normal fully upright position. Place the phone face down with the top of the phone facing away from you. From here, the direction "left" is used to indicate the left side of the person working on the phone. "Up" is used to indicate the direction away from the center of the Earth.

It is not necessary to remove the stand to disassemble the phone. To remove the stand, adjust it so that is lays flat against the back bezel. There are two plastic pins that hold the stand to the phone. To release these two pins, use a knife (or some other thin edged object) to wedge in between the pin's head and the plastic edging to pry the 2 pin heads towards each other. They are not spring loaded so once one side is released, you can proceed towards the other side.

The panel on the back bezel that surrounds the 2 RJ45 and 1 RS232 ports does not need to be removed to perform any useful function. It's removal provides a clear view of the daughter card that the RJ45/RS232 ports are located on, but does not provide good access to one of the two gold screws that hold the daughter card in place. The panel can be removed by placing a knife (or some other thin edged object) in the small relief located on the side of the panel closest to the bottom of the phone. Lift the bottom edge of the panel away from the phone about 5 mm so it's edge clears the edge of the bezel. Then slide the panel towards the bottom of the phone. The panel will come loose after sliding about 5 mm.

There are 4 identical black screws holding the back bezel to the front bezel. 2 of the screws should be immediately visible down long circular holes nearest the top of the phone. The other 2 screws are located under the rubber foot pads at the bottom of the phone. Only the half of the rubber pads towards the top of the phone need to be unstuck to access the screws. The screws are all standard Phillips head screws that must be rotated counter-clockwise to release.

Once the 4 screws have been removed, the back bezel is still held in place by 4 tabs along the top of the phone. 2 tabs are located on either side of the display, and two are located at the top of the handset holder. To release the tabs, lift the part of the back bezel that is towards the bottom of the phone a few millimeters. Then slide the back bezel towards the bottom of the phone. The two tabs behind the handset holder can offer some resistance so the may have to be worked on some. Care must be taken though not to break off the tabs.

There are three cables that connect the system board to other components on the front bezel. Looking at the board, there is one in the lower left corner with two wires colored black and white. On the right are two connectors. One has a four wire gray ribbon cable with red stripe along one edge going to the handset switch. The other has two wires, black and white, that go to the speaker-phone module. These should be removed before removing any screws. If you only need to make a quick fix to the front, the two on the right, or the one on the bottom left can remain connected while the board is removed.

There are total of 9 screws holding the system board to the front bezel. There are two types of screws, long and short. 7 of these screws have a circular white outline around the screw hole and are long. 2 of these screws have a square white outline around the screw hole and are short. the screws are silver in color. With these screws removed, the board should release strait out easily.

With the system board out of the way, the rubber sheets between the buttons and the board is visible. The lower/larger sheet wraps around 3 screw mounts and 6 pin hole mounts. There is on pin hole on the left that is unused. The upper/smaller rubber sheet is secured with two pin hole mounts. The rubber sheets should remove easily to reveal the plastic buttons. These buttons fall out easily so take care if you want to leave them in place.

I used the above information to disassemble my 7970G. However the 7979 does not have 4 tabs but more screws on the front.

This is all facing the phone from the front:

you have to get the front grey part off since there are 3 bolds beneath it (no tabs those are only on the handset holder). The grey front has 3 'tabs' so you have to pull it away from the phone upward a little (the tabs are about a cm deep) and then you can slide the whole grey front off to the top.

Below the handset is also one screw. You have to press the button of the horn down and slide the small peace beneath the horn button and speaker up so you will enveil the screw.
Created by: atamido, Last modification: Sun 20 of Jun, 2010 (16:35 UTC) by esperanto
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