If you are reading this, odds are you have a Cisco IP phone that is in relatively good condition, the only problem with it is the hookswitch mechanism is messed up and therefore the phone is prettymuch useless. This is common on Cisco phones. Today I will specifically cover how to disassemble a Cisco 7970 phone and troubleshoot the hookswitch mechanism. With a little patience you can take apart the phone and revive the hookswitch with a little cleaning.
***WARNING*** I TAKE ABSOLUTELY NO RESPONSIBILITY FOR ANY DAMAGE TO YOUR PHONE. PROCEED AT YOUR OWN RISK. ALSO BE AWARE THAT THIS MAY VOID YOUR WARRANTY!!
NOTE: The procedure for the 7970 series phones is somewhat different than the Cisco 7940/60 7941/61 7942/62 series phones. I have not taken apart any of the 42/62 series, but the 40/60 & 41/61 series do not have a bezel or screws on the front side.
First, unplug all cables from the phone and flip it over so the back (non button side) is facing you. There are 4 screws to remove on the back. Two in plain sight, two under the rubber feet near the bottom rear of the phone.
You can pull the top half of the rubber feet back to reveal the screw holes.
Once you have removed the rear screws, flip the phone over so the front (button side) is facing you. Now you need to temporarily remove the bezel that surrounds the screen and overlays the softkeys and line buttons.
Start at the top and gently pry the bezel out from the phone. Once the top is lifted away, gently pull the bezel up and away. There are five small tabs at the bottom that hold it down and into the phone case.
Once the bezel has been removed, you will see three screws along the top (above the screen). Remove these screws.
There is one final screw that is behind the little receiver clip. Gently pop the receiver clip off and remove the screw that is under it. Note on the photo below the grime that has accumulated around the handset cradle area. My opinion is that this is probably what causes a lot of the damage to hookswitches. I have noticed that this is more prevalent on ladies phones, I assume that this is most likely from makeup that has rubbed off onto the handset and then transferred onto/into the phone.
Once these screws have been removed flip the phone back over so that the back of the phone (the non-button side) is facing you. Gently pry the rear cover from the phone. Be careful as you remove the cover. There is a small tension spring that applies pressure to the hookswitch. Be sure it doesn’t get lost. Also make a note of how the tension spring is attached.
Once the back has been removed, remove the tension spring. You can now remove the hookswitch activator. On the 7970 you can swivel it 90 degrees and remove it. On the 7940/60 41/61 series it is easier to remove the hookswitch board screw and pull the hookswitch board out from under the hookswitch. Once this is removed, clean any grime/goo, etc., that has accumulated around the hookswitch opening and on the hookswitch activator itself.
If you haven’t already removed the hookswitch board, remove it. Unscrew the screw in the middle of the board, and follow the hookswitch cable down to where it plugs into the main processor board of the phone and unplug the cable. Remove the hookswitch board.
Once you have the hookswitch board/cable assembly removed, there is a small rubber piece pressed into the board. Gently remove it by simply prying it away from the board.
Once you have it removed, clean the metal contact points on the board with an eraser. Be sure not to leave any eraser residue on the contact points. I also like to clean the rubber piece with an alcohol pad.
The trickiest part is getting the rubber cover back on the board. Once you have thoroughly cleaned the contact points and the rubber cover, align the rubber cover properly with the holes on the board. It will only line up one way. Gently press the small rubber protrusions back into the hookswitch board. This isn’t easy. Once you have wiggled them into the board enough that they protrude out the back side a little bit, take some needle nose pliers and pull them thru until the rubber cover is pressed back flat against the hookswitch board.
Once you have cleaned and reassembled hookswitch board, simply reverse the steps above to reassemble the phone and you are done!
For the Cisco cleaning guide click here