TweetFollow Us on Twitter

Keyboard repair
Volume Number:5
Issue Number:1
Column Tag:The Electrical Mac

Keyboard Repair

By Richard Clark, Mission Viejo, CA

The Incredible Dying Keyboard

I have a confession to make - I don’t own a Mac Plus. What I do have is an ancient 512Ke which began life as an early 128K. It’s had two power supplies (“analog boards” to those in the repair business), two keyboard cables, a new 512K mother board, and an Incredible Dying Keyboard. A different key dies about once a month now; there’s no warning, the key just stops working.

The Incredibly Frustrating Repairman

Fixing a broken key is supposed to be simple for the repairman - you just open up the keyboard, remove the old switch, and solder in a new one. It’s a five minute job, and that includes waiting for the soldering iron to warm up. There’s only one problem: “the rest of us” can’t get the special keyboard switches that Apple uses. After a run-in with one particular dealer who refused both to sell individual switches and to fix the keyboard (he wanted to sell a new keyboard for $130), I decided to open up the keyboard and see what I could do.

Fixing Dead Keyboards is Easy (and cheap)

I learned that, with some limited soldering and mechanical skills, most keyswitch problems can be fixed. You remove the switch, make an adjustment or two, and replace it in the keyboard. It’s easy and works almost all of the time. So far, I’ve managed to repair 11 out of 12 dead switches myself (and the one failure was because I tried a shortcut which damaged the switch beyond repair.)

Notice that these repair techniques only work in the case where the switch is the culprit. Also, I haven’t tried these with one of the new ADB keyboards, but Apple seems to be using the same switch supplier, so this should work. Also, these techniques may not apply to “locking” keyswitches (like the Caps Lock). If the entire keyboard is dead, then I can’t help you (except to say “take a good look at your keyboard cable” because if you stretch the cable too much you can pull the connections apart inside of the clear connectors.) If the whole keyboard is dead, and it isn’t the cable, then you’ll need a new keyboard since Apple doesn’t supply the spare parts for fixing the keyboard electronics to anybody.

Now that we’ve gotten the disclaimers out of the way, we’ll discuss what you’ll need. First, you’ll need some basic soldering equipment: a soldering iron, solder (use only rosin-core solder, not acid-core) , and some sort of solder remover. The vacuum-type removers seem to work better than “solder wick” for keyboard work. A small can of flux remover (sold in Radio Shack as “cleaner/degreaser”) is optional but helps tidy up the keyboard after you’re done.

You’ll also need some basic tools and supplies: a medium-sized Phillips screwdriver (about 1/4”), two or three small straight-blade screwdrivers (about 1/8” across), a pair of needle-nose pliers, and a pair of scissors or an X-Acto knife. You’ll need two small pieces (about 3“ each) of wire, stripped at both ends. And, depending on the problem you’re fixing, you’ll need either a small tube of cement or some self-adhesive labels.

Finally, you’ll need to know how to solder and unsolder on single-sided printed circuit boards. Anybody who’s built a Heathkit or two will understand how to do this. If you’ve never handled a soldering iron before, then get a friend to help.

The Secret Life of Keyswitches

OK, if you’ve gotten this far, then you’re interested in fixing keyboards. So let’s talk about how keyboards work. Looking at Figure 1, you can see that a keyswitch consists of five major parts: the upper and lower case sections, the stem, a spring, and a “contact assembly”. The contact assembly consists of a plastic frame containing two metal pieces shaped in such a way that when you press on the front of the assembly, the metal pieces come together and close the switch. When you press down on a key, the stem travels downward, resisted by the spring, and presses on a small metal tab sticking out of the front of the contact assembly. This compresses the assembly and closes the switch. When you remove your finger, the spring pushes the stem back up which removes the pressure from the contacts and opens the circuit again. The keyswitches are wired to an “encoder” which turns the switch closure into a signal for the Mac.

So, how does a keyboard break? Well, there’s 2 common problems: if the switch just quits working (or works only if you press the key hard and/or wiggle it around), then the contact assembly is wearing out. Or, if the key seems to be “floating” - that is, the keycap is a little higher than all of the others and is putting out multiple characters on each press - then the upper and lower case assemblies have come apart and aren’t guiding the stem properly. Both of these problems are easily fixed.

Fixing Keyboards: Step by Step

So, here’s the step-by-step procedure for repairing a Mac keyboard:

1. Organize your tools and plug in the soldering iron. Detach any cables connected to the keyboard.

2. While the soldering iron is warming up, turn the keyboard over and remove the 5 phillips-head screws holding the bottom of the keyboard case on. Remove the bottom casing and set it aside, then lift out the keyboard assembly. Set the top casing aside with the bottom casing.

3. Using a flat-blade screwdriver, pry up the key cap from the broken key and any surrounding key caps that might get in your way.

4. Turning the keyboard over, locate the 2 pins coming out of the broken switch. (I typically circle them with a pencil after I find them, just so I don’t have to search for them several times.) Unsolder these connections, being careful not to overheat the connection and lift the foil up off of the board.

5. Using a pair of needle-nose pliers, gently move the unsoldered pins to be certain that they are completely free from the sides of the hole.

6. Turn the keyboard back over, so that the key caps are on top. Referring to Figure 2, press in on the 2 tabs at the top and the bottom of the switch. While you are pressing these tabs inwards, lift out the switch. Please resist the temptation to use pliers on the stem of the switch - you could break or damage the stem beyond repair. Having a second person comes in handy here!

7. Now that you have the switch out, you can begin the repair. If the problem is a “floating” keyswitch, then just glue the top and bottom halves of the switch together (making sure that all of the pieces are inside, of course), and skip the next step. If the problem is the more common “dead switch” type, then do the following:

a. Using a pair of small screwdrivers (X-Acto #2 knife blades also work well), and looking at Figure 3, insert the blade of the screwdrivers between the gray tabs and the black upper body. Press the blade all the way down to the bottom of the case on both sides and the two halves will pop apart. Pull the case halves apart, being careful not to lose the small spring.

b. Stack 2 or three layers of self-adhesive paper labels together (I use a spare disk label), and cut it to about 3/8” square - a little smaller than the back of the contact assembly. Then, referring to figure 4, stick this paper “shim” to the back of the contact assembly. When a keyswitch dies, it’s usually because the contact assembly has nothing to press on behind it. The labels provide the necessary backing.

c. Carefully re-assemble the switch. Because of the labels, it may take a little pressure to get the top and bottom casings back together. Don’t forget to install the spring!

8. Now it’s time to test your work. Using the 2 pieces of wire, solder one end of each to each of the pins on the back of the switch. Solder the end of one wire to one of the pads on the keyboard where the switch was soldered, and solder the other wire to the other pad. Now plug in your keyboard, turn on your Macintosh, and test out a few keys, including the one you just modified. If the modified key fails, then take it apart and check your work. Re-assemble it again and try again.

9. Unsolder the wires from the keyboard and keyswitches. Then check that the pins are sticking straight out from the back of the switch and straighten them if necessary. Next, put the switch back into the hole in the keyboard where you removed it. Make sure that the pins in the switch enter the holes in the circuit board, and press the key in until the gray tabs snap into place.

10. Re-solder the switch into place and (optionally) spray a little flux remover on the connection just to clean things up. If you use cleaner, be careful not to get any inside the switch!

11. Re-assemble the keyboard, and you’re done!

The whole process should only take about a half hour the first time you do it, and about 10 minutes each time after. As I noted before, I have 11 keys on my keyboard modified this way (fixed with a stack of paper labels), and the earliest repairs have been working perfectly for a year now.

Unlike most MacTutor articles, you won’t be getting a program listing with this one! So I hope that knowing how to fix your own keyboards will satisfy both you and David Smith. Happy Hacking!

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Capo 3.2 - Slow down and learn to play y...
Capo lets you slow down your favorite songs so you can hear the notes and learn how they are played. With Capo, you can quickly tab out your songs atop a highly-detailed OpenCL-powered spectrogram... Read more
OmniOutliner 4.2.3 - Organize your ideas...
OmniOutliner is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more
pwSafe 4.0.1 - Secure password managemen...
pwSafe provides simple and secure password management across devices and computers. pwSafe uses iCloud to keep your password databases backed-up and synced between Macs and iOS devices. It is... Read more
WALTR 1.5.4 - Drag-and-drop any media fi...
WALTR is designed to make it easy to upload and convert any music or video file to an iPad or iPhone format for native playback. It supports a huge variety of media file types, including MP3, MP4,... Read more
Audio Hijack 3.1 - Record and enhance au...
Audio Hijack (was Audio Hijack Pro) drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio... Read more
PopChar 7.1 - Floating window shows avai...
We're also selling a 5-license family pack for only $25.99! PopChar helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to... Read more
BBEdit 11.1.1 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
Picasa 3.9.139 - Organize, edit, and sha...
Picasa and Picasa Web Albums allows you to organize, edit, and upload your photos to the Web from your computer in quick, simple steps. Arrange your photos into folders and albums and erase their... Read more
Mac DVDRipper Pro 5.0.5 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
NetShade 6.2 - Browse privately using an...
This promotion is for NetShade and 1 year of Proxy and VPN services NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN... Read more

Block Fortress has a Big New Update for...
Block Fortress is a survival-style game that's as fun as it is blocky. It's also just gotten a rather sizeable update that adds a lot more cool stuff. [Read more] | Read more »
Simple and Surreal Star Base Sim rymdkap...
I really like rymdkapsel. Not just because I'm a sucker for games that are cleverly simple or highly stylisitc, but because it's fun and challenging. Actually it's extremely challenging, which is why I was excited to learn that it's getting a couple... | Read more »
Check out the anticipated Angel Stone in...
Fincon has finally revealed Angel Stone in action in the first ever official gameplay trailer for the anticipated hack and slasher. Angel Stone is set in a post-apocalyptic world in which humanity is in danger of being wiped out by the demonic... | Read more »
Moleskine Timepage is an All-New Calenda...
Moleskine Timepage is a bit of a departure for the notebook manufacturer (since it has little to do with notebooks), but it certainly carries their simple and elegant style quite well. [Read more] | Read more »
Jog on Over and Check Out the New Runtas...
Runtastic has put out a fair number of apps to help you sleep, track excercise, and train various parts of your body. Now it's time for your legs to have their own time in the spotlight with Runtastic Leg Trainer. [Read more] | Read more »
It's Lights Out in the Upcoming Pla...
Ember’s Journey is a stark puzzle platformer with a twist: the entire game is played in darkness. The only light you can see by is the one emanating from your own character. [Read more] | Read more »
MooVee - Your Movies Guru (Entertainmen...
MooVee - Your Movies Guru 1.0 Device: iOS iPhone Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: MooVee helps you effortlessly manage your movies, on your iPhone. | Read more »
Geometry Wars 3: Dimensions (Games)
Geometry Wars 3: Dimensions 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Enjoy the next chapter in the award-winning Geometry Wars franchise and enjoy stunning, console-quality... | Read more »
CHAOS RINGS Ⅲ (Games)
CHAOS RINGS Ⅲ 1.0.0 Device: iOS Universal Category: Games Price: $19.99, Version: 1.0.0 (iTunes) Description: The newest addition to the popular smartphone RPG series is finally here! ・CHAOS RINGS Overview | Read more »
The Popular Insight Series of Travel Gui...
Getting around in a country when you can't understand the primary language can be tough. Fortunately there are several options available to help wold travellers with the important stuff like giving directions to a cab driver or asking where the... | Read more »

Price Scanner via MacPrices.net

Apple restocks refurbished Mac minis for up t...
The Apple Store has restocked Apple Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz... Read more
13-inch 2.4GHz Retina MacBook Pro (refurbishe...
The Apple Store has 2013 Apple Certified Refurbished 13″ 2.4GHz/128GB Retina MacBook Pros available for $879–$320 off original MSRP. Apple’s one-year warranty is standard, and shipping is free: - 13... Read more
Apple refurbished iPad Air 2s now available f...
The Apple Store is now offering Apple Certified Refurbished iPad Air 2s for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: -... Read more
MacBook Airs on sale for up to $80 off MSRP
Save up to $80 on the purchase of a new 2015 13″ or 11″ 1.6GHz MacBook Air at the following resellers. Shipping is free with each model: 11" 128GB MSRP $899 11" 256GB... Read more
Free Glide Live Video Messaging App Brings Ne...
Glide, an Israeli startup whose popular live video messenger has attracted more than 15 million users, has released significant updates to its free iOS app. Glide for iOS now gives users more control... Read more
Top Markets Saturation To Slow Global Smartph...
According to a new mobile phone forecast from the International Data Corporation (IDC) Worldwide Quarterly Mobile Phone Tracker, smartphone shipments are expected to grow 11.3% in 2015 — down from 27... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Apple refurbished 2014 13-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and... Read more
What Would the ideal Apple Productivity Platf...
For the past four years I’ve kept a foot in both the Mac and iPad camps respectively. my daily computing hours divided about 50/50 between the two devices with remarkable consistency. However, there’... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Program Manager, *Apple* Community Support...
**Job Summary** Apple Support Communities ( discussions. apple .com) helps customers get the most from their Apple products and services by providing access to Read more
Senior Data Scientist, *Apple* Retail - Onl...
**Job Summary** Apple Retail - Online sells Apple products to customers around the world. In addition to selling Apple products with unique services such as iPad Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.