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!

 
AAPL
$518.09
Apple Inc.
+0.13
MSFT
$40.02
Microsoft Corpora
+0.27
GOOG
$547.50
Google Inc.
+11.06

MacTech Search:
Community Search:

Software Updates via MacUpdate

PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
MYStuff Pro 2.0.16 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
TurboTax 2013.r17.002 - Manage your 2013...
TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more
TrailRunner 3.8.769 - Route planning for...
Note: While the software is classified as freeware, it is actually donationware. Please consider making a donation to help support development. TrailRunner is the perfect companion for runners,... Read more

Latest Forum Discussions

See All

Knights of Pen & Paper is Free for a...
Knights of Pen & Paper is Free for a Limited Time – Don’t Wait for a Natural 20, Get it Now! Posted by Rob Rich on April 16th, 2014 [ permalink ] | Read more »
R.B.I. Baseball 14 Review
R.B.I. Baseball 14 Review By Blake Grundman on April 16th, 2014 Our Rating: :: RETRO REVIVEDUniversal App - Designed for iPhone and iPad What was old is new again, as the MLB attempts to taking baseball gaming back to its retro... | Read more »
Noodlecake Studios Places Mikey Hooks on...
Noodlecake Studios Places Mikey Hooks on Sale, Releases Sneak Peek Trailer for Upcoming Sequel Mikey Boots Posted by Tre Lawrence on April 16th, 2014 [ | Read more »
Cosmic Mechanic Review
Cosmic Mechanic Review By Blake Grundman on April 16th, 2014 Our Rating: :: SLIGHTLY CREDIBLE MACHINEUniversal App - Designed for iPhone and iPad Creatives folks love the opportunity to have their wits tested, but there isn’t... | Read more »
ClutchPlay Games Releases Trailer for it...
ClutchPlay Games Releases Trailer for its Upcoming New Game, Skullduggery! | Read more »
Captain America: The Winter Soldier – Th...
Captain America: The Winter Soldier – The Official Game Review By Rob Thomas on April 16th, 2014 Our Rating: :: OUT IN THE COLDUniversal App - Designed for iPhone and iPad | Read more »
Strike Wing: Raptor Rising to Get a Huge...
Strike Wing: Raptor Rising to Get a Huge Update That Adds New Mode, Improved Graphics and More. Posted by Tre Lawrence on April 16th, 2014 [ | Read more »
Don’t be a Pygon, Download Horn Right No...
Don’t be a Pygon, Download Horn Right Now While it’s Still Free Posted by Rob Rich on April 16th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
RollerCoaster Tycoon 4 Mobile Review
RollerCoaster Tycoon 4 Mobile Review By Jennifer Allen on April 16th, 2014 Our Rating: :: DISAPPOINTINGLY WEAKUniversal App - Designed for iPhone and iPad The RollerCoaster Tycoon franchise finally comes to iOS, but it’s a rather... | Read more »
148Apps Live on Twitch: Pivvot’s Looper...
On our latest Twitch stream, we’ll be playing a pair of minimalist arcade games, one that just got a big content update in Pivvot, and another that was inspired by it in 15 Coins. Whitaker Trebella, creator of Pivvot, will discuss the new modes... | Read more »

Price Scanner via MacPrices.net

Apple refurbished iPad Airs available startin...
Apple is now offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. The following Airs are available today: -... Read more
21-inch 2.7GHz iMac on sale for $1179, save $...
B&H Photo has the 21″ 2.7GHz iMac on sale for $1179 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Add an iMac to your shopping cart, and B&H will offer an... Read more
Download our app, iTracx, for iOS and Android
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
Education discounts shave up to $300 off the...
Purchase a new Mac 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, and all... Read more
Save $50 on Mac mini Server
B&H Photo has the 2012 Mac mini Server on sale for $949 including free shipping plus NY sales tax only. Their price is $50 off MSRP. Read more
PhatWare’s “Ultimate Writing App For iOS” Ren...
PhatWare Corp. has announced it has renamed its new WritePro word processing app for iPhone and iPad: WritePad Pro. The decision to change the app’s name to leverages the strong brand awareness and... Read more
Full Resolution Photo Editor Tint Mint 1.0 Re...
California based independent developer, Jeffrey Sun, creator of the iOS app Modern Editor, has released Tint Mint, a new photography app for editing enthusiasts. The app costs a dollar, and it packs... Read more
16GB iPad mini (Apple refurbished) available...
The Apple Store has refurbished 1st generation 16GB iPad minis available for $249 including free shipping. Both black and white models are available. Read more
Save $120 on the 27-inch 3.2GHz Haswell iMac
B&H Photo has the 27″ 3.2GHz iMac on sale for $1679.99 including free shipping plus NY sales tax only. Their price is about $120 off MSRP. Read more
Using a Mac Doesn’t Eliminate The Heartbleed...
Low End Mac’s Dan Knight notes that any time you visit a website with an https: prefix or see that secure lock icon on your browser, some type of security software is busy trying to protect your data... Read more

Jobs Board

*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Market Leader - Cincinnati...
…challenges of developing individuals, building teams, and affecting growth across Apple Stores. You demonstrate successful leadership ability - focusing on excellence Read more
*Apple* Retail - Manager - SoHo - Apple (Uni...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
Position Opening at *Apple* - Apple (United...
**Job Summary** Every day, business customers come to the Apple Store to discover what powerful, easy-to-use Apple products can do for them. As a Business Leader, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.