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
$99.18
Apple Inc.
-1.57
MSFT
$45.90
Microsoft Corpora
-0.46
GOOG
$568.27
Google Inc.
-9.09

MacTech Search:
Community Search:

Software Updates via MacUpdate

Cocktail Family License (5 Macs) 7.6.1 -...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Cocktail 8.0 Beta 2 - General maintenanc...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
QuickBooks 2015 16.0.0.1352 R1 - Financi...
QuickBooks 2015 helps you manage your business easily and efficiently. Organize your finances all in one place, track money going in and out of your business, and spot areas where you can save.... Read more
Mac DVDRipper Pro 5.0.1 - 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
Apple OS X bash Update 1.0 - Fix for sec...
The OS X bash Update fixes a security flaw in the bash UNIX shell on OS X 10.9.5 (also on OS X 10.8 and 10.7 [see Related Links below]). OS X 10.9.5 or later Downloads for OS X 10.8 and OS X 10.7 in... Read more
SyncTwoFolders 2.0.5 - Syncs two user-sp...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
FinderPop 2.5.7 - Classic Mac utility, n...
FinderPop is a Universal preference pane that extends OS X's contextual menus using a FinderPop Items folder much as the Apple Menu Items folder used to do for the Apple menu. It has other features... Read more
VueScan 9.4.45 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
LibreOffice 4.3.2.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
calibre 2.4 - Complete e-library managem...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more

Latest Forum Discussions

See All

Banner Saga (Games)
Banner Saga 1.0.17 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.17 (iTunes) Description: NOTE: The Banner Saga does NOT run on iPhone 4. iPhone 4S and more modern devices recommended. | Read more »
Beatbuddy HD (Games)
Beatbuddy HD 1.0.2 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.2 (iTunes) Description: **IMPORTANT** Beatbuddy runs only on iPhone 6, 6 Plus, 5, 5c, 5s, iPad 4, iPad Mini Retina and iPad Air. | Read more »
Spirits of Spring (Games)
Spirits of Spring 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: From the creators of the award-winning empathy game, Papo & Yo, comes a tale about finding strength. | Read more »
I am a brave knight (Games)
I am a brave knight 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Do you have ten minutes to live a life? | Read more »
iKeywi - Customizable 5-Row Keyboard (U...
iKeywi - Customizable 5-Row Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $.99, Version: 1.0 (iTunes) Description: Want to add an extra row to your iPhone/iPad? One of the most popular keyboard extension in iOS... | Read more »
Manage Your Cloud – Wunderlist Now Suppo...
Manage Your Cloud – Wunderlist Now Supports Dropbox Posted by Jessica Fisher on October 1st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Nexticy Review
Nexticy Review By Jennifer Allen on October 1st, 2014 Our Rating: :: IDEAL FORM CREATIONiPad Only App - Designed for the iPad Nexticy allows you to make your own forms for research purposes or to organize your business better. It’s... | Read more »
Tiny Troopers: Alliance Marches onto the...
Tiny Troopers: Alliance Marches onto the App Store Tomorrow Posted by Jessica Fisher on October 1st, 2014 [ permalink ] Tiny Troopers: Alliance, by Kukouri, is a | Read more »
HeroCraft Introduces Unlimited Sequel to...
HeroCraft Introduces Unlimited Sequel to WW2: Sandbox. Strategy & Tactics Posted by Jessica Fisher on October 1st, 2014 [ permalink ] | Read more »
RGB Express Review
RGB Express Review By Jennifer Allen on October 1st, 2014 Our Rating: :: DELIGHTFUL PUZZLINGUniversal App - Designed for iPhone and iPad Guide trucks along their delivery routes in RGB Express, a testing but charming puzzle game... | Read more »

Price Scanner via MacPrices.net

ASUS, Lenovo, and Amazon Slug It Out For Tabl...
According to market intelligence firm ABI Research, Apple and Samsung have led the touchscreen tablet market by a substantial margin since Apple energized the category back in 2010. However, ABI says... Read more
Amazon offers 13-inch MacBook Air for $899, $...
Amazon.com has the 13″ 1.4GHz 128GB MacBook Air on sale for $100 off MSRP including free shipping: - 13″ 1.4GHz 128GB MacBook Air: $899.99 Read more
Apple resting On Its iPhone Laurels? – The ‘B...
Apple calls its new iPhone 6 and 6 Plus “The Biggest Advancements in iPhone History,” but does reality live up to the hype? “Seldom have so many waited so breathlessly for so little,” tweeted veteran... Read more
Roundup of Apple Mac and iPad Education disco...
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
Apple Boycotts German Magazine Computer Bild...
Apple has revoked its PR accreditation of Germany’s Computer Bild, Europe’s best-selling PC magazine, in reaction to Bild’s posting of a “#Bentgate” YouTube video. Axel Telzerow, editor in chief of... Read more
iPhone 6 & iPhone 6 Plus Available in Chi...
Apple has announced that iPhone 6 and iPhone 6 Plus will be available in China beginning Friday, October 17 from the Apple Online Store (http://www.apple.com), Apple’s retail stores, and an expansive... Read more
MacBook Airs on sale for $100 off MSRP, start...
Best Buy has the new 2014 MacBook Airs on sale for $100 off MSRP on their online store. Choose free home shipping or free local store pickup (if available). Prices valid for online orders only, in-... Read more
Apple Releases OS X Mavericks bash Update 1.0...
Apple has released a patch update for OS X Mavericks users to address the recently-detected “Shellshock” security bug in BSD UNIX’s bash shell. Apple says only a few Mac users who had manually... Read more
Pivotal Payments Ready for Apple Pay – FlexPo...
Pivotal Payments, a provider of merchant services and global payment processing solutions, has announced its proprietary FlexPoint platform will support credit and debit transactions through Apple’s... Read more
iStabilizer Announces Tabarm — First Friction...
iStabilizer, a specialist in universal lightweight compact tripods, steady cams, dollies, mounts, and remotes for smartphones, tablets, and cameras, announced today the iStabilizer tabArm, the first... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*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
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, 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
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.