TweetFollow Us on Twitter

ADB Repair
Volume Number:5
Issue Number:11
Column Tag:The Electrical Mac

Related Info: ADB Manager

Repairing the ADB

By Eric Schlienger, Champaign, IL

ADB Repairs

[Eric Schlienger received a BSEE at the University of Colorado at Boulder in 1979. He was in charge of the both the control system design group and the software group of Retech Inc. of Ukiah CA. He has worked primarily with Hewlett Packard computers until he went back to school at the University of Illinois at Champaign-Urbana. He is currently working towards a Ph.D. in Materials Science and Engineering.]

Several months back I was doing some work on my brand new Mac II and started experiencing a “scritchy” mouse. Considering myself a clever fellow, I decided to clean it during a particularly lengthy recompilation of all my code. Since I was being clever I decided I might be lazy as well and so I did not unplug my mouse. Similarly I used whatever implement was at hand for the cleaning operation; in this case a pair of metal microscopy tweezers. Well to make a long story “short” I slipped....OOPS! Both keyboard and mouse took an immediate trip to Lala land, terminating my programming session rather abruptly. Terminal ADB failure.

While reading February ’88 MacTutor, I noticed that several other folks have experienced the same ADB symptoms, and although their method of generating an ADB failure would appear to be less certain than mine, I am convinced that they may be able to repair the situation with a $0.79 fuse in 15 minutes. ( or have their service man do it) As a new motherboard is probably more expensive and less readily available, I believe that some people might find the repair procedure interesting.

Before attempting a repair, do be certain that you have checked all cabling and preferably tried a different mouse and keyboard. If you have verified that the problem is indeed with the ADB, you are then ready to Open The Box.

The Tools

First off, you will need a few tools. These are an ohm meter, a Phillips screwdriver, small needlenose pliers, small diagonal cutters, a small soldering iron with solder, a felt pen, a container for screws, and 1 ounce of ethanol (you may choose the flavor). It is also best to buy the fuses you need before you open the box. These fuses are referred to as PICOFUSES, and they are rated 1A 125V. They are roughly the size of a 1/4 watt resistor. The manufacturer of the ones I bought is Littlefuse Tracor.

Finding The Fuses

To begin, clear a large area for storage of the Monitor, Keyboard, Mac II top cover, the Drive platform (drives still attached) and the cables. Please note that the floor does not qualify as a storage area; neither tennis shoes nor carpet fuzz are items that are regularly found in properly functioning computers. As such it is best to avoid circumstances where they might be introduced.

If necessary park the heads on your hard disc. Unplug the CPU and remove all cables. Move the keyboard, mouse, monitor and cabling to the designated Storage-Area-Not-On-The-Floor. Pick up the CPU and turn it 180° such that the back is facing you. Remove the screw located in the top center of the back panel (Fig 1.).

Then turn the CPU back around. Reach around back and depress the two cover latches and swing the top up. Continue to swing the top up and give it a jiggle to free it from the front of the CPU case.

Behold the inner workings of the Mac II. If you become nervous, sit down and consume the ethanol while reminding yourself not to touch any of those neat chips. With the felt pen, mark the outside of the floppy disc cable where it plugs into the mother board. (This is so you are confident which way it goes back in.) Write down the number of the socket that the cable is plugged in to on the cable itself. Gently grasp the plug where it goes into the socket and pull it out; DO NOT PULL ON THE CABLE! If you have a hard disc (you probably do), mark the power plug and the SCSI ribbon cable and remove them in a similar fashion. Verify that all devices on the drive platform have been disconnected from the motherboard.

Remove the four platform mounting screws and lift out the Drive platform (Fig. 2). Place it gently in the Storage-Area-Not-On-The-Floor.

OK. Now look at Figure 3. With the aid of this drawing you should be able to locate the devices labeled F1 & F2. The “F” stands for fuse. (Clever these Apple folks, huh.) In my case, F2 was blown.

It may be that F2 is the ADB fuse, and F1 is the fuse for the Serial Ports, but I haven’t verified this one way or the other. With your ohm meter you should be able to test the fuses. The basic procedure is to measure the resistance of the fuse. If the resistance is greater than one ohm, it is bad. (Actually it should be zero.) If both fuses test good, put everything back together, obtain more ethanol and prepare to pay big bucks for a motherboard.

Fixing The Fuse

If a fuse is bad you have two options. The first is to find a static free workstation and remove the motherboard to replace the fuse. In this case you desolder the old fuse and install the new one. The second method is something of a kludge, but functional, safer and easier. Basically what you are going to do is to piggyback the new fuse on top of the old fuse. Since a blown fuse is an open circuit piggybacking is the functional equivalent of replacing it. However for those who regularly give tours of the inside of their computer, it should be noted that this repair may be esthetically deficient. The procedure is fairly simple:

Take one of your new fuses (they come in a box of 5) and using the needlenose pliers, bend the leads 90° on either side of the fuse body. About 1/4 inch below the fuse body bend the leads 90° such that the leads are now at a right angle to the fuse body (Fig 4).

Trim the leads so that the distance to the last bend to the end is about 1/4 inch. Slide the leads under the old fuse at either end, and grasping each lead in turn with the pliers, pull it through until the new fuse is over top of the old one. Bend the leads up and solder them into place on the old fuse. When soldering don’t use too much heat as you do not want to remove the old fuse from the mother board. When the new fuse is securely fastened to either end of the old fuse trim off the excess leads.

Reposition the drive platform, replace the 4 mounting screws, replace the drive cabling. Put the front of the cover in place and swing down. A gentle tap may be required to get the front to seat properly. Replace the rear screw and the cables. Your ADB should be repaired.

Please note that the presence of a piggy backed fuse will almost certainly void your warranty, so if your computer is fairly new consider having an authorized service man do the repair. If it is out of warranty and the alternative is a new motherboard, you might give it a look see. Please remember that while the box is made to be opened, the circuitry is not hardened against standard computer room contaminants such as coffee, donut crumbs or peanut butter sandwiches. So don’t leave the computer disassembled so that everyone can see your handiwork and comment on how clever you are.

As a general rule, do not mess with the ADB or associated devices when the power is on. This should hopefully eliminate the need for ADB repairs.

 
AAPL
$105.22
Apple Inc.
+0.39
MSFT
$46.13
Microsoft Corpora
+1.11
GOOG
$539.78
Google Inc.
-4.20

MacTech Search:
Community Search:

Software Updates via MacUpdate

OS X Server 4.0 - For OS X 10.10 Yosemit...
Designed for OS X and iOS devices, OS X Server makes it easy to share files, schedule meetings, synchronize contacts, develop software, host your own website, publish wikis, configure Mac, iPhone,... Read more
TotalFinder 1.6.12 - Adds tabs, hotkeys,...
TotalFinder is a universally acclaimed navigational companion for your Mac. Enhance your Mac's Finder with features so smart and convenient, you won't believe you ever lived without them. Tab-based... Read more
BusyCal 2.6.3 - Powerful calendar app wi...
BusyCal is an award-winning desktop calendar that combines personal productivity features for individuals with powerful calendar sharing capabilities for families and workgroups. BusyCal's unique... Read more
calibre 2.7 - 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
Skitch 2.7.3 - Take screenshots, annotat...
With Skitch, taking, annotating, and sharing screenshots or images is as fun as it is simple.Communicate and collaborate with images using Skitch and its intuitive, engaging drawing and annotating... Read more
Delicious Library 3.3.2 - Import, browse...
Delicious Library allows you to import, browse, and share all your books, movies, music, and video games with Delicious Library. Run your very own library from your home or office using our... Read more
Art Text 2.4.8 - Create high quality hea...
Art Text is an OS X application for creating high quality textual graphics, headings, logos, icons, Web site elements, and buttons. Thanks to multi-layer support, creating complex graphics is no... Read more
Live Interior 3D Pro 2.9.6 - Powerful an...
Live Interior 3D Pro is a powerful yet very intuitive interior designing application. View Video Tutorials It has every feature of Live Interior 3D Standard, plus some exclusive ones: Create multi... Read more
The Hit List 1.1.7 - Advanced reminder a...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
jAlbum Pro 12.2.4 - Organize your digita...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more

Latest Forum Discussions

See All

Rami Ismail Opens Up distribute​() for D...
Rami Ismail Opens Up distribute​() for Developers Posted by Jessica Fisher on October 24th, 2014 [ permalink ] Rami Ismail, Chief Executive of Business and Development at indie game studio | Read more »
Great Hitman GO Goes on Sale and Gets Ne...
Great Hitman GO Goes on Sale and Gets New Update – Say That Three Times Fast Posted by Jessica Fisher on October 24th, 2014 [ permalink ] | Read more »
Rival Stars Basketball Review
Rival Stars Basketball Review By Jennifer Allen on October 24th, 2014 Our Rating: :: RESTRICTIVE BUT FUNUniversal App - Designed for iPhone and iPad Rival Stars Basketball is a fun mixture of basketball and card collecting but its... | Read more »
Rubicon Development Makes Over a Dozen o...
Rubicon Development Makes Over a Dozen of Their Games Free For This Weekend Only Posted by Jessica Fisher on October 24th, 2014 [ permalink ] | Read more »
I Am Dolphin Review
I Am Dolphin Review By Jennifer Allen on October 24th, 2014 Our Rating: :: NEARLY FIN-TASTICUniversal App - Designed for iPhone and iPad Swim around and eat nearly everything that moves in I Am Dolphin, a fun Ecco-ish kind of game... | Read more »
nPlayer looks to be the ultimate choice...
Developed by Newin Inc, nPlayer may seem like your standard video player – but is aiming to be the best in its field by providing high quality video play performance and support for a huge number of video formats and codecs. User reviews include... | Read more »
Fighting Fantasy: Caverns of the Snow Wi...
Fighting Fantasy: Caverns of the Snow Witch Review By Jennifer Allen on October 24th, 2014 Our Rating: :: CLASSY STORYTELLINGUniversal App - Designed for iPhone and iPad Fighting Fantasy: Caverns of the Snow Witch is a sterling... | Read more »
A Few Days Left (Games)
A Few Days Left 1.01 Device: iOS Universal Category: Games Price: $3.99, Version: 1.01 (iTunes) Description: Screenshots are in compliance to App Store's 4+ age rating! Please see App Preview for real game play! **Important: Make... | Read more »
Toca Boo (Education)
Toca Boo 1.0.2 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0.2 (iTunes) Description: BOO! Did I scare you!? My name is Bonnie and my family loves to spook! Do you want to scare them back? Follow me and I'll... | Read more »
Intuon (Games)
Intuon 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Join the battle with your intuition in a new hardcore game Intuon! How well do you trust your intuition? Can you find a needle in a... | Read more »

Price Scanner via MacPrices.net

Weekend sale: 13-inch 128GB MacBook Air for $...
Best Buy has the 2014 13-inch 1.4GHz 128GB MacBook Air on sale for $849.99, or $150 off MSRP, on their online store. Choose free home shipping or free local store pickup (if available). Price valid... Read more
Nimbus Note Cross=Platform Notes Utility
Nimbus Note will make sure you never forget or lose your valuable data again. Create and edit notes, save web pages, screenshots and any other type of data – and share it all with your friends and... Read more
NewerTech’s Snuglet Makes MagSafe 2 Power Con...
NewerTech has introduced the Snuglet, a precision-manufactured ring designed to sit inside your MagSafe 2 connector port, providing a more snug fit to prevent your power cable from unintentional... Read more
Apple Planning To Sacrifice Gross Margins To...
Digitimes Research’s Jim Hsiao says its analysts believe Apple is planning to sacrifice its gross margins to save its tablet business, which has recently fallen into decline. They project that Apple’... Read more
Who’s On Now? – First Instant-Connect Search...
It’s nighttime and your car has broken down on the side of the highway. You need a tow truck right away, so you open an app on your iPhone, search for the closest tow truck and send an instant... Read more
13-inch 2.5GHz MacBook Pro on sale for $949,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $949.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $150 off MSRP. Price is... Read more
Save up to $125 on Retina MacBook Pros
B&H Photo has the new 2014 13″ and 15″ Retina MacBook Pros on sale for up to $125 off MSRP. Shipping is free, and B&H charges NY sales tax only. They’ll also include free copies of Parallels... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
Textilus New Word, Notes and PDF Processor fo...
Textilus is new word-crunching, notes, and PDF processor designed exclusively for the iPad. I haven’t had time to thoroughly check it out yet, but it looks great and early reviews are positive.... Read more
WD My Passport Pro Bus-Powered Thunderbolt RA...
WD’s My Passport Pro RAID solution is powered by an integrated Thunderbolt cable for true portability and speeds as high as 233 MB/s. HighlightsOverviewSpecifications Transfer, Back Up And Edit In... Read more

Jobs Board

*Apple* Solutions Consultant - Apple Inc. (U...
…important role that the ASC serves is that of providing an excellent Apple Customer Experience. Responsibilities include: * Promoting Apple products and solutions 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
*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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.