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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

PDFKey Pro 4.3 - Edit and print password...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Kodi 15.0.beta1 - Powerful media center...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
DiskCatalogMaker 6.4.12 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
Macs Fan Control 1.3.0.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
Lyn 1.5.11 - Lightweight image browser a...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
NeoOffice 2014.11 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LaunchBar 6.4 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Remotix 3.1.4 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
VOX 2.5.1 - Music player that supports m...
VOX is a beautiful music player that supports many filetypes. The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all... Read more

This Week at 148Apps: May 18-22, 2015
May Days at 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out above the... | Read more »
Biz Builder Delux (Games)
Biz Builder Delux 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Ah, there's nothing like the rhythmic bustle of a burgeoning business burg... especially when you're the one building it... | Read more »
Auroch Digital is Bringing Back Games Wo...
| Read more »
Blades of Brim is a New Endless Runner f...
SYBO Games, the minds behind the ever-popular Subway Surfers, have announced their latest project: Blades of Brim. [Read more] | Read more »
Carbo - Handwriting in the Digital Age...
Carbo - Handwriting in the Digital Age 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Draggy Dead (Games)
Draggy Dead 1.1 Device: iOS Universal Category: Games Price: $.99, Version: 1.1 (iTunes) Description: Ditch your dead end job and take up a rewarding career in Grave Robbing today!Guide the recently deceased to a fun filled life of... | Read more »
Bad Dinos (Games)
Bad Dinos 1.0.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Apple Watch isn't Great as a Fi...
| Read more »
Show the World What You See With Stre.am...
Live broadcasting is getting popular on mobile devices, which is why you can now get Stre.am, by Infinite Takes. [Read more] | Read more »
PhotoTime's 2.1 Update Adds Apple W...
The latest PhotoTime update is adding even more functionality to the handy photo organizing app. Yep, including Apple Watch support. [Read more] | Read more »

Price Scanner via MacPrices.net

12-inch MacBook stock status for Monday, May...
The new 12″ Retina MacBooks are still on backorder at The Apple Store with a 3-5 week waiting period. However, a few models are in stock today at Apple resellers. Stock is limited, so act now if you’... Read more
New 27-inch 3.3GHz 5K iMac in stock with free...
Adorama has the new 27″ 3.3GHz 5K iMac in stock today for $1999 including free shipping plus NY & NJ sales tax only. Adorama will include a free copy of Apple’s 3-year AppleCare Protection Plan. Read more
Memorial Day Weekend Sale: New 27-inch 3.3GHz...
Best Buy has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary... Read more
OtterBox Maximizes Portability, Productivity...
From the kitchen recipe book to the boarsroom presentation, the OtterBox Agility Tablet System turns tablets into one of the most versatile pieces of handheld technology available. Available now, the... Read more
Launch of New Car App Gallery and Open Develo...
Automatic, a company on a mission to bring the power of the Internet into every car, has announced the launch of the Automatic App Gallery, an app store for nearly every car or truck on the road... Read more
Memorial Day Weekend Sale: 13-inch 1.6GHz Mac...
Best Buy has the new 13″ 1.6GHz/128GB MacBook Air on sale for $849 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Memorial Day Weekend Sale: 27-inch 3.5GHz 5K...
Best Buy has the 27″ 3.5GHz 5K iMac on sale for $2099.99 this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-store prices may vary.... Read more
Sale! 16GB iPad mini 3 for $349, save $50
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model. Read more
Price drop on 2014 15-inch Retina MacBook Pro...
B&H Photo has dropped prices on 2014 15″ Retina MacBook Pros by $200. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 save $200 - 15″ 2.5GHz... Read more
With a Mission to Make Mobile Free, Scratch W...
Scratch Wireless, claiming to be the world’s first truly free mobile service, has announced the availability of a new Scratch-enabled Android smartphone, the Coolpad Arise. The smartphone is equipped... Read more

Jobs Board

Payments Counsel, *Apple* Pay (mobile payme...
**Job Summary** Apple is looking for an atto ey to join Apple 's Legal Department to support Apple Pay. **Key Qualifications** 7+ years of relevant experience Read more
Touch Hardware Design and Integration Enginee...
…Summary** Design, develop, and launch next-generation Touch solutions in the new Apple Watch product category. The Touch team develops cutting-edge Touch solutions and 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* TV Live Streaming Frameworks Test En...
**Job Summary** Work and contribute towards the engineering of Apple 's state-of-the-art products involving video, audio, and graphics in Interactive Media Group (IMG) at Read more
*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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.