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

Opera 44.0.2510.1449 - High-performance...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
Skim 1.4.29 - PDF reader and note-taker...
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim includes many features and has a... Read more
FontExplorer X Pro 6.0.2 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
1Password 6.7.1 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
Vivaldi 1.9.818.44 - An advanced browser...
Vivaldi is a browser for our friends. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind... Read more
Vivaldi 1.9.818.44 - An advanced browser...
Vivaldi is a browser for our friends. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind... Read more
Skim 1.4.29 - PDF reader and note-taker...
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim includes many features and has a... Read more
1Password 6.7.1 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
FontExplorer X Pro 6.0.2 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
VOX 2.8.24 - Music player that supports...
VOX just sounds better! 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 audio formats you should ever need.... Read more

Latest Forum Discussions

See All

Fire Emblem Heroes event announces new m...
As reported yesterday, Nintendo was gearing up a live press event for their popular mobile game,Fire Emblem Heroes. While the stream revealed a lot of new things, the event was entirely in Japanese. Luckily we have a rundown of what was announced... | Read more »
Best games we played this week
Another week, another slate of new mobile games. Although there weren't as many big name releases as last week, there were plenty of unique video game titles that came out that's sure to keep you interested over the weekend. Everything from classic... | Read more »
Olli by Tinrocket (Photography)
Olli by Tinrocket 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Get drawn in with Olli by TinrocketOlli instantly turns your everyday moments into hand-drawn art and animations. • Watch... | Read more »
Penarium (Games)
Penarium 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
Fire Emblem Heroes is way more profitabl...
Profits for Nintendo's mobile game Fire Emblem Heroes are apparently impressive enough to beat out other Nintendo titles likeSuper Mario Run, despite having 10 times fewer downloads. [Read more] | Read more »
Classic series Robot Unicorn Attack 3 no...
The classic Adult Swim browser game, Robot Unicorn Attack, branched off into a series of popular mobile games. Now, the latest entry into the series, Robot Unicorn Attack 3, is available for iOS and Android mobile devices. [Read more] | Read more »
Sudoku Sweeper (Games)
Sudoku Sweeper 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: A minimalist mashup of Minesweeper and Sudoku. Logic puzzle perfection. Every row, column and zone contains a bomb and one of... | Read more »
Under Leaves (Games)
Under Leaves 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Journey into the forest, the jungle or the depths of the deep blue sea. Find chestnuts for the pigs, a caterpillar for the... | Read more »
Ninja Pizza Girl (Games)
Ninja Pizza Girl 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: In the not-so-distant future, rampart traffic congestion has resulted in only one way to deliver pizzas across town in thirty... | Read more »
SCRAP (Games)
SCRAP 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: That day, for no apparent reason, SCRAP decided to wake up and run. He had to, because his activation was a mistake the "Factory" could... | Read more »

Price Scanner via MacPrices.net

15-inch 2.7GHz Space Gray Touch Bar MacBook P...
B&H Photo has the 15″ 2.7GHz Space Gray Touch Bar MacBook Pro in stock today and on sale for $2599…$200 off MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 15″ 2.7GHz... Read more
13-inch 2.9GHz/256GB Space Gray Touch Bar Mac...
B&H Photo has the 13″ 2.9GHz/256GB Space Gray Touch Bar MacBook Pro in stock today and on sale for $150 off MSRP including free shipping plus NY & NJ sales tax only: - 13″ 2.9GHz/256GB Touch... Read more
21-inch iMacs on sale for up to $151 off MSRP
B&H Photo has 21″ iMacs on sale for up to $151 off MSRP, each including free shipping plus NY sales tax only: - 21″ 3.1GHz iMac 4K: $1348 $151 off MSRP - 21″ 2.8GHz iMac: $1199.99 $100 off MSRP... Read more
Weekend deal: Up to $420 off new MacBook Pros...
Apple has Certified Refurbished 2016 15″ and 13″ MacBook Pros available for $230 to $420 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2.6GHz... Read more
Price drop: 15-inch 2.2GHz Retina MacBook Pro...
Amazon has dropped their price on 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) to $1709.99 including free shipping. Their price is $290 off MSRP for this model. Note that stock may sell out quickly at... Read more
2.8GHz Mac mini on sale for $899, save $100
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Check Apple prices on any device with the iTr...
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
New System Clock for macOS by B-Eng Now Avail...
Fehraltorf, Switzerland based B-Eng has announced the release and immediate availability of System Clock, the company’s new system monitor and information app developed exclusively for macOS. System... Read more
DEVONtechnologies Celebrates 15th Anniversary...
DEVONtechnologies celebrates its 15th company anniversary with a 30% discount on all its software products from May 1st through 5th, 2017. In spring 2002, DEVONtechnologies opened its website and... Read more
WaterField Designs Invites Customers to Help...
San Francisco based WaterField Designs invites customers and air travelers to participate in developing the next generation in-flight travel case, the Air Porter. Frustrated with limited legroom,... Read more

Jobs Board

Best Buy *Apple* Computing Master - Best Bu...
**501846BR** **Job Title:** Best Buy Apple Computing Master **Location Number:** 001126-South Bay Center-Store **Job Description:** **What does a Best Buy Apple Read more
Consultant or Sr. Consultant, *Apple* Allia...
…improve our business and your clients will be heard.Project Manager, Apple AllianceLocation:San Francisco preferred, open to other locationsLevel:Consultant or Sr. Read more
*Apple* Mac Computer Technician - GeekHampto...
…complex computer issues over the phone and in person? GeekHampton, Long Island's Apple Premium Service Provider, is looking for you! Come work with our crew Read more
*Apple* Mobile Master - Best Buy (United Sta...
**501505BR** **Job Title:** Apple Mobile Master **Location Number:** 000849-Gurnee-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** At Read more
Best Buy *Apple* Computing Master - Best Bu...
**498428BR** **Job Title:** Best Buy Apple Computing Master **Location Number:** 000293-Rockville-Store **Job Description:** **What does a Best Buy Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.