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

Evernote 6.13.1 - Create searchable note...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
Myriad 4.2.1 - Audio batch processor.
Myriad is, simply put, one of the best audio batch processors. Totally redesigned, it looks beautiful and delivers incredible performance. Let Myriad do the heavy lifting while you get back to doing... Read more
Garmin Express 5.8.0.0 - Manage your Gar...
Garmin Express is your essential tool for managing your Garmin devices. Update maps, golf courses and device software. You can even register your device. Update maps Update software Register your... Read more
Arq 5.10 - Online backup to Google Drive...
Arq is super-easy online backup for Mac and Windows computers. Back up to your own cloud account (Amazon Cloud Drive, Google Drive, Dropbox, OneDrive, Google Cloud Storage, any S3-compatible server... Read more
Garmin Express 5.8.0.0 - Manage your Gar...
Garmin Express is your essential tool for managing your Garmin devices. Update maps, golf courses and device software. You can even register your device. Update maps Update software Register your... Read more
Myriad 4.2.1 - Audio batch processor.
Myriad is, simply put, one of the best audio batch processors. Totally redesigned, it looks beautiful and delivers incredible performance. Let Myriad do the heavy lifting while you get back to doing... Read more
Arq 5.10 - Online backup to Google Drive...
Arq is super-easy online backup for Mac and Windows computers. Back up to your own cloud account (Amazon Cloud Drive, Google Drive, Dropbox, OneDrive, Google Cloud Storage, any S3-compatible server... Read more
Evernote 6.13.1 - Create searchable note...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
Parallels Desktop 13.2.0 - Run Windows a...
Parallels allows you to run Windows and Mac applications side by side. Choose your view to make Windows invisible while still using its applications, or keep the familiar Windows background and... Read more
jAlbum Pro 15.0 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more

Latest Forum Discussions

See All

The best mobile games to play during dre...
| Read more »
The mobile gamer's guide to Black F...
We're starting to catch wind of some exciting deals in the mobile gaming space for Black Friday. There are big discounts on mobile phones and accessories cropping up already, so you might want to get a move on things ahead of the big day. It's... | Read more »
The best pre-Black Friday deals - Novemb...
Black Friday will soon be upon us, but online retailers are already getting a headstart on the steep discounts. Don't wait until Friday—you'll find some pretty good deals all over the internet without waiting in lines or competing with other... | Read more »
Mighty Battles guide - how to build a so...
Mighty Battles, the latest title from Hothead Games, is set to take the App Store by storm. The game puts a welcome twist on lane battlers, adding FPS elements to spice things up a bit. You'll collect cards to put your own military unit to gether,... | Read more »
Rules of Survival guide - how to be the...
The PUBG craze makes its way to mobile, with more and more battle royale games debuting on iOS and Android. Rules of Survival joins the ranks of mobile PUBG-likes, offering a classic battle royale experiences that doesn't vary too much from its... | Read more »
The best new games we played this week -...
The weekend is upon us friends, and it's time to take a look back and reflect on all of the wonderful games we've played over the past few days. This week was jam packed with new releases. There were some big, long awaited launches, some fun... | Read more »
Lineage II: Revolution guide - tips and...
At long last, Lineage II: Revolution has now come to western shores, bring Netmarble's sweeping MMORPG to mobile devices. It's an addictive, epic experience, but some of the systems in the game can be a bit overwhelming. Here are a few tips to help... | Read more »
A Boy and His Blob (Games)
A Boy and His Blob 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Fight terrible monsters and collect epic...
Released on Western markets early last month, Dragon Project, created by Japanese developer COLOPL, brings epic monster hunting action to mobile for the very first time. Collect a huge array of weapons and armor, and join up with friends to fight... | Read more »
I Am The Hero (Games)
I Am The Hero 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: I Am The Hero is a pixel art, beat 'em up, fighting game that tells the story of a "Hero" with a glorious but mysterious past.... | Read more »

Price Scanner via MacPrices.net

Black Friday sale: Mac minis for $100 off MSR...
B&H Photo has Mac minis on sale for up to $100 off MSRP as part of their Black Friday sale, each including free shipping plus NY & NJ sales tax only: – 1.4GHz Mac mini: $399 $100 off MSRP – 2... Read more
Use your Apple Education discount to save up...
Purchase a new Mac using Apple’s Education discount, and take up to $300 off MSRP. All teachers, students, and staff of any educational institution with a .edu email address qualify for the discount... Read more
Adorama posts Black Friday deals on Apple Mac...
Adorama has posted Black Friday sale prices on many Macs, with MacBooks and iMacs available for up to $200 off MSRP. Shipping is free, and Adorama charges sales tax in NJ and NY only: MacBook Pros... Read more
Save up to $300 on 15″ 2.2GHz MacBook Pros
B&H Photo has the 15″ 2.2GHz MacBook Pro available for $200 off MSRP including free shipping plus NY & NJ sales tax only: – 15″ 2.2GHz MacBook Pro (MJLQ2LL/A): $1799 $200 off MSRP Amazon.com... Read more
Save up to $180 with Apple Certified Refurbis...
Apple has Certified Refurbished 2017 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB MacBook Air (... Read more
Black Friday deals on Apple Macs now live at...
Amazon has MacBook Pros, MacBook Airs, MacBooks, and iMacs on sale for up to $200 off MSRP for Black Friday week. Shipping is free. Note that stock of some Macs may come and go during the week, so... Read more
Black Friday pricing on Macs and iPads now av...
B&H Photo has lowered prices on many Macs, iPads, and iPad Pros as part of their Black Friday week sale. Save up to $200 on MacBooks and iMacs and up to $150 on iPads. B&H charges sales tax... Read more
Best Apple iPad deals this weekend, up to $80...
Apple resellers are offering 9.7″ iPads and 10.5″ iPad Pros for up to $80 off MSRP this weekend as part of their early Holiday and Black Friday sales: Adorama is offering new 2017 9.7″ 32GB WiFi... Read more
Early Black Friday sale: Apple iMacs for up t...
B&H Photo has 27-inch iMacs in stock and on sale for up $130-$150 off MSRP including free shipping. B&H charges sales tax in NY & NJ only: – 27″ 3.8GHz iMac (MNED2LL/A): $2149 $150 off... Read more
Apple restocks refurbished Mac minis starting...
Apple has restocked Certified Refurbished Mac minis starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: – 1.4GHz Mac mini: $419 $80 off MSRP – 2.6GHz Mac... Read more

Jobs Board

*Apple* Professional Learning Specialist - A...
# Apple Professional Learning Specialist Job Number: 112953711 Houston, Texas, United States Posted: 07-Sep-2017 Weekly Hours: 40.00 **Job Summary** The Apple Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Product Manager - *Apple* Pay on the *Appl...
Job Summary Apple is looking for a talented product manager to drive the expansion of Apple Pay on the Apple Online Store. This position includes a unique Read more
*Apple* Pro/Consumer Apps Support Engineer -...
…exemplify AppleCare's expert technical support paired with exceptional customer service for Apple 's software apps. This person is a problem solver, who understands Read more
Partner Marketing Manager, *Apple* Pay - Ap...
Job Summary The Apple Pay partner marketing team is looking for a Marketing Manager to develop and drive US programs. The right candidate will be passionate about Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.