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The Floppy Disk Drive Engineering Design Challenge SSD to FDD

The challenge is to design a floppy disk drive interface to be a direct replacement for 3½-inch FDD or older 5¼-inch floppy disk drives on legacy industrial computer equipment. The FDD engineering hardware design requirements would be to build a new style FDD solid state disk drive, hooked up on the floppy disk connector (FDD). [...]

Click to read more about: The Floppy Disk Drive Engineering Design Challenge SSD to FDD

The challenge is to design a floppy disk drive interface to be a direct replacement for 3½-inch FDD or older 5¼-inch floppy disk drives on legacy industrial computer equipment. The FDD engineering hardware design requirements would be to build a new style FDD solid state disk drive, hooked up on the floppy disk connector (FDD). Keep in mind, the option to install is not available on legacy machines a solid state HD device — IDE to Compact Flash CF adapter on the parallel IDE HD connector since many industrial equipment machines do not support IDE; which by-the-way, these direct replacement hard drive adapters are currently available for PCs with IDE PATA ports (see images below). As part of the engineering guidelines, the direct replacement FDD device must also be able to read and write from FDD 1 to Solid State CF FDD 2 or vice versa. Additional followup information to this FDD article can be found at: FDD Floppy Disk Drive Emulators and Interfaces

View solid state hard drive adapters for compact flash memory cards displayed below.

FDD Engineering and Design Notes For Direct Replacement Floppy Drives

Message: “Jim: I have been searching for a replacement for a 3.5″ FDD that reads/writes to a USB flashdrive or CF memory card.

Has the Engineering Challenge generated any solutions, yet?

I’m hoping ….



Hello M,

I’ve gotten a bit of feedback in this area.

Apparently the signal conversion is a bit more difficult than meets the eye. I have spoken with some engineers that have a cursory understanding of the floppy disk system, but it seems the interface is more complicated than the HD solid state disk drive to an IDE port. This seems strange that a simple device (in concept) like this is not available. I would think there is an engineer out there that could do this, but so far haven’t heard from anyone that can do it.

Some people have a hard time understanding what it is being requested here.

They want to tell me that there are already external USB floppy drives. I have to tell them that is not what we need. We need a direct plug in to the FDD cable that reads/writes to a USB flashdrive or CF memory card.

Maybe I need to spell it out a little more concisely.

Email Jim today.

Many of the old industrial machines used in various product manufacturing industries, and continued to be serviced and supported throughout the manufacturing world today, especially that of the circuit board drilling equipment and PCB routing machines, along with legacy CNC metal fabrication and CNC plastic machining, mold cutting equipment, and die making machines still use either the 5¼ FDD or 3.5 inch FDD to load operating systems and store part programs on hybrid computers. These hybrid computers are not PC based and have no internal or external hard disk drives, nor are these industrial equipment machines capable of hooking up a hard disk drive through any type of IDE cable connector; since the computers do not have IDE HDD interface capabilities, nor do they have USB connector capabilities either. Other machine fields that are excellent candidates for a new style SDD FDD would include: commercial grade and high-end consumer models embroidery machine equipment, quilting machines, and programmable sewing machines used built-in floppy drives for storing patterns and job programs.

Other industrial machines were designed around the original IBM PC which preceded the “IBM XT” and included 5 ¼ inch floppy drives but no hard disk. There may not be very many of these types of machines still in existence or actively used in production today.

Machines that are still being used in production, but have their own hybrid computers, are typically using a proprietary floppy disk controller for reading and writing to the floppy disk drives. This makes disks written in the proprietary format, unable to be read with the standard PC format floppy drives.

New manufacturing equipment is very expensive. Many of these these older machines are still quite capable of producing products in a production environment, and their owners are not willing to throw them away to buy a brand new machine equipment that will produce the same amount of product, in the same amount of time.

History of the Floppy Disk Drive

Floppy drives have been around since 1971, when IBM was the first to introduce the 80 KB read-only 8-inch FD. Subsequently, IBM, Memorex, and Shugart introduced 8-inch RW SSSD and DSSD floppy drives that reached a storage capacity of 980 KB (CP/M) – 1.2 MB (MS-DOS FAT) in 1977. Then in 1978 the 5¼-inch DD was introduced which had a storage capacity of 360 KB or 800 KB. In 1982 the first 3½-inch HP single sided FDD came on the market with a capacity of 264 KB. 1984 marked the introduction of the Macintosh which used the 3½-inch (DD at release). It had a marked capacity of 1 MB, though it was more like 720 KB (400 KB SS, 800 KB DS on Macintosh, and 880 KB DS on the Amiga computer).

3½-inch and 5¼-inch floppy drives shared the market place from 1982 through the late 1990s and even some industrial equipment manufacturers continued to use 5¼-inch floppy drives just at the turn of the century, though most industrial equipment manufacturers switched to the 3½-inch FDD models long before. The floppy disk drives have now been largely superseded by USB flash drives, CD-ROMs and DVD-ROMs.

R&D and Investment Capital by US Industrial Equipment Manufacturers

How did we get into this FDD mess. Part of the reluctance for US industrial equipment manufacturers to design new industrial equipment, with using new style PC based controllers had to do with the costs associated with R&D investments in both hardware and software engineering and design. Also, because of the sizeable R&D investments which many of these companies had made in the past, with specialized dedicated computers that had worked well up until this time in a manufacturing environment, top management was reluctant to spend any more investment capital into designing what was already perceived as a solid engineering design. While US companies sat on their laurels, their foreign manufacturing counterparts had leapfrogged over the controller designs, and started building controllers that were using standard, over the counter, PC based controllers, with software written to run under a Microsoft Windows environment. Now, many of the US manufacturers have been hit hard by the foreign competition and are struggling mightily to compete once again in the world markets.

What we need, is a Floppy Disk Drive Solid State Bridge or FDD SSD

What is happening for many of the end users of this legacy equipment is simply that the floppy drives are wearing out. They are getting old, and with the lack of replacement parts available, the equipment is becoming obsolete. These end users need a floppy disk drive bridge to get them over the hump, especially in these difficult economic times. They need something cheap and easy, that would quickly interface to these old floppy disk drives with a simple FDD plug and play device that requires no software drivers to be installed on the computer. Ideally speaking, it would be based on the solid state drive design similar to the SDD HDD — solid state drive hard disk drive, but for a SDD FDD — solid state drive floppy disk drive hookup.

The demise of the floppy disk drive is making it more difficult to keep aging computer systems operational. Floppies are still used for emergency boot disks on many of these aging systems that lack support for other boot media such as CD-ROMs and USB devices. Even some of the Windows Operating systems such as Windows XP and Windows Server 2003 relied on third party drivers, loaded on floppies. Many of the BIOS and firmware update and restore programs require they be executed from a bootable floppy disk. And if heaven forbid, during a BIOS update something goes wrong, even as of 2008, a floppy disk is required to perform a BIOS recovery after a failed BIOS update attempt.

The music industry still employs many types of electronic equipment that use standard floppy disks as a storage medium. Equipment that is quite functional, and was quite expensive to purchase, and would undoubtedly be prohibitively expensive to replace such items in the music industry as: synthesizers, samplers, drum machines, and sequencers, all of which continue to use 3½-inch floppy disks. Other storage options, such as CD-R, CD-RW, network connections, and USB storage devices have taken much longer to mature in this industry. Source: Wikipedia — Floppy Disk Drive.

So, it makes sense to bridge the FDD storage technology gap between the old floppies and the newer storage device options of CDs, DVDs, external HDs, and USB storage devices.

SSD HDD — Solid State Disk Drives For Laptops, Notebooks, and PC & Apple Desktop Computers

Here are some examples of HDD solid state hard drive adapter devices that can be used on computers to replace the internal hard disk drives using an adapter plug and socket to install Compact Flash (CF). Besides the availability of hard drive adapters, a person can replace their internal hard drive with solid state drives. There are SSD HD IDE PATA for the older parallel ATA interface IDE internal hard drives and SSD HD SATA for the newer and faster serial ATA interfaces available too.

Floppy Disk Drive Bay Mounts and PCI Slot for IDE to Compact Flash Adapter

Addonics Technoloigies, located in the Silicon Valley, California, manufactures many types of adapters designed to be direct replacement devices for hard disk drives. Addonics offers a full range of storage devices based on various storage technologies – optical (CD, DVD, CDRW, DVD-R/RW), hard disk (3.5″, 2.5″, 1.8″ and Micro Drive), floppy, small digital media reader/writer and stand alone storage appliances. Most of Addonics products are designed to connect to different interface technologies – USB, Firewire, Serial ATA, CardBus, SCSI, IDE and all Windows operating systems. Some devices also have been certified to work under Linux, Mac and Solaris 8. Together with a set of complementary accessories – power cables, host controllers and adapters, Addonics products have been selected to deploy in various vertical markets and applications, including in some mission critical environments. Read more about Addonics’ storage solutions.

Many of their products are used to create your own storage size solid state HDD using Compact Flash card sizes of your choice and embed the devices in laptop and notebook computers’ HDD cavities. The item pictured above provides two slots to include both a master and slave HDD Solid State CF drive built into one compact unit. Single slot CF Hard Drive Adapters are available too. With the price of Compact Flash Memory dropping, it is very easy to see how this IDE HDD adapter to Solid State HDD could be utilized in both old and new notebook computers. To replace the internal laptop HDD drive requires simply removing the old 2.5” IDE hard drive from the 44 pin IDE connector and attach the CF adapter with the CF card inserted onto the 44 pin IDE connector with key pins matching. Then you simply tuck it away inside the old hard disk drive bay cavity with double faced tape. Read the details for this device, along with detailed illustration about replacing the hard drive with the Addonics CF HDD Adapter in a notebook or laptop computer. Adapters like this and others for the newer serial interfaces would be an excellent choice for both Apple laptops as well as any of the older PC laptops with either Microsoft Windows or Linux based operating systems.

A while back, I had the pleasure of speaking with a sales engineer at Addonics about the need for a FDD solid state replacement device. He was most helpful, but at that time, Addonics did not have anything available in the way of an adapter to go from floppy disk drives to compact flash or any other form of solid state storage. While he did mention that others had also contacted him over the years to design this type of device, he felt it would be expensive to develop the FDD solid state interface device for what was perceived as not having a very large demand for the product.

External Floppy using USB Interface

In recent years, because many of the computer manufacturers were not installing floppy disk drives into new computers, has brought about a need for an external floppy disk drive. Behold the USB plug and play Floppy Disk Drive.

A0769810 Before we get to the USB Floppy Disk Drive product, there was however a plug-in module device available from Dell Computers in the UK that plugged directly into the IDE interface cable from a motherboard to a 1.4 MB Floppy Disk Drive. The manufacturer was Origin Storage, with the manufacturer’s part number being listed as: CSERIES/FDD, and the Dell part number listed as: A0769810. Not sure if this floppy disk drive adapter hookup to an IDE parallel hard drive port is still available, or who would really need or be interested in this FDD to IDE port device today, but I thought it might be interesting to note it in this article. Also note that I was not able to find that particular FDD IDE device on Dell’s US website. Maybe it is an old out-dated link on Dell’s UK website. Like I said, I’m not sure there really is a need for this device. I don’t think we need to place floppy disk drives at the end of IDE cables, but it sure would be nice to store old system software from a floppy disk on legacy, non PC based and no IDE based machines, and boot to a solid state CF adapter on the FDD cable. Let’s build a solid state floppy disk drive as a direct replacement for a FDD.

USB Floppy Disk Drives — External USB Floppy Disk Drives

Some have asked, “why not just install a USB floppy disk drive on this old equipment?” Well, the biggest hurdle with this solution idea, is old non-PC based computers do not have the option for USB interfaces. Yes, you could install an external USB FDD drive on any PC that provided for USB devices to be installed, though there are generally Microsoft Windows software requirements for hooking up most of these external USB 3.5 inch floppy disk drives.

Others have even come up with a brainstorm of a solution of having some sort of Floppy Disk Drive to USB interface. In essence, this would involve going from the FDD cable into some sort of USB storage device. That might be a possible solution, but one would have to engineer an interface to go from the floppy pin-outs and reading and writing electronic signals requirements of the floppy disk drives, to a USB interface device that was a stand-alone, no drivers required plug-in adapter unit.

Sony Floppy Disk Adapter Sony developed the Memory Stick/Floppy Disk Adapter MSAC-FD2M. The MSAC-FD2M adapter was specifically created for the Sony Mavica FD-95 camera. SanDisk, SmartDisk, and Dane manufactured the FlashPath Floppy Drive Card Adapter for Smartmedia memory cards. These floppy disk adapters provided a slot in the edge of a floppy disk looking unit that Smartmedia cards could be inserted and then insert the whole 3.5 inch adapter into the camera or into a 3.5 inch floppy disk drive in a PC. The application was for those computers that did not have a built-in USB port, to be able to read the Smartmedia memory cards into the PC. With the addition of USB support in newer computers, these floppy disk adapters quickly faded off the landscape though you can still find them available in some online locations.

So that gives an overview of what is available for floppy disk drives, adapters, memory cards, and solid state disk drives.

FDD to USB Emulator Engineering and Design Project

On April 2008, Google Groups section, Jim F. wrote about his venture into building a floppy drive interface and the information he is seeking.

I’ve decided on a new project (this is for fun only) where I will build my own USB thumb drive to floppy interface. My intention is to replace the single floppy drive that exists in a particular piece of legacy test equipment. This will need to be a complete hardware solution (cpld/ucontroller) interface which I can remove the floppy and replace it with my USB floppy emulator.

I’ve really never given floppy technology much thought, so I figured it would be fun to go back to the 80′s and get acquainted with it…

I’ve been searching the web but haven’t had any real luck finding *good* technical data on floppy drive electrical interface data. I’ve read a few floppy drive specification data sheets, but they seem a bit lacking. Does anyone know of a really good repository for this information?

Thanks for any help that you can offer…


This is quite an interesting thread into building the floppy interface by creating a USB thumb drive to a FDD interface. Read more at sci.electronics design. I’m not sure what the status of his engineering design is currently, but it sounded like others would certainly like to see a device like this too. In the thread you will find more technical information into the engineering and design of this FDD interface project. If anyone has any further information into this FDD adapter interface project, please post your comments here or at the Google Groups Science Electronics Design posting. Considering the reduction in the cost of USB Flash Drives, this might very well be a viable solution for the FDD adapter project.

Read the second segment FDD interface article titled: FDD Flopyy Disk Drive Emulators and Interfaces.

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Apple iMac G5 Power Supply Issues and DIY Apple Repairs

Please help bring my beautiful Apple G5 back to life. High quality, low ESR, capacitors for sale, or match iMac PSU model type you have to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards. Are you having problems with [...]

Click to read more about: Apple iMac G5 Power Supply Issues and DIY Apple Repairs

Please help bring my beautiful Apple G5 back to life.

High quality, low ESR, capacitors for sale, or match iMac PSU model type you have to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards.

Apple Capacitors For Sale - Click Here

Are you having problems with your Apple iMac G5 17 and 20 inch consumer, university, or student models? Does your iMac turn off by itself? Are you seeing strange graphics on the video screen? Is it to the point where it doesn’t even turn on anymore? Is it running hot and the fans sound like a vacuum cleaner?

Well folks, here is one of the problems with many of the Apple power supplies manufactured for their iMac G5, 17 and 20 inch series computers. But fear not, I have put a “How to Fix Series” together on how to fix an iMac G5 power supply and mother board. Power supply information is located right here in this article. I would also suggest reading the latest article on Fat Caps and Ripple Current to have a better understanding of what is happening with Bad Caps inside these Apple iMac G5 power supplies and logic cards.

Also, you can read and see how to fix the G5 mother board over here.

If your Apple iMac G5 power supply doesn’t match up exactly to what you see pictured below, feel free to send me your pictures (inside and outside of the iMac MOBs and PSUs). I also have provided additional pictures for comparing which PSU capacitor kits are available for the various power supplies over at “Inside the Apple iMac“. You can also click the buy now buttons to purchase the power supply kits.

As a side note, if you need to get the data quickly (pictures, files, and programs) off the HD for your old Mac, and place it on your HD on the new Mac, read about the Apple iMac G5 Hard Drive Data Recovery. It is designed for those that want to recover the information from their hard drives on a dead PC or Mac. This HD device works really great for Apple iMac backups too!

Apple iMac G5 Power Supply 17 Inch Model

Apple iMac G5 Power Supply 17 Inch Model
180W – Apple P/N 614-0293

Figure #1

Updated 9/12/09: High Quality Low ESR capacitors, computer motherboard grade, 105ºC, 10mm X 16mm, now available for sale in kit form for the Apple iMac G5 computer MOBs and the PSUs.

The capacitor sizes, included in the MOB kits, are the actual original sizes of the capacitors on the motherboard; making your job much easier to replace them. They are the perfect fit for both diameter and height. Note: The PSU cap kits have been upgraded.

International shipping is available for many countries. If your country isn’t listed for a shipping destination, please let me know to add your country to the list. Please provide your full name (first and last name) when ordering capacitors. Read the Shipping for shipping and delivery information.

If you are interested in more than 10 MOB cap kits, please send me an email with a total amount of how many iMac G5 cap kits you are looking for, along with a note of which of the two different cap kit sets you are interested in. Note: Apple early model and late model iMac G5s with the PowerPC processor have different quantities of caps required on the MOB. Click the eCommerce link. Capacitor information is provided there. Verify what capacitors your Apple iMac needs, and bring your iMac G5 back to life today.

Send me an email with your questions, or special order requests. I now have all the power supply cap kits available. Feel free to contact me any time, with any questions. Take a look at the PSU cap kits that are available for purchase.

Just a brief update for those that have been out of the capacitor loop. About the time Apple was building their G5 line of personal computers, several Taiwanese electrolyte manufacturers began using a stolen electrolyte formula that was incomplete, and lacked key ingredients needed to produce a stable capacitor. The missing ingredients caused the electrolyte in the capacitors to break down, evaporate, leak out of the cap casings, caused overheating of the capacitors themselves under normal load conditions, and subsequently caused exploding poppers. Consequently the capacitors started bulging, overheating, and exploding in many of the power supplies and mother boards manufactured by Apple, Dell, Hewlett-Packard, and others which has been documented by numerous articles online. In fact, Dell took a “$300 million financial charge on its earnings to cover costs associated with the replacement of motherboards with faulty capacitors in some of its Optiplex workstations” in late 2005 early 2006. For those of you that are interested, I have documented a do-it-yourself repair procedure and an educational information manual on the Apple iMac G5 motherboards along with students’ user comments.

Note: Apple provided an iMac G5 Repair Extension Program for Video and Power Issues: See the frequently asked questions section at Apple about which models and serial numbers are/were covered. Howeve
r, in all likelihood (“As of December 15, 2008, this program is now closed.”), the iMac G5 Repair Extension Program has run out its course for most, if not all iMac G5 PowerPC owners. See Apple information on the power supply and the video and power issues documents. You can read the actual repair extension program text in the Apple iMac Mother Board article, exactly as it was in the original Apple documents. The program was available for certain iMac G5 PowerPC models that were sold between approximately September 2004 and June 2005 featuring 17-inch and 20-inch displays with 1.6GHz and 1.8GHz G5 processors. You may also go to any Apple Retail Store with a Genus Bar and have the Apple folks take a look at your iMac for you. Find the nearest Apple Retail Store – Genius Bar in your area, and even make an Genius Bar appointment online too. Apple provides technical support for your Mac, iPod, Apple TV, and iPhone at the Genius Bar too.

Identifying the Apple iMac Power Supply Problem or iMac G5 Motherboard Problem

Apple provides a diagnostic guide for determining whether the problem is with the motherboard or the power supply. See the following link to the: iMac G5: Troubleshooting when your computer won’t turn on. Included in that Apple document are instructions of how to turn on an iMac with the back cover off. There are two small buttons located under the fan cover as displayed in the document. One button is the internal power button, and the other button is for resetting the System Management Unit (SMU) which is located right next to the internal power button. “Note: If you’re using an iMac G5 (Ambient Light Sensor) computer, your SMU was already reset when you unplugged and replugged the computer. You won’t see an SMU reset button to press, and that’s OK, as this action has already been done. (If you aren’t sure which iMac G5 model you have, click here for help.)” Source: Apple

Since, I feel that I have been somewhat of an online trailblazer on documenting the iMac issues and the Apple iMac G5 motherboard repairs project, I thought I would take the time to dive into another area that many of our readers have stated is also a big problem with the Apple G5 line of computers. That big issue has to do with the main power supply installed in the iMacs are dying and dropping like flies. From what I understand (though not confirmed) about the iMac PSUs, is there are at least several different power supplies used by Apple in their iMac G5 model lines. The part numbers are located on the back of the PSU case. This power supply is Apple P/N 614-0293 Rev. A 180W. The serial number has a barcode graph. The various models associated with this particular DIY repair document are for Apple: iMac G5 (20-Inch), iMac G5 (20-Inch iSight), iMac G5 (17-Inch), iMac G5 (17-Inch iSight), iMac G5 ALS (17-Inch), and iMac G5 ALS (20-Inch) consumer, university, and student models. See the Apple Power Supply, 17-inch Replacement Instructions for how to remove and install your power supply unit. If you have an Apple model with the ambient light sensor, pay particular attention to not breaking the wiring or the sensor that is mounted to the lower portion of the power supply when removing the PSU. Ok, that gets your power supply unit out. Now what?

There are several service repair or replacement options available for your iMac G5 power supply.

  1. Order a new power supply from Apple Parts & Services.
  2. Order a new PSU, rebuilt power supply, or have your PSU repaired from an outside source.
  3. Repair the power supply unit yourself.

Before I talk about option number three, I would like to point out that when you buy a used or new power supply from Apple or another vendor, you have no idea whether the capacitors that are used in this new or used PS are any better than the ones that were installed in your particular iMac. In all likelihood, the new or rebuilt PSU might not last either. I have heard stories of Apple Service replacing a person’s iMac power supply, and several months later having to do it again. With that being said, it seems obvious that you are taking a chance no matter what you do. By-the-way, the cost of a power supply for an iMac will likely set you back 150 to 200 buckaroos. To me, $150.00 or $200.00 seems like an awful lot of money to shell out for such a small power supply that might not last more than a few months. Capacitors actually get old just sitting on the shelf.


Apple iMac G5 17 Inch Model

Apple iMac G5 17 Inch
Figure #2

With many of my readers sharing their iMac G5 stories, both in the online comments section and sending emails to me documenting their problems they are having with their Apple iMacs, I thought it was prudent to take the next step and see if I could discover first hand what was going on in the field with these 17 inch iMacs. I already own an Apple iMac 20 inch model but I needed a 17 inch one for further investigative work. So, I went searching for a broken iMac G5 computer that I could get my hands on for a fair price. I didn’t want to spend a ton of money on a broken Apple to do my research, but I needed to do some more engineering and technical failure analysis of the problems of iMacs not turning on because of mother board problems or a power supply situation. Many people kept telling me that they had an iMac G5 17 inch model computer with no physical signs of bad capacitors on the motherboard. I wanted to verify this for myself. I found an iMac G5 17 inch on Craigslist from a guy that felt he got ripped off by someone selling a supposedly good working iMac to him a short time back and then when he plugged it in, it didn’t work. He took it to the local Apple Genius Bar folks and they said he needed a new motherboard. So, after talking with the seller and asking him some questions about this particular iMac, we settled on a fair price, I met him in San Ramon, CA, and purchased it from him. In my opinion he was a straight shooter, and was nice enough to allow me to open the back cover up before I purchased it in order to make sure all the hardware was inside, i.e., hard drive, motherboard, power supply, fans, memory, cd/dvd SuperDrive. However, he had given away the keyboard, mouse, and the software to some friends. Oh well, keyboards and mice are not very expensive, and if I need Mac OS X software, I can purchase that too.

So, I get my new, broken, what an oxymoron, iMac G5 back to the office and I plug it in, push the power button, and it just sits there staring at me with a blank screen. Nothing powers up. Dead in the water. Dead on arrival. DOA, just what I wanted. Really! Yes, it was time to go to start my engineering class work. I opened the back of the computer once again and took a much closer inspection of the motherboard and the capacitors. Believe it or not, all the capacitors look good on the MOB, just like some of my readers have documented with their own stories in written emails I received from them. This is a completely different issue than what I saw on my iMac G5 20 inch motherboard problem with the bad capacitors on the MOB, with some caps just about ready to pop. All the capacitors on this motherboard looked completely intact, with no signs of swelling, bulging, or electrolytic juice leaking out anywhere to be seen on this 17 inch model.

The next step in my troubleshooting analysis probe was to remove the power supply and do the smell test. Yes, use your other senses other than eyesight when troubleshooting electronics or checking out other industrial equipment. The smell of burnt electronic components can sometimes be detected months and years later, even after a burnt component has been replaced. I placed the power supply up to my nose, and I thought I got a slight whiff of that unforgettable smell of burnt electronic components. Now, it was time for the 20/20 vision eyesight test.

Danger High Voltage Electrical Shock Warning!

This information is provided as a safety precaution and to be careful. A warning at this next stage of the technical analysis is warranted. Electronics, and power supplies in general have high power electronic circuits which can cause a body harm if you touch the wrong thing, even if unplugged. First off, make sure your power supply is not plugged into the AC power outlet. Note also that power supplies typically have a primary high voltage input side and a secondary low voltage(s) output side. The high voltage input side can have large filtering capacitors which can store an electrical charge (DC voltage potential) for a long time, even after a power supply is unplugged from the AC power outlet. Take the precautionary step, and discharge these primary capacitors (after it is unplugged from the AC power) with a screwdriver or place jumper wires across the leads prior to working on the PSU printed circuit board. If you have a different type of supply than what is shown here, with large cylinder capacitors standing up on the primary side, you will not be able to get to the leads on the bottom of the circuit board in order to discharge them. However, if a power supply is left off, unplugged for a period of time; certainly if it has been off and unplugged for an hour or two, the majority of the charge will have dissipated from the capacitors due to in circuit resistance and time.

The iMac G5 PSU case design, is one by which Apple’s engineers designed their power supply units with security torx fasteners (screws) attaching the metal cover housing to prevent unauthorized disassembly, and also I am sure to prevent anyone from getting hurt. I do not own one of these security torx drivers, as I suspect most people can say they don’t have one in their tool box either. I was having an email conversation over the past week with a physics professor at a university. He mentioned he has ten 1.6GHz 17″ G5 iMacs at the university, four of which have already collapsed completely. He was also the first to mention to me, about the security torx key being required to open the PS cases.

In this case no problem on the mother board, but big trouble in the power supply (lots of caps in trouble, one totally blown). One can see some of them through the power supply case, so you might want to take a look at yours.

Be careful of the two high capacity capacitors in the unit, they can be lethal. Ph.D., ARCS

I was able to unscrew the torx screws using a precision miniature screwdriver, and broke out the small internal security tabs within the head of the torx screws themselves. Once I did that, the torx screws were relatively easy to remove.

Pictured Below Are The Electronic Components and Printed Circuit Board Completely Removed From The Power Supply Unit

Apple iMac G5 PSU Capacitors Locations

Capacitors’ Locations, Sizes, and Electrical Values For Apple iMac G5 Power Supply Unit Diagram Schematic.
Click image for close up view of G5 PSU capacitors.
Figure #3

Here’s a confirmed list of the secondary (low voltage) side PSU capacitors installed in the iMac G5 17 inch model. It maybe different on the iMac G5 20 inch, ALS, and iSight models. Please send me an email confirmation or comment on the iSight models, iMac G5 20 inch models, and ALS (Automatic Light Sensor) models, along with any capacitor sizes, quantities, and values would be much appreciated. Please include the Apple p/n and the last four digits of the Apple EEE Code (The last four digits on the serial number). See Cap Note:

  • 3x- 1000uf 6.3V 8mm x 16mm
  • 2x- 2200uf 10V 10mm x 24mm
  • 1x- 1200uf 16V 10mm x 24mm
  • 1x- 4700uf 6.3V 10mm x 30mm
  • 1x- 1000uf 35V 12.5mm x 20mm
  • 1x- 330uf 35V 10mm x 20mm

What you are looking at in figure #3, once you remove the cover of the PSU, are signs of bad capacitors all over the printed circuit board. The first image (Figure #1) above shows the blown capacitor, burnt on the top, and burnt residue on the cover too. If you look closely at Figure #3 and Figure #4, you can see telltale signs of capacitors that are bulging and getting ready to blow their tops. Note the gray silicon rubber adhesive that has been squeezed into and between the electronic components on the circuit board. Some believe that this goop was used for anti-vibration and noise dampening as can be seen with the application of a small amount of goop on a potentiometer adjustment located in the top middle of the PCB, next to the transformers. I can understand the use of it to hold the large primary capacitors in place. However, in my opinion, I believe this was an attempt by the manufacturer (Apple) to make it more difficult to repair the PSUs when using it so liberally throughout the entire PSU. If however, I am wrong, and this is not the case, and the designer intended this goop to be used for anti-vibration noise dampening purposes, the assemblers seem to have gone overboard on their use of it, and it has had an unintended consequence of heat build up. If you look closely at the tall boy cap, I think this one ended up sandwiched in an oven, right next to the coil choke (see closeup picture on Figure #4). In my opinion, it’s not like the small capacitors are going to move once they are soldered in place. It’s also likely that this silicon rubber filler was instrumental in the early failure of the other capacitors too. Excessive heat buildup likely resulted from the insulating characteristics of silicon rubber encapsulation which would result in a runaway thermal chain reaction and cooked the components. Cool air circulation was none existent in these encapsulated areas of the PSU. This silicon adhesive must be gingerly picked at and cut away, in order to get proper access to all the bad capacitors, and be able to remove them when they are unsoldered from the PCB.

Directly below in Figure #4 is a slightly angled picture view, with a closeup of the capacitors on the iMac G5 Power Supply printed circuit board in view and most of the silicon rubber goop removed.

Closeup View iMac G5 Power Supply Printed Circuit Board

Closeup View of Apple iMac G5 Power Supply Printed Circuit Board With Bad Capacitors
Click image for an even closer view of the PCB and PSU capacitors.
Figure #4

The tools I used on the PCB for cutting and picking away at the silicon adhesive are on display in Figure #4 too. I used by trusty precision miniature screwdriver (Husky model HD-74501 S “a gift”) with multiple bits in the handle, which came in handy for removing the torx fasteners and picking away at the small sections of silicon adhesive, the small retractable utility knife box cutter was used to cut away the big gobs of silicon rubber, and the inch/metric 6 inch scale was used for measuring the capacitor physical sizes.

So, the bottom line is most of the secondary low voltage side capacitors must be replaced on this particular G5 PSU. I will probably replace them all. Some of the capacitors I am told are difficult to find. This is especially true of some of the smaller diameter capacitors. Spaces are limited on the PCB. Also, note the one 350 microfarad 35 volt 10mm x 20mm capacitor (Figure #4 with close up view) that is located under the copper heat sink in the middle of the PCB. This is going to be most certainly problematic for capacitor replacement, since it is most likely that I will have to remove the 1000 microfarad cap in front of this 350uf capacitor in order to slide it out from underneath the heat sink assembly. The heat sink assembly is mounted to what appears to be voltage regulators that are impossible to remove without first removing other inductor choke coils, capacitors, and other components in front of the heat sink assembly.

Surface Mount Technology SMT SMC SMD
Surface Mount Technology – SMT
Surface Mount Components – SMC
Surface Mount Devices – SMD
Figure #5

A word of caution about the bottom surface of the PCB before you proceed with on-board capacitor replacements. Be careful not to damage any of the SMC, Surface Mount Components (Figure #5 pictured on the right) located on the bottom of the printed circuit board. These discrete SMT, Surface Mount Technology micro components are very small (some of the SMD, Surface Mount Devices, are hard to see with the naked eye) and consist of SMC diodes, SMC resistors, SMC capacitors, SMC transistors, and SMC IC chips in close proximity to where the large electrolytic capacitor leads protrude through the bottom and are soldered to the plated through holes of the PCB. Be extremely careful when soldering next to these SMDs. If you heat up a SMD by accident with the soldering iron, (see lead-free soldering tips for more soldering information) you will potentially dislodge it from its PCB pad. Figure #3 shows the PCB top side surface before picture, with all the silicon rubber adhesive stuck between the electronic components. Figure #4 picture is after the silicon rubber, for the most part, has been removed from the components on the secondary side of the PSU.

Now, the next step in the process is to purchase the nine electrolytic, radial leads, low ESR capacitors designed for tight spaces. For most folks out there in Internet land, I realize there probably is much technical information to digest here in one quick reading. I feel like I have written and photographed a technical documentary. I will most likely publish an updated technical article or add to this document when I locate new capacitors and proceed with the the installation of these new low ESR electrolytic capacitors. Cap Note: I suspect I will have some different suggested sizes to use for cap substitutes. You are free to print out this document using the “print button” for your personal use, but you are not granted permission to distribute or publish it anywhere else without my prior approval. That goes ditto for all the articles published on this website too.

All information provided here is for instructional purposes only. Please note that I cannot be held responsible for any damage that you might do to your computer or yourself. This website is for educational purposes only and you are responsible for everything you do with the given information. You are responsible for the health and welfare of your own body and computer.

I hope this iMac repair training course series of articles helps everyone that is facing a decision of possibly having to go to the precious and non-ferrous metal reclamation and computer electronics recycle center with their crippled or broken down Apple iMac now and in the future. After all, I believe that these Apple G5 iMacs are not an EWaste product, and are most precious and beautiful machines for their owners to use. I think there is a lot of life left in these very powerful iMac G5 computer machines for today and tomorrow. At least I have a documented road map and general circuit diagram schematic of the main power supply components, along with engineering failure analysis that I will be using myself for technical reference for now and in the future. By-the-way, I now have a large quantity of high quality, low ESR, electrolytic capacitors available for sale for the DIY Apple iMac G5 motherboard repairs. See motherboard repair posting for quantities required. Or, you can order directly from my online store at Out West Sales today.

Power Supply iMac 20 Inch Model Apple Part Number — Apple p/n: 614-0326

Capacitor List and Diameter Sizes For Power Supply Apple iMac 20 Inch

Click this iMac 20” PSU Super Close-up View or Picture Above for Close-up View
  • 330uf    35v    10mm
  • 1200uf   16v    10mm
  • 3300uf   10v    10mm
  • 2200uf   10v    10mm
  • 1000uf   25v    10mm
  • 1000uf   10v    8mm
  • 120uf    50v    8mm

This particular power supply is (Apple p/n: 614-0326)

Note: According to Alex, capacitors would not exceed 32mm length. But also note that the cable wiring comes over the top of some of those capacitors on the right front section of the PSU. If the capacitors are too high, the wiring will not clear the PSU cover.

“Jim – do you have a pic of a 20″ iMac G5 power supply guts? Mine had the bulging/leaking capacitors. I removed them but need 2 reinstall and lost my notes as to which went where. On the top right hand side area is where they go.

I need to know where each size goes back. They are as follows: 1200mF 16V, 3300mF 10V, 2200mF 10V and 1000mF 10V any help is greatly appreciated.”

Sorry, I haven’t taken the 20 inch power supply apart, so I don’t have any pictures. I’d appreciate it if someone else can send pictures to me of the 20 inch model and I’ll post them here. Click my email address “James” on the right side to send images. Special thanks to Alex B. for his Power Supply iMac 20” picture above.

Additionally, if anyone finds a source available for engineering prints, technical drawings, or electronic schematics for Apple iMacs, please send me an email notice or send attachments to James. James is my clickable email address located on the right side of the website, just above “Chat with Jim Warholic” when I’m available online. I and others would really appreciate the circuit board schematics if you have them. Thank you, Jim Warholic

There is another option worth exploring for the Apple iMac G5 Power Supply. The option is to possibly convert a standard PC ATX power supply and use it for the Apple iMac. Wiring changes on the P1 pin-outs have to be made first. See the following note and image.

Accelerate Your Macintosh! News Page

iMac G5 Power Supply Connector Pin-Out (Voltages)
“I haven’t been able to find this anywhere using Google, so I took apart my iMac G5 (17-inch rev A) power supply and made a pin-out diagram.
-Chris N.”

Do not attempt the following if you do not know what you are doing. Severe damage could result. See note above concerning the information provided here. Compare the Apple iMac Pinouts diagram with that of the ATX Power Supply Pinouts Diagram. Pin modifications need to take place before plugging it in. Note also, there is a 24 Volts output on the Apple iMac Pinout diagram that is missing on the ATX Power Supply Pinout diagram. However, based on a thread in an online Apple Forum at InsanelyMac, titled iMac G5 Power Supply Question, a person as recently as January 2008 modified an ATX power supply and didn’t use the 24V, but I think he used an external monitor, and the iMac worked with this setup. Some folks indicate that the +24V is used for the internal backlit display. See quotes: “+24V is used to power the LCD inverter” and “24VDC line looks to be for the display (backlighting)”. Read full quotes in context at InsanelyMac Forum.

With that iMac G5 mod in mind, maybe someone can come up with an external power supply box, and just plug it in to the iMac P1 plug on the motherboard. Another person also emailed me in October of 2008 and mentioned he had this ATX power supply working for an Apple iMac g5 too.

This was recently posted as a comment by another person for the pin outs and voltage information: Note, I have confirmed this pin out information. Update: The various pinouts have been confirmed by at least one other customer also. Click the how-to link for more details about how to measure the iMac G5 power supply voltages and turn on the PSU when the PSU is removed from the iMac computer.

My 20″ iMac Power Supply connector – P-1

1. +3.3 – BlackA3B 12. +3.3 – BlackA3B
2. +3.3 – BlackA3B 13. +12v – BrownA3B
3. GND – BlackB4B 14. GND – BlackC4B
4. +5v Gray/PurpleA4B 15. On/Off – Gray
5. GND – BlackB4B 16. GND – BlackC4B
6. +5v Gray/PurpleA4B 17. GND – BlackC4B
7. GND – BlackB4B 18. GND – BlackC4B
8. PG – Blue 19. +12v – BrownA3B
9. +5.1Vsb – Purple 20. +5v Gray/PurpleA4B
10. +12v – BrownA3B 21. +5v Gray/PurpleA4B
11. GND 22. +20v – Brown

FYI: More information for measuring the voltages can be found at my how to measure iMac G5 power supplies article. Be sure to read the article comments section for additional details.

Pin 22 supplies Panel voltage. Using a modified ATX Power supply (Need 12+ on pins 12 and 18), and the good 20 volts on the dead Apple Power Supply and a ground, I was able to boot my 20″ iMac using the combination of both power supplies. Someone else posted the pin out elsewhere on the web. I replaced just the domed capacitors on my power supply and still no luck. Can some of the capacitors be bad and not be domed? Can you check capacitors on the board without removal? Some go to infinite and stay, other go to infinite and fall back to zero when using an ohm meter?

A few points to consider when checking capacitors in the circuit and on the circuit board. It doesn’t always give the correct reading with a ohm meter whether using digital or analog  meters because of other components affecting the readings of what you might be trying to check in the circuit. Yes, capacitors can be bad without physically looking bad. The electrolytic juice can dry up on the inside. And one more point that I would like to make, it sure would be nice to have a circuit board schematic for the power supplies in my hands. Feel free to send me one if you have it. Thanks.

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3/18/2009 Update: Installed new power supply in this iMac 17 inch G5 computer. Success! Installed keyboard and mouse too. Now I need new software for the white house.

A important note here is that I recommend only using “new” low ESR, long life, computer motherboard grade and switching power supply grade capacitors for all repairs. Do not use unknown surplus caps, or even new or surplus caps that have been sitting on the shelf for ages. My power supply was too far gone. It had something else blown in it.

I have the extra long life capacitors (rated at 10,000 hrs. on the large uf rated capacitors) and all are low ESR ratings for the power supplies, in stock now. Please take a look and compare these Apple iMac power supplies to your power supply before purchasing.

Click Here to Buy Capacitors, or click here to match up your iMac PSU variation to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards.

If your iMac power supply doesn’t look exactly as above, or would like to have a free consultation, and provide a visual evaluation for me to take a look at please send in your Apple iMac G5 pictures, to compare.

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Two Monitors on iMac With Free Screen Spanning Software

It is possible to install an extra monitor on an iMac G5 computer and have what is known as “screen spanning” which is an extended desktop mode of operation. Widgets New LCD Widescreen Flat-Panel Monitor Recommendations Screen spanning is where your screen desktop area is extended to include the extra monitor (not a duplicate [...]

Click to read more about: Two Monitors on iMac With Free Screen Spanning Software

It is possible to install an extra monitor on an iMac G5 computer and have what is known as “screen spanning” which is an extended desktop mode of operation.

New LCD Widescreen Flat-Panel Monitor Recommendations

Screen spanning is where your screen desktop area is extended to include the extra monitor (not a duplicate of your existing display). There is a small Apple mini VGA to regular VGA plug short adapter cable that is required to go from the small VGA port on the back side of the iMac computer and plug the other end into the monitor cable.

The original Apple OS X software for the iMac G5s did not provide screen spanning capabilities. The hardware can handle it, but Apple chose not to enable it in the software. Not sure the reason behind Apple’s decision on that. Apple only supported dual monitors with both monitors displaying the same information on the screens at the same time. However, there is a free software modification that can make use of the hardware capabilities of the internal video card on the motherboard in the iMac G5 computers. The video card on the iMac G5 20 is a built-in nVIDIA GeForce FX 5200 directly mounted on the motherboard. The iMac motherboard essentially provides the means to have two monitors using the Apple Mini-VGA to VGA Display Adapter for a Mac. The mini-VGA adapter will cost you somewhere around $20.00, including shipping charges, to purchase from Amazon. You might be able to buy one for a little bit less.

You can download the latest version of the Screen Spanning Doctor (v0.3.3) software. Screen Spanning Doctor (0.3.3) supports Tiger. Click on the link to be sure your Apple computer is compatible and able to make use of this software mod. The software patch was for the iBook, eMac, and iMac computers. You can view which models are supported. Please note, the site has the following disclaimer that I would also have to echo too:

“Please note that I cannot be responsible for any damage that you might do to your computer. This site is for educational purposes only and you are responsible for everything you do with the given information. …”

The cool part about this addon monitor screen spanning mode of operation, is it can have its own separate monitor configurations for screen resolutions, and even the background picture for the desktop can be different too. The screen saver program can display different designs on each monitor. It doesn’t mean you can have different screen savers running at the same time, it just means that a Screen Saver like Cosmos, which has different images from the universe, each monitor will display a different image at the same time. I personally have installed the screen spanning software on my iMac G5 and it works terrific for me.

If you are thinking to use an extra monitor because your Apple iMac G5 20 or iMac G5 17 inch is having main display problems, your problem might actually be a bad motherboard. The capacitors for the video display unit located on the iMac G5 Mainboard go bad (burst open, leak electrolytic fluid, and dry up) along with additional filtering capacitors that blow up on other areas of the motherboard. Refer to the article I wrote about How to Repair Apple iMac G5 Motherboards and replace those bad capacitors. Or, the problem may be with your Apple Power Supply Unit.

When an extra monitor is plugged in to the port on the back of the iMac G5, the Apple software senses a new monitor is installed and provides the available screen resolutions for each, on each monitor. So, when you go to System Preferences, and click on Displays, the configuration settings appear on each of the monitors’ screens with each specific configuration particular to each monitor. Arrangement of the monitors can be on the left, right, top, or bottom by simply dragging the monitor to the position you would like. If you decide to have your monitors stacked on a shelf, one above the other, you can place the monitors under one another on the setup screen. If you wish to have them on your desktop, side-by-side, then place the setup screen on the left or right. When your monitors are set up the way you want, the mouse will track accordingly. For example, if you have your monitors side-by-side, then when you move your mouse to the right, you will then go over to the other screen. This is handy if you regularly have lots of windows open and wish to expand your Mac desktop area. Or, you can have one application on display on one screen and have another running on the other. Just drag the open software application screen to the other monitor. Colors can also be calibrated between each of the screen monitors too.

With the price on large screen LCD monitors having dropped significantly over the years, now is the time to add more real estate graphic exposure to your desktop area today.

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