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Dell D400 Laptop

Case Study 1: Repairing a Dell Latitude D400 Laptop


In the United States, we waste far too many old computers by giving in to the pressure to hand them over to "recyclers", companies that destroy computers and ship them to land-fills in third-world countries. Most of these computers are still useful, and many people who can't afford to pay several hundred dollars for a brand-new computer would like to have one. They may just have difficulty finding one for a good price, because we "recycle" so many of them.

In the hope that readers of this website will begin to recognize the waste involved in destroying perfectly good, old computers, I have decided to write articles from time-to-time about the old laptops I have acquired and restored to working condition. Sometimes, I even find them in great working condition, just waiting to be put to good use.

My Dell Latitude D400 Laptop:

This week, I will be writing about my Dell Latitude D400. I found my D400 several months ago at a local thrift store for $14. The D400 was designed to be a light-weight (for the time) travel laptop for business people. Sixteen years ago, it's maximum RAM capacity of 2GB was considered to be enormous. And, it came with the buyer's choice of three "spacious" hard drive sizes: 20, 30, and 60GB. It also has a PCMCIA card expansion slot. The D400 that I found had the following configuration:

When I took the D400 home and turned it on, this is what I saw:

Bad BIOS Battery

This message means that the BIOS battery (sometimes called the CMOS battery) is no longer charged. The BIOS battery keeps the CMOS memory powered. CMOS memory is used to hold the BIOS configuration that the user or manufacturer has input. It's similar to RAM in that it requires continuous power to hold information. Some of the information held in CMOS memory are the boot drive order, the time and date on the computer's clock, the amount of RAM, and the size of the hard drive.

Unrelated to the above message, I also found that the operating system had become corrupted on the hard drive, so the laptop would no longer boot. Here is a complete list of things that I found wrong with this laptop:

The laptop battery holds a charge, but I haven't tested it to see how long it powers the laptop.


I have a few Dell D and E-series laptops. They all use the same power supply, so that wasn't a problem.

I ordered from Ebay a new keyboard for $11 and a new BIOS battery for $8.89. The shipping was free for both items. That is all the money I spent on this laptop.

Before attempting any repairs, I downloaded a Dell Latitude D400 Service Manual from the Dell website. After following the service manual's directions for taking the back off the laptop, the BIOS battery is visible. It's the green, bar-shaped object at the top center of the picture through which the outlines of six button-cell batteries are visible.

D400, back removed

The BIOS battery is held in place with double-sided tape, so I had to pry it off the motherboard with a plastic spudger after disconnecting its two-wire connector from the motherboard. I put new double-sided tape on the new battery, stuck it to the motherboard and connected its connector. I noticed that the black and red wires on the new battery seemed to be in the opposite orientation as those of the old battery. That made me wonder if the manufacturer of the new battery may have attached the wires incorrectly. The male BIOS battery connector is shaped so that it can only be inserted it into the female motherboard connector in one orientation, so there is no possibility that I could have attached it wrong.

The keyboard is removed by prying off the plastic strip just above it with a plastic spudger. The plastic strip is held in place by clips that release with a bit of prying pressure. All the Dell D-series laptops of which I'm aware have this plastic strip. Once the plastic strip is off, the two screws holding down the keyboard are visible. I unscrewed the two screws at the top of the keyboard and lifted it out, being careful not to damage the keyboard ribbon that is connected to a socket on the motherboard. I disconnected the ribbon and connected the new keyboard, screwed in the screws, and pressed the plastic strip back into place. This procedure is detailed with illustrations in the service manual.

After the keyboard and BIOS battery replacement were completed, I put the laptop back together.

The D/Bay/USB port is a far-too-delicate port that has 4 floating-wire contacts (for lack of a better term). Looking at it with a magnifying glass, I noticed that the second contact wire had been bent into the back of the USB port and was no longer making contact. So with a pair of tweezers and a pair of needle-nose pliers, I bent the wire back into position. That was enough to get the port working again. Luckily, the bent wire had not caused the USB controller chip in the laptop to burn out.

I installed the Zorin 9 Lite distribution of Linux on the hard drive, and it seemed to work just fine. Several months later, the hard drive still works without any problems.

A note came with the new BIOS battery saying this particular battery is rechargeable and to plug in the laptop for 24 to 48 hours to charge it initially. If I had known this before buying a new BIOS battery, I would have tried applying power to the laptop for 24 hours to see if the old BIOS battery would recharge.

After plugging in the laptop for 48 hours, I didn't get a bad BIOS battery error message. However, a few days later the bad BIOS message reappeared at boot. I don't know whether this is due to the wrong polarity on the BIOS battery wires or to the manufacturer's battery being bad. This was disappointing after the work I put into replacing it. However, this is really just an inconvenience. It just means that if I haven't had the laptop plugged in for a few days, I have to press the "F1" key at boot-up. No big deal, since I don't care about the accuracy of the date and time. Laptops made in the last twenty years automatically detect the hard drive configuration at boot, which prevents hard drive configuration issues due to a dead BIOS battery. Aside from the BIOS battery problem, the D400 works fine now.

My total cost to purchase and repair this 16-year-old laptop was $33.89. I can't say this is a great deal. But it's okay, and I may have saved another laptop from a land-fill.

The point of this article is to show readers that old computers can often be salvaged with a few simple tools, a service manual downloaded from the manufacturer's website, and a few hours of work. I plan to write more of this type of article as I find more interesting old laptops to write about.

Related Articles:

The Basics of Repairing and Upgrading an Old Laptop Computer

Case Study 2: A Thrift Store Gateway KAV60 Laptop

Why used Computers can be such Good Deals

What Happens to Recycled Computers?

How to Fix a Slow Computer

How to get a Cheap Laptop


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