atx power supply

How to fix a computer that won’t turn on

Dave Farquhar Hardware , ,
How to fix a computer that won’t turn on

When a computer won’t turn on, it’s usually a simple repair you can do yourself. Frequently it doesn’t cost anything and doesn’t require any parts. If you do need parts, you can expect it to cost $70 or less and get it done in less than an hour. Here’s how to fix a computer that won’t turn on.

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Using PC ATX power supplies on a train layout

Dave Farquhar model railroading, Toy trains , ,
Using PC ATX power supplies on a train layout

PC power supplies are exceptionally cheap and plentiful these days. If you’ve noticed and wondered whether you can use PC ATX power supplies on a train layout, wonder no more. You can.

Thanks to the miracle of mass production, even the cheapest, nastiest PC power supply gives far more power output per dollar than any train transformer. So if the lights and accessories on your electric train layout can run on 12 volts DC, which is a fairly good bet, you can get a lot of wattage for very little money by repurposing an inexpensive ATX power supply, whether new or secondhand. And on a wattage-per-dollar basis, they’re about twice as cost-effective as outdoor lighting transformers, which are another popular option for hobbyists. If you need AC power and more than 12 volts, get a lighting transformer. Otherwise, you can go ATX.

All it takes to use these cost-effective ATX power supplies is a bit of rewiring.

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Curious conspiracies… or maybe just progress all at once

Dave Farquhar security , , , , , , , , , , , , , , ,

In the wake of Truecrypt’s sudden implosion, someone sent me a link to this curious blog post. I can see why many people might find the timing interesting, but there are a number of details this particular blog post doesn’t get correct, and it actually spends most of its time talking about stuff that has little or nothing to do with Truecrypt.

What’s unclear to me is whether he’s trying to say the industry is deliberately sabotaging Truecrypt, or if he’s simply trying to make a list of things that are making life difficult for Truecrypt. His post bothers me a lot less if it’s just a laundry list of challenges, but either way, the inaccuracies remain. Read more

Used dual-cores are coming! Used dual-cores are coming!

Dave Farquhar Hardware , , , , , , ,
Used dual-cores are coming! Used dual-cores are coming!

All this talk about new computers got me looking to see what’s out there in the channel. And it looks like the glut of Pentium 4s is finally clearing, making way for the 2-core revolution. Prices are low–I’m seeing dual-core systems, both Intel and AMD, with Windows licenses, for anywhere from $180 to $280 depending on configuration and some other factors that aren’t exactly clear to me.

Sound good? Here’s what to look for in an off-lease/refurbished computer.
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The rise and fall of Shack, and how to fix it

Dave Farquhar Retro Computing , , , , , , , , , , , , , , , , , , , , , , , , , ,

Wired has a nostalgic piece on the not-quite-late, not-quite-great Radio Shack. I think it’s a good article, but it glosses over part of the reason for the store’s decline.

It blames computers.But blaming computers ignores Tandy’s long and successful run in that industry. Most Apple fanatics and other revisionist historians conveniently overlook this, but when Apple launched the Apple II in 1977, Tandy and Commodore were right there with competing offerings. I don’t know about Apple, but Tandy and Commodore were selling their machines faster than they could make them.

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Replacing wall warts with PC power supplies

Dave Farquhar Hardware , , , , , , ,

I wrote a long, long time ago about my adventures trying to find a wall wart for my old 8-port Netgear dual-speed hub. The other day I stumbled across a novel idea for a replacement.
I won’t rehash how you determine whether a unit is a suitable replacement–read the above link if you’re curious–but suffice it to say a $5 universal adapter from Kmart is fine for my answering machine or my cordless phone and can probably provide the 5 volts my Netgear needs, but my Netgear also needs 3 amps and the universal adapter I keep around can only deliver 20% of that. The beefiest 5v unit I could find at Radio Shack could only deliver 1.5 amps.

A PC power supply delivers 5V and 12V on its hard drive connectors. And PC power supplies deliver plenty of amperage: one of mine will deliver 25 amps on its 5V line, and 10 amps on its 12V line.

In a pinch, I could just obtain a suitable plug barrel that fits my Netgear from Radio Shack, clip the power connector off a dead CPU fan, and solder the plug to the red wire (5 volts) and a black wire (ground), put it in a PC, and use that to run my Netgear hub. The increased power draw would be equivalent to putting three typical PCI cards in the system. Just be sure to wire things right–reverse polarity can kill some devices.

Rather than using one of the PCs I actually use, it would be better to obtain a cheap microATX case, short the green and one of the black wires on the 20-pin motherboard connector with a paper clip, insulate the paper clip with electrical tape, and then wire things up to the drive connectors. Or, for that matter, you could use some of the other leads available on the 20-pin connector if you have a device that needs 3.3 volts (pinout here.) You could also just use a bare ATX power supply with a paper clip connecting the green wire and one of the black wires on the 20-pin motherboard connector, if you’re into the ghetto look.

An AT power supply would also work and it offers the advantage of being really cheap and common (here’s a nice writeup about an AT power supply’s capabilities), but most AT boxes require you to hook up enough 5-volt devices to chew up about 20% of its rating on that power rail before they’ll power up. I have a 200-watt AT power supply that delivers 20 amps on its 5-volt rail, so my 3-watt Netgear hub probably wouldn’t be quite enough on its own. So it might be necessary to either connect an obsolete motherboard to the power supply or connect a 1-ohm resistor between a +5 lead and ground, if you don’t have a plethora of power-hungry 5-volt devices to plug in.

But PC power supplies provide a cheap and commonly available way to replace odd wall warts, or at the very least, to reduce the clutter around the computer room.

Upgrade diary: Gateway G6-400

Dave Farquhar Hardware , , , , , , , ,

I recently had the displeasure of working on a Gateway G6-400. I’ll relate some of the experiences here, in case you ever have the same misfortune.
The G6-400 looks good on paper. This particular configuration had a P2-400 in it on an Intel mobo (BX chipset), a 16-meg 3dfx video card (hot for the time), and a DVD drive. The owner complained it was slow and unstable. The usual cure for that is to remove the extra crap Gateway installs on all their PCs.

Unfortunately, this one wouldn’t boot to let me do that. Not even in safe mode. Nice, eh?

Memory problem? I tried several known-good DIMMs. Same results.

Power supply? I tried a known-good, brand-name power supply. Same results.

At some point, the hard drive made an ominous noise. I replaced the hard drive and attempted a clean install of Win98SE. It bombed out at random points during installation. Just in case it was the DVD drive, I tried several different CD-ROM drives. (Hey, I was desperate.) Same result.

Out of curiosity, I put the suspect hard drive in another computer and tried to boot it in safe mode (I didn’t want Windows to mess up the configuration). It worked fine. Rats.

So by now I’d replaced everything in the box–everything important, at least–except the mobo and the processor. I spied an FIC P2 mobo with a BX chipset at Software and Stuff for 30 bucks. I bought it. I was playing the odds. Mobos go bad more often than CPUs do, especially when you’re not overclocking. And if I was wrong, I have other Slot 1 processors. The only other Slot 1 mobo I have is one of the really old LX-based boards that only has a 66 MHz bus.

Why pay $30 for an obsolete mobo when you can get a modern board for $50 or $60 and put a nice Duron or Athlon CPU on it? I doubted the power supply would handle it well. Spend $30 more on a mobo, and $30 more on a new CPU, then you have to replace the power supply as well. Suddenly $30 more has become $100.

The FIC is a much nicer board, even though the specs are very similar. It has one more DIMM slot than the Intel board had. It has no onboard sound, but it has one more available PCI slot. Expandability comes out a draw (you’ll use the extra PCI slot to hold a sound card), but you get your choice. You can put in something equivalent to the midrange Yamaha sound built into the Intel board. Or you can put in a high-end card. The board itself has a lot more configuration options, and even with the default options it boots a lot faster.

This G6-400 has a microATX power supply in it. At least it looks like a microATX power supply, and a lot of people who sell eMachines-compatible microATX boxes claim they’ll also fit a G6. Why Gateway put a small-form factor, low-power power supply in what was at the time of manufacture the second-fastest PC on the market, I have no idea. Unless the idea was to make lots of money selling replacement power supplies. The plus side is, at least it really is ATX, unlike Dell, who uses something that looks like ATX but isn’t. (You’ll blow up the mobo if you plug an ATX power supply into a Dell mobo or a Dell power supply into a standard ATX mobo.)

Fortunately, this case has screw holes in the standard ATX places as well. Unfortunately, the opening in the back isn’t big enough to accomodate any standard ATX power supply I’ve ever seen (the opening blocks the power plug). Someone willing to resort to violence with a hacksaw, Dremel (or similar tool), or tin snips could hack an opening big enough to accomodate a replacement box. More on that in a bit.

I pulled the Intel mobo and dropped in the FIC replacement. Unfortunately, the case used one big block for all the case switches. Since nobody’s ever standardized the header block for the and reset switches and lights, that’s a problem unless you’re replacing boards with a board from the same manufacturer (assuming manufacturers never change their header block pinouts, which isn’t exactly a safe assumption). But that wasn’t the only problem I ran into with this motherboard swap.

Remember that power supply I told you about? Turns out the power lead on it is just long enough to reach the power connector on the Intel mobo the machine came with, in front of the memory slots. FIC put its power connector on the other side of the CPU, and the cable is about half an inch too short to reach. Good luck finding an ATX power extender cable. Directron.com has one for $5, but the minimum order is $10 and that’s before shipping. A search on Pricewatch.com only listed a couple of places having them. Pricing was under $10, but then there’s shipping. I found one computer store in south St. Louis County that had ONE in stock. “They’re not cheap,” the salesperson warned me. I asked how much. $16.95. “You’re not kidding,” I said. That’s half the price of a new 300W power supply. Of course, by the time you pay $5 online and $10 to ship it, $16.95 looks a lot more reasonable, doesn’t it? And if your case won’t accomodate a standard ATX power supply, either buying one of these or buying a similarly overpriced microATX power supply may be your only choice.

To get things up and going, I just jerry-rigged it. I ran the power cables and found a place to rest the power supply where it wouldn’t short out anything. Then I shorted the power leads on the mobo with a screwdriver, and booted Windows 98 in safe mode. It booted up just fine, after insisting on running Scandisk. I booted into regular mode, which insisted on running Scandisk again. It worked beautifully. I did some very minor optimizations (Network server in filesystem settings, turning off Active Desktop, etc.) and rebooted a few times. No problems. No weirdness. Everything was smooth and fluid.

The chances of me ever buying a Gateway (new at least) already approached zero before this adventure. The few Gateways I dealt with in my years doing desktop support always had goofy problems that I usually had to reinstall the OS to resolve. Meanwhile, the Micron or Dell in the next cubicle over kept on chugging away, never needing anything more than basic maintenance.

This motherboard swap is easily the most painful swap I’ve ever done. It worked in the end, but the power supply was an annoyance and an unplanned expense. The header block was an annoyance.

So if you’re thinking about a motherboard swap in a Gateway, particularly a G6 series, don’t plan on it being a walk in the park.

A safe way to test power supplies

Dave Farquhar Hardware , , , , ,
A safe way to test power supplies

Sometimes when a computer refuses to power up, it’s due to the power supply going bad. Here’s a safe way to test power supplies.

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Spontaneous system reboots

Dave Farquhar Troubleshooting , , , , ,

Steve DeLassus asked me the other day what I would do to fix a PC that was rebooting itself periodically. It’s not him who’s having the problem, he says, it’s someone he knows. He must be trying to show up someone at work or on the Web or something.
So I gave him a few things I’d check, in order of likelihood.

Static electricity. A big static shock can send a system down faster than anything else I’ve seen. Keep a humidifier in the computer room to reduce static electricity. If you’re really paranoid, put a metal strip on your desk and connect it to ground (on your electrical outlet, not on your PC) and touch it before touching your PC. Some people metalize and ground part of their mouse pad. That’s a bit extreme but it works.

Power supply. This is the big one. A failing power supply can take out other components. And even if you have an expensive, big-brand box like a PCP&C or Enermax, they can fail. So I always keep a spare ATX power supply around for testing. It doesn’t have to be an expensive one–you just want something that can run the machine for a day or two to see if the problem goes away.
Overheating. Check all your fans to make sure they’re working. An overheated system can produce all sorts of weird behavior, including reboots. The computer we produced our school newspaper on back in 1996 tended to overheat and reboot about 8 hours into our marathon QuarkXPress sessions.

Memory. It’s extremely rare, but even Crucial produces the occasional defective module. And while bad memory is more likely to produce blue screens than reboots, it’s a possibility worth checking into. Download Memtest86 to exercise your memory.

CPU. If you’re overclocking and experiencing spontaneous reboots, cut it out and see what happens. Unfortunately, by the time these reboots become common, it may be too late. That turned out to be the case with that QuarkXPress-running PC I mentioned earlier. Had we replaced the fans with more powerful units right away, we might have been fine, but we ended up having to replace the CPU. (We weren’t overclocking, but this was an early Cyrix 6×86 CPU, a chip that was notorious for running hot.) Less likely today, but still possible.

Hard drive. I’m really reaching here. If you’re using a lot of virtual memory and you have bad sectors on your hard drive and the swapfile is using one or more of those bad sectors, a lot of unpredictable things can happen. A spontaneous reboot is probably the least of those. But theoretically it could happen.

Operating system. This is truly the last resort. People frequently try to run an OS that’s either too new or too old to be ideal on a PC of a particular vintage. If the system is failing but all the hardware seems to be OK, try loading the OS that was contemporary when the system was new. That means if it’s a Pentium-133, try Win95 on it. If it’s a P4, try Windows 2000 or Windows XP on it. When you try to run a five-year-old OS on a new system, or vice-versa, you can run into problems with poorly tested device drivers or a system strapped for resources.

Another good OS-related troubleshooting trick for failing hardware is to try to load Linux. Linux will often cause suspect hardware to fail, even if the hardware can run Windows successfully, because Linux pushes the hardware more than Microsoft systems do. So if the system fails to load Linux, start swapping components and try again. Once the system is capable of loading Linux successfully, it’s likely to work right in Windows too.

Troubleshooting advice: When you suspect a bad component, particularly a power supply, always swap in a known-good component, rather than trying out the suspect component in another system to see if the problem follows it. The risks of damaging the system are too great, particularly when you try a bad power supply in another system.

And, as always, you minimize the risks of these problems by buying high-quality components, but you never completely eliminate the risk. Even the best occasionally make a defective part.

01/03/2001

Dave Farquhar General , , ,

Mailbag:

Dual Celerons; Chap. 9

Dead ATX power supplies. Yesterday was my first day back at work in a while (I was burning up vacation time most of last week). I “fixed” an ATX power supply first thing that morning by unplugging it and plugging it back in after waiting 10 seconds. I see that problem somewhat frequently on Micron desktop PCs for some reason. If it gets to be a regular occurrance on a particular PC, we get Micron to RMA the power supply.

Mac-PC font conversion madness. We also ran into some problems migrating some documents from Macs to PCs, so the resident Unix guru, who’s also the other resident Mac guru, and I spent all afternoon struggling with it. Finally, we just started converting a couple of the crucial Type 1 (PostScript) fonts manually to get around the problem. He had his Linux laptop with Netatalk configured, so I dumped the fonts to his Linux box, which he then converted and I grabbed on a PC via FTP.

There is no good free way to move fonts between the Mac and Windows, alas. From the Mac to Unix is no big deal. But all the freebie converters have major drawbacks. I went and got the $45 shareware CrossFont from www.asy.com and tried it out. It gave satisfactory results on two of the fonts, but totally mangled the line spacing on the third. We suspect that font has problems, so it may not be CrossFont’s fault, but it would be nice to know for sure.

Speaking of Type 1, Adobe Type Manager Light is now a free download for both Windows and the Mac. Get your copy at www.adobe.com. There aren’t a huge number of free PostScript fonts out there, but there are some.

The Epson Stylus 1520. Today was a Mac problem day mostly. I ended the day by troubleshooting an Epson Stylus Color 1520 that didn’t want to print pure colors. Pushing the clean button didn’t help. I finally just switched over to the printer’s local port (we usually print via the Epson Stylus RIP to get PostScript Level 3 support), opened an application, loaded a file, chose to print, then hit the Utility button from the print dialog box. I do wish there were an easier way to get to the utility function. I cleaned the nozzles and aligned the print heads, and voila, we once again had nice prints.

Too bad Epson hides that utility so deeply, because I spend a lot of time cleaning those stupid printers and that’s really something an end user could do, if they could remember how. (I have a hard time remembering how, which is part of the reason why I’m putting it here. Running a Web site has its advantages…)

The other problem I have with this printer is that because it cost $500, people seem to think it’s a high-volume printer, capable of printing thousands of pages a month. It’s not. It really is a consumer-grade printer. While the print quality is very good as long as you have the right paper, that’s this printer’s appeal, and that’s why it costs so much. Printing thousands of sheets a month is a great way to burn through printheads, and that’s not something that’s user-replaceable. It’s not even something I can do–it has to go into the shop. And no, when you pay $500 for a printer, you don’t get onsite service.

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Dual Celerons; Chap. 9