Dell Optiplex SX260 Computer Won't Boot Up

No POST beeps or light codes? If it is using a separate graphics card, remove and/or substitute. Try different RAM.

Bad electrolytics.

I have two of these computers. Onboard video, uses DDR2 RAM: PC2-5300 ? CL=5 ? Unbuffered ? NON-ECC ? DDR2-667 ? 1.8V ? 128Meg x 64 It should boot on a single module.

This model is well known for bad electrolytics. So much so that a kit is offered for it:

Also, they small power supplies fail more often than power supplies in larger systems. Some of those are just bad electrolytics, as well.

Bulging capacitors on the motherboard. Probably nothing wrong with the DA-1 external power supply, but it would a good idea to check if you're getting 12VDC on the output. Also, put a scope on the 12V PS output and look for noise. So far, I haven't found any bad power supplies, but I've fixed about five of the SX260/270 boxes with bad caps on the MB. It's not horribly difficult to replace the caps, but it's tedious. Also, getting the motherboard out of the case is a bit of a challenge around the rear panel green locking mechanism.

If you don't mind the shotgun approach, try a rebuild kit. etc...

Hint: The fastest CPU that will work in the SX260 is 2.8GHz with hyperthreading.

I have three of them. However, only one works and I only have one power supply. The other two are waiting for time to fix, or recycling (toss a coin).

I replace enough caps to justify buying 25, 50, or 100 at a time.

Huh? I haven't seen any of the external 12V power supplies that have failed. I think I've gone through about 8 of them so far, mostly used on a previous generation of weather stations. I've been tempted to see what range of voltage the SX260 will operate. I want to put it on a storage battery and charger system, which means anything between

On Thursday, February 14, 2013 7:29:13 AM UTC-8, snipped-for-privacy@verizon.net wrote :

oot up. When I press the power button, there is no display on monitor, no H DD spin up noise. The only "life" I see/hear is the power light comes on an d the fans run. I tried a bootable CD, but the CD drive doesn't "run". Note : I protected against static damage using a ground strap to my body. I chec ked all the on board fuses (all good), solder joints, and power supply outp ut voltages with a load. The CMOS (RTC) battery is good. I even removed and reinstalled the CPU. Did anyone have the same problem with this model comp uter? Thank You in advance, John

I think that instead of thinking about this as a Dell computer problem, yo u might look at the problem as what would cause *any* desktop to not boot. It's been a long while since I've knocked together desktop computers, but w hen one didn't boot it was because of simple things like conflicting cards, or even a keyboard problem. Checkout this

for some really good troubleshooting tips.

Ron

I can only find one right now, and didn't think it was worth repairing. The hard drive & CDROm drive are now missing, and it had no bulging or leaking caps. Since I repair the computers to give away, it doesn't make much sense to spend money & time on it. It was in the TBPO pile.

I buy most 100 at a time, too.

Why not use a switching converter that boosts then bucks the voltage so you can run it anywhere you want. I'm currently working on a 12 to

Hi Jeff,

The kit, which includes a location of the bad caps (great idea), is for a Dell GX-620, which is not even close to my Dell Optiplex SX260 mother board's layout. Note: This desktop PC is small and was made in 2003.

Did any of those bad caps have a bulge? Note: I have equipment to measure and check ESR of caps.

Thanks in advance, John

I could use a 12v to 12v DC to DC converter to deal with the input range. However, these weather stations are mostly on mountain top radio sites, where the switching noise would not be welcome. I've had problems with this in the past and would like to avoid it. We have a perfectly good 12V battery based system running the stuff that will run on 12VDC, which is most everything these days. I just wanted to add the SX260 to the 12V battery bus. The only problem is not knowing the range of voltages it will tolerate. I guess I'll have to sacrifice an SX260 or SX280 and see what blows up. (I've failed to find schematics).

Well, there are battery eliminators for such radios, but they mostly run on 117VAC.

Yeah, that's the killer. I have the stock 12V to 117VAC converter that bolts onto the back of my Wavetek 3000B service monitor. Running on 12VDC, it generates enough noise to make the receiver in the service monitor useless for anything except very strong signals.

Umm... that was Mike, not Jeff.

Yes. However, I check every cap with an old Bob Parker ESR meter. Lately, I've been getting lazy, buying kits, and replacing all the caps, even if they look and test good. I'm tired of tearing apart machines more than once to replace the one cap that I missed. However, the SX260 has 30 caps, 9 of which are inconveniently buried under the voltage regulator heat sink. I had to replace all 9, and some of the others that tested bad. I wasn't going to replace 30 caps on such an old unit. Not fun, but I've done it often enough that I can do it fairly quickly with my antique desoldering station. If I'm in a rush, I'll use the hot air desoldering station, which melts the solder on both leads of the capacitor at the same time (but also tends to melt everything around the capacitor).

I have one dead 260 I'm not going to bother with. I'd givve it to you, but shipping from Florida is probably more than it's worth.

The radios I'm interested in will play on 117 AC or DC as built.

I learned a lot at Microdyne about filtering. People won't pay $20,000 to $80,000 for a receiver that has internal noise problems.

I'm not Jeff. :)

Sorry, I've been working on the GX620s and am using one for Usenet & Email. They have kits for several other Dell models.

Thanks, but I don't think a dead computah is going to help. I need to see if it will actually run on a range of DC voltages. I'll let you know how it goes when and if I find time to play.

Yep. Self-interference sucks but is all too common. My IFR-1500 service monitor has a built in 117VAC and 12VDC combination power supply (single unit). I gave up on fixing the AC section and am running it on DC. The switching noise isn't bad, but it's there. I added some ferrite "beads" which made it usable.

You've probably seen these: "Powering Your Antique Battery Radio" <

Yes. Philip Nelson was a regular on news:rec.antiques.radio+phono for years.

That's another AC to DC supply. I want a rechargeable battery pack with built in DC-DC converters for the 90 V plate & 9 V filament supplies.

A lot of people do crap like this:

Which is a 42 cent corregated paper mailer from

BTW, Jeff Angus is back on a few newsgroups, but he can't access this group most of the time. He is posting as Fox's Mercantile. :)

Hi,

Here is an update:

Using a "lo-pwr ohms" (low voltage) B&K meter, I measured about 5.5 ohms across the bank of 2200/6.3 caps numbers C146, C147, C148, etc. Note: This reading is not caused by charging. I switched to "hi-pwr ohms" and the reading dropped to 4.4 ohms. Note: 412mV measured (via a DMM) across B&K meter probes during "hi-pwr" ohms reading.

It is possible that one or more of these caps is the cause of this low ohms reading (not normal). There are about 9 or 10 caps in parallel.

I will put this on the side for now, and wait for more "freedback".

Thanks in advance, John

I couldn't find a decent DC supply. Sorry.

Bill Turner. I really like his "Cease and Desist" contact cleaner formula.

How about 5VDC to 90VDC on a chip? I did some Googling and found plenty of DC to DC inverters, but I'm too busy (or lazy) to dig through the selection guides.

Yeah, I know. Every time I screw up in this newsgroup, he sends me a nasty email. Ocassionally, he agrees with me, which means I must have really screwed up badly.

He was claiming it was exactly the same as Deoxid, and got a cease & desist letter from their lawyers. Then he claimed I called them to report him. He wasn't worth a phone call. He's the Phil Allison of old radioos. Foul mouthed & short tempered. he made claims that you could make a LED flash with just a resistor & capacitor. That you could use a

All I've looked at so far fell short, at around 48 volts. Probably over 100 datasheets in that project folder. IIt's no big deal, as lomg as I finish it before I die. :)

Watch out, or he send you under the workbench to think about what you've done. Whatever you do, stay out of his stash of Corona & donuts if he does. ;-)

Maybe... While the above example can only deliver 1ma, the basic idea should scale nicely to something with more power.

More general and more interesting:

I would be tempted to take a 12v to 117VAC cheapo inverter and modify the output circuit to produce DC instead of AC. The feedback should be adjustable so that the output can be set to 90VDC. The trick is finding one that includes a schematic.

On Thursday, February 14, 2013 8:29:13 AM UTC-7, snipped-for-privacy@verizon.net wrote :

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Many Dell Pentium 4 motherboards contain bad Nichicon brand capacitors beca use Nichicon goofed up the production of models HM(M) and HN(M) from about

Some people replace conventional wet electrolytic caps with dry solid polym er caps, which are more durable in heat. Here's some information about doi ng that:

BadCaps.net not only has a great deal of information but also sells high qu ality caps.

Be careful about counterfeit caps. DealExtreme has sold them, some being p retty obvious fakes (Teapo brans substituted from Sanyo or Nichicon), and a pparently only one Ebay dealer sells only genuine caps: