Recovering Linux – 4

This is the fourth installment of a series of posts to document “How I recovered my Linux systems…”  See the first post and second post for the preliminaries, and the third post for diagnostics and disassembly…

Okay, I think I’m ready to power-up my repair-in-progress system.  However, whenever major PC surgery is underway, checking things more than twice is a good idea.  All disconnected cables and signal wires back in proper place?  Loose cable bundles tie-wrapped to something secure?  All screws, er, screwed-in and tightened?  All screwdrivers and stuff out of the box?  All fans unobstructed, and air-flow paths clear so cooling can happen?  Check… check… check… and double-check.

At this point, most folks would replace and secure any enclosure panels and reconnect things like mouse, keyboard, monitor and power cable.  But here, just to be sure that everything’s electrically ready to go, I decided to just plug in the power and do a quick power-on sanity test, just to see fans spin and internal LEDs light up — this would assure me that I’ve got everything hooked up right.

So… carefully!  I plug in the power cord to the rear-panel receptacle and to a handy UPS (uninterruptible power supply) and, gingerly… press the front-panel power button.  Ta-da!…

Nothing… Nada.  No fans spinning, no motherboard LEDs light up.  Acts like a dead-duck.  Crap.

Be careful here.  Think!  And I was careful… I know that the only things that I disturbed and worked with were the disk drives, and the SATA and power cables that attach to them; there was no need to mess with anything else for this exercise.  And I know that, prior to opening the enclosure, the box did at least power-up, even with the failed drive.  So, what did I miss?

Modern (and maybe even older) PC motherboards have several “fail-safe” interlock circuits, things which sense voltages-in-range, spinning cooling fans, and even derive overheated component temperatures, all to shut things off, or turn ’em off, if something goes electrically bad.  Unfortunately, these interlock circuits consist of very small-gauge wiring which hooks up to on-motherboard connector pins, color-coded but otherwise unlabeled.  Hard to see, harder to trace.  Had I accidentally managed to dislodge one of these?

Finding out took a flashlight and some careful shifting and lifting of the power cabling which overlays and obscures the box innards… Short story is that, yes, I’d managed to unhook one of these little wires — it was difficult to see, but there’s the loose little culprit, and fortunately, it was dangling right over the pin that it should be connected to, and it’s also one of a twisted pair of wires, with its mate still connected to the pin adjacent… Sufficient for me to be confident that reconnecting it — to that pin — was the right thing to do.

Once reconnected, repeating the power-up test was successful: fans spinning, motherboard LEDs lighting up, disk drives spinning up… enough to tell me that I’d done some good — and no damage  — so far.  Power-down immediately.

Now’s the time to put the enclosure skins back on, turn the enclosure over onto its feet again, connect mousie, keyboard, monitor and power cord, ready (with some confidence) for full power-on.

But wait-a-minute, now… What software’s going to boot?

Remember, I’ve now replaced two disk drives, one fully failed and the other which should still be a-okay, with one much-larger 2TB disk — and this new disk drive is “naked” out-of-the-box.  No Linux, no data… it’s not even “partitioned” yet…

Next post: Partitioning the new disk drive for Ubuntu/Linux…

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6 Responses to Recovering Linux – 4

  1. I was just doing some surfing on my Nokia Phone during my spare time at work , and I happened across something I thought was intriguing. It linked over to your site so I came over. I cant really figure out the relevance between your site and the one I came from, but your site good none the less .
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  3. Lorin says:

    Thank you for your encouragement and kind feedback. Hope you got to read through the whole series, and I plan to do more of this kind of article, esp. if there’s demand for it.

  4. Lorin says:

    I plan to do more of this sort of writing, especially after my current job hunt ends successfully. Thank you for your kind remarks.

  5. Pingback: Recovering Linux – 6 | The Rockjack

  6. Pingback: Recovering Linux – 5 | The Rockjack

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