Linked by Howard Fosdick on Mon 31st Dec 2012 20:26 UTC
Hardware, Embedded Systems Last month, I explained why I use generic desktops and laptops running open source software. They're reliable and inexpensive. But this presumes you can fix them. I believe that even those with no hardware training (like me), can identify and fix most hardware problems. To prove it, here's a quick guide. Feel free to add whatever I've missed.
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Drive not spinning
by WereCatf on Mon 31st Dec 2012 21:25 UTC
WereCatf
Member since:
2006-02-15

If the drive is not spinning, most people assume it is dead. Usually, but not always. Sometimes you can get a dead drive working again by hitting it or dropping it. Freezing the drive sometimes works. Be certain you have no alternatives before trying these methods because they may destroy your drive! Prepare carefully in advance. You might only have one chance to succeed and you don't want to blow it.


If you get a drive working this way DO NOT EVER ASSUME IT WILL CONTINUE TO WORK. Copy anything you feel is important to you off of the drive as soon as possible and assume that the drive will fail completely soon.

Also quite obviously the drive should not be powered on when you try hitting it, the drive heads will hit the platters. As for freezing the drive: you don't necessarily have to freeze it, just lowering its temperature to near zero Celsius may work. The thing is that that when you freeze the drive to sub-zero temperatures moisture may condense inside the drive and then you're just worse off than you were before.

The reason for why these may work is if the oil on the bearings has gone bad and gotten crusty around the bearings -- dropping the temperature cools down the metal parts and shrinks them by miniscule amounts and therefore may set them loose, and a small amount of sudden force applied to the side of the drive may loosen enough of the crusty oil to get the bearings going for a moment longer. If the bearings themselves are gone, however, these won't work.

As always I recommend people to monitor mechanical drives' status via their S.M.A.R.T. health status and act before the drive goes bad. It doesn't always catch the issues, but often it does. I use Hard Disk Sentinel under Windows (not a free application) for this, don't know of any good GUI-application for this under Linux, though.

Reply Score: 5

RE: Drive not spinning
by woegjiub on Mon 31st Dec 2012 23:39 UTC in reply to "Drive not spinning"
woegjiub Member since:
2008-11-25

For a Linux alternative, the gnome disk checker which comes with Ubuntu works well.

Reply Score: 3

RE: Drive not spinning
by umccullough on Tue 1st Jan 2013 02:48 UTC in reply to "Drive not spinning"
umccullough Member since:
2006-01-26

Also quite obviously the drive should not be powered on when you try hitting it, the drive heads will hit the platters.


Oh? I assumed the point of hitting it was to 1) get it spinning again while powered on (this was common with older drives when the spindle motors got tired, a good thump would sometimes get them going again) or 2) to free up the actuator for the heads.

In either case, hitting it while powered should be ok, as long as you were hitting it from the side/edge, and not the top or bottom.

Of course, I would only consider such a tactic as 'desperate measures' for a disk that you had already pronounced dead.

Reply Score: 2

RE[2]: Drive not spinning
by Elv13 on Tue 1st Jan 2013 04:37 UTC in reply to "RE: Drive not spinning"
Elv13 Member since:
2006-06-12

I did this time and time again, I also suggest hitting it when powered down. I found to hit it from 5 centimeter above a parallel surface from the longer side of the disk to be the most efficient method. It work when the head or the disks get stuck. It usually need to move only a tiny amount to get freed. I also confirm that if it did this once, it will usually break again soon, for ever.

Reply Score: 3

Blown capacitors
by BrianH on Mon 31st Dec 2012 21:31 UTC
BrianH
Member since:
2005-07-06

One common problem for older desktop computers is blown capacitors. If the power supply starts but the computer doesn't, one possible cause is the capacitors failing.

You tell by looking for those cylindrical things on the motherboard that have a metallic disc on the top, usually with a cross on the disc. If the disc with the cross on it is bulging up, the capacitor is blown.

If the motherboard has blown capacitors, you usually need a new motherboard. A really ambitious tech who is good with a soldering iron can replace the bad capacitors with new ones, but for most cases it's not worth it.

Some newer motherboards have capacitors that can't blow out. In these cases, the little cylinders on the motherboard don't have metallic discs with crosses on them, the top of the cylinders is the same as the sides with no seam. If this is the case, consider yourself lucky.

You can get blown capacitors in the power supply too.

Reply Score: 7

RE: Blown capacitors
by umccullough on Tue 1st Jan 2013 02:57 UTC in reply to "Blown capacitors"
umccullough Member since:
2006-01-26

One common problem for older desktop computers is blown capacitors. If the power supply starts but the computer doesn't, one possible cause is the capacitors failing.

You tell by looking for those cylindrical things on the motherboard that have a metallic disc on the top, usually with a cross on the disc. If the disc with the cross on it is bulging up, the capacitor is blown.


Sometimes they leak out the bottom instead - you'll see what appears to be a wet spot around the bottom of the cap, usually collecting dust.

If the motherboard has blown capacitors, you usually need a new motherboard. A really ambitious tech who is good with a soldering iron can replace the bad capacitors with new ones, but for most cases it's not worth it.


Funny, in many cases, I've found the owners of said machines are glad there's another option besides "get a new computer"... and they're happy to find out that it's ~$10 in parts and an hour of my time to swap out the caps for them.

Recently, I replaced the caps on my mother's Core 2 Duo HP machine - she (and I) was dreading having to get a new machine and move all her stuff to it.

Throwing away perfectly good equipment because some company went cheap on the capacitors feels dirty to me - especially when the repair is reasonably cheap and easy for someone with basic soldering skills.

Some newer motherboards have capacitors that can't blow out. In these cases, the little cylinders on the motherboard don't have metallic discs with crosses on them, the top of the cylinders is the same as the sides with no seam. If this is the case, consider yourself lucky.


I've seen those blow their tops off too...very violently.

You can get blown capacitors in the power supply too.


I usually toss a PSU with blown caps...

Edit: bad tags

Edited 2013-01-01 02:58 UTC

Reply Score: 4

RE: Blown capacitors
by Elv13 on Tue 1st Jan 2013 04:41 UTC in reply to "Blown capacitors"
Elv13 Member since:
2006-06-12

It was very useful for big screen TV and computer LCD until they broke the price cartel, now it's so cheap it doesn't worth my time anymore. Given it only work half of the time, just buy a new one. When capacitors blow up, they often fry a few IC with them.

Reply Score: 2

The Bane of Laptop Repair ...
by softdrat on Tue 1st Jan 2013 01:13 UTC
softdrat
Member since:
2008-09-17

I recently needed to replace a dead fan in a Thinkpad laptop. Finding the right part was interesting, but found it on Ebay. Finding the repair manual was straightforward. The repair itself was also relatively straightforward except for one issue - the wires running to the built-in antennae for the wireless radios. For some reason these are draped in a somewhat untidy mess across the motherboard, held down with bits of tape. Kind of spoils the intricate workmanship of the rest of the hardware.

Reply Score: 3

RE: The Bane of Laptop Repair ...
by Doc Pain on Tue 1st Jan 2013 03:19 UTC in reply to "The Bane of Laptop Repair ..."
Doc Pain Member since:
2006-10-08

Comparable problem here while trying to resurrect a IBM Thinpad T60p: FAN ERROR, machine powers off. I've replaced the fan with a new one, same error. Because the fan doesn't even spin up, I checked voltages with a scope and could see that the power for the fan isn't present on its power pin (3 pin connector with gnd, power, sensor). Unplugging the power and carefully (!) powering the fan with an external power supply at approx. 3V makes it spin properly, and the machine boots, so the sensor tells the truth.

Diagnostic options are:

1. The wiring to the power pin is damaged somewhere. This is hard to tell when a multi-layer PCB is used.

2. The "power generating complex" (that generates all the different voltages needed inside the machine) does not provide the base voltage which is then leveled as required to control fan speed.

3. The unit that actually controls the fan speed - probably a component within the "chipset" chip - is malfunctioning.

Big question: How to find out, and how to cure it?

I'm almost doing this - and kids, don't try this at home (except you are considered insane already): Get 5 volts from a "nearby" USB port inside the laptop, apply a resistor powerful enough to bring the voltage down to 3 V (or something like that - needs testing!) and install it inside the machine. The fan itself is confirmed for 5 V at 300 mA. Close the device and let it run for longer time, make it perform hard work and be idle. Watch the temperatures (for example by using healthd and mbmon). Yes I know, resistors are stupid, a proper voltage control circuit is better. Also having the fan run all time shortens its overall lifetime. But that's still better than having bought the spare parts and now throw that nice laptop into the dumpster.

I know this is not a hardware support forum, but my problem is so exceptional that only the exceptional participants of this forum might have a pointer for me to deal with this problem-

Reply Score: 2

WereCatf Member since:
2006-02-15

Well, if you are unable to trace the power/gnd lanes on the motherboard far enough to find the culprit then your solution is similar to what I would do. I would possibly throw out the optical drive and wean the power from there instead of USB-ports, though. (I don't know if your laptop even has an optical drive or an mSATA-port.)

Reply Score: 2

Morgan Member since:
2005-06-29

I agree, tapping USB power is not a great idea. An alternative to disabling the optical drive (especially if you need it) would be to tap the extra mini PCI-E slot that most laptops have. Pins 2, 24 and 52 are 3.3 volts. Keep in mind, the second PCI-E slot may not be populated with a plastic connector, but the pads are there and should still have voltage supplied to them.

Reply Score: 3

Doc Pain Member since:
2006-10-08

I agree, tapping USB power is not a great idea. An alternative to disabling the optical drive (especially if you need it) would be to tap the extra mini PCI-E slot that most laptops have. Pins 2, 24 and 52 are 3.3 volts. Keep in mind, the second PCI-E slot may not be populated with a plastic connector, but the pads are there and should still have voltage supplied to them.


Thanks, that's a great idea and interesting approach. 3.3V should be enough voltage (maybe no resistor is needed to "slow down" the fan additionally). However, accessing the PCIe wiring might be even more complicated than connecting to USB. The only requirement left is that the power must be present as soon as the machine is powered on. I'll investigate this further - sounds possible, and I don't want to deactivate the optical unit in this laptop just to make the CPU fan work. :-)

Reply Score: 2

thx
by kateline on Tue 1st Jan 2013 12:53 UTC
kateline
Member since:
2011-05-19

Blown capacitors are common in lcd monitors as well as desktop mobos. Difficult to fix, tho.

I'm saving this for when I need it. Good article, good comments.

Reply Score: 2

RE: thx
by henderson101 on Wed 2nd Jan 2013 10:28 UTC in reply to "thx"
henderson101 Member since:
2006-05-30

Dave on the EEVBlog has covered this a couple of times:

http://www.youtube.com/watch?v=Ytw57212X2o

Reply Score: 2

Roller ball?
by Losso on Tue 1st Jan 2013 14:20 UTC
Losso
Member since:
2013-01-01

I had to chuckle. "If you have a rollerball mouse"... yeah, and how do you safely change the coal if your computer is steam-powered?

Reply Score: 3

RE: Roller ball?
by kompak on Tue 1st Jan 2013 20:13 UTC in reply to "Roller ball?"
kompak Member since:
2011-06-14

Ever heard of trackballs?

Reply Score: 2

Best trick
by martijn on Tue 1st Jan 2013 15:53 UTC
martijn
Member since:
2010-11-06

The nicest repair I did, after reading the trick on the web, was fixing a laptop mainboard with a kitchen oven.
The laptop did nothing when the power button was pressed except that the fans and the disks started running. Conclusion: defect cpu or mainboard. I replaced the cpu without result so the mainboard was the last option. A replacement costed 2/3 of the price of a new laptop. I stripped the mainboard completely, including the fixed battery, and put for 10 minutes in the oven at 200C. This fixed defect soldering connections and the laptop has been running nicely for three years since then.
My experience with defect caps is that you often need 10 of them, which are nearly as expensive as a second hand replacement mainboard. High capacity capacitors with a 10mm diameter cost two euros each.

Edited 2013-01-01 15:55 UTC

Reply Score: 2

RE: Best trick
by WereCatf on Tue 1st Jan 2013 17:51 UTC in reply to "Best trick"
WereCatf Member since:
2006-02-15

That sounds exactly like the urban legend that has been circulating around for atleast ten years now, and therefore I'm gonna call bullshit on that.

Reply Score: 1

RE[2]: Best trick
by martijn on Tue 1st Jan 2013 19:44 UTC in reply to "RE: Best trick"
martijn Member since:
2010-11-06

Did you read my post? I said I actually fixed my mainboard, not that I just read this on the net.

Reply Score: 1

RE[2]: Best trick
by kompak on Tue 1st Jan 2013 20:12 UTC in reply to "RE: Best trick"
kompak Member since:
2011-06-14

I actually fixed one PS3 found from the trash and a laptop in a similar way. However as with freezing a hard drive it usually doesn't last for very long. Especially if the machine is running very hot. In some cases it may last for years but usually just few weeks before you need to repeat the treatment and eventually it loses it effect completely.

Reply Score: 1

RE[2]: Best trick
by Alfman on Tue 1st Jan 2013 20:26 UTC in reply to "RE: Best trick"
Alfman Member since:
2011-01-28

WereCatf,

It might be an urban legend, but it sounds plausible to me. That is how they manufacture the boards in the first place. However I don't think I've ever come across any mainboards that were shoddy enough to have cold solder joints in the first place. If it were physical damage, it would be apparent on the laptop.


It's possible that the reassembly itself fixed the problem rather than the oven. Laptops often have poor connectors which might need to be cleaned and reconnected a few times at just the right angle. But in any case I applaud martijn's success.

Reply Score: 2

RE[2]: Best trick
by DonQ on Tue 1st Jan 2013 21:41 UTC in reply to "RE: Best trick"
DonQ Member since:
2005-06-29

That sounds exactly like the urban legend that has been circulating around for atleast ten years now, and therefore I'm gonna call bullshit on that.

It sounds like urban legen, but does the trick often. My colleague has restored many video cards and motherboards this way (although some of these have lasted only few weeks afterwards).
Some causes:
1. tin whiskers, sometimes building up between (and shorting) contacts, will melt
2. heat may fix cold solder joints
3. heat may restore lost contacts in some chips (old NVidia 8400/8600 mobile GPU chips come into mind)

Reply Score: 2

RE[2]: Best trick
by umccullough on Wed 2nd Jan 2013 00:40 UTC in reply to "RE: Best trick"
umccullough Member since:
2006-01-26

That sounds exactly like the urban legend that has been circulating around for atleast ten years now, and therefore I'm gonna call bullshit on that.


Bullshit or not - I may try this on an old laptop board I have that seems to have a cold solder joint issue.

It only turns on and stays on when I push down the front left wrist rest - and I've taken it down to the bones and reassembled it with no luck. I've concluded there's a short somewhere on the mainboard that twisting the case ever so slightly "repairs".

Reply Score: 2

RE[3]: Best trick
by Alfman on Wed 2nd Jan 2013 04:28 UTC in reply to "RE[2]: Best trick"
Alfman Member since:
2011-01-28

umccullough,

Hmm, that's odd. Ideally you could run it when the case is off and identify exactly which component is causing the problem. But with laptops this could be a challenge.

I've soldered a new power connector into a laptop where it had been damaged, but I'm not sure I'd ever feel compelled to stick one in the oven. ;)

Reply Score: 2

RE[4]: Best trick
by umccullough on Wed 2nd Jan 2013 04:46 UTC in reply to "RE[3]: Best trick"
umccullough Member since:
2006-01-26

Hmm, that's odd. Ideally you could run it when the case is off and identify exactly which component is causing the problem. But with laptops this could be a challenge.


Yeah, I tried to narrow down the location of the short while I had much of the machine apart, but with a laptop, it definitely gets tricky as you start pulling stuff apart to actually use it.

It's an old pentium 4 laptop anyway, so it's no huge loss, although it has a 1600x1200 screen which is what made it so compelling to utilize.

Reply Score: 2

RE[2]: Best trick
by henderson101 on Wed 2nd Jan 2013 10:33 UTC in reply to "RE: Best trick"
henderson101 Member since:
2006-05-30

Well, similar method fixed an XBOX Elite that was RROD. Reflowing the solder is a short term fix though, if the root cause of the issue isn't addressed. It's usually something to do with excessive heat and lack of cooling. The XBOX, I re-greased the CPU/GPU heat syncs and it booted and ran last time I tried it (but as we have a newer model now, it was mainly a project to experiment with console maintenance rather than anything else.)

Reply Score: 2

RE: Best trick
by umccullough on Wed 2nd Jan 2013 00:35 UTC in reply to "Best trick"
umccullough Member since:
2006-01-26

High capacity capacitors with a 10mm diameter cost two euros each.


Sounds like you're shopping in the wrong spot then...

I tend to use mouser.com, and I can usually get all the caps I need to repair a board for $15 or less (which includes the shipping).

I always order twice as many as I need anyway, so I always have spares lying around for the next project (which comes in handy quite often)...

Reply Score: 2

CD/DVD -- problem prevention is key
by benali72 on Wed 2nd Jan 2013 00:59 UTC
benali72
Member since:
2008-05-03

With CDs and DVDs I start with the assumption that the disc is the bad component until proven otherwise. Also I'd emphasize that prevention is your main goal. Treat them gently and you won't end up rubbing them down to read them. With increasing USB memory stick capacities, I wonder how long it will be til CDs and DVDs go the way of the dodo.

Reply Score: 2

howardfci Member since:
2011-06-04

True, but when USB drives fail, they really fail. At least with CD/DVDs you can still read most of your data.

Reply Score: 1

GRC's SpinRite?
by tomfin on Wed 2nd Jan 2013 14:03 UTC
tomfin
Member since:
2012-01-19

Going out on a limb and plugging GRC.com's SpinRite for clunking hard disks.

Okay, so it's not free ($89) and this is a shameless promotion - but it's well worth a shot before drastic action, like smacking the drive off a desk or leaving it in a freezer. There's always a refund if it fails to work some magic.

Since it cares not a jot about the disk format it'll operate on just about any kind of OS or data, even fully encrypted drives.

Has anyone else used it? This is just 4450 of my $0.02 ;)

Reply Score: 1

RE: GRC's SpinRite?
by Pana4 on Wed 2nd Jan 2013 16:39 UTC in reply to "GRC's SpinRite?"
Pana4 Member since:
2010-09-17

Used it many times. It can turn you into a hero when you get their data back. Well worth the money.

Reply Score: 1

Sometime it's just a mistery
by renox on Wed 2nd Jan 2013 16:17 UTC
renox
Member since:
2005-07-06

When I launch Chrome too early after the computer started, Windows XP gives me a blue screen of death quite often, if I wait some minutes most of the time it's okay.

Memtest86 shows nothing.

Note that I'm not asking for suggestions: I've given up on solving this issue, I just leave the computer alone a few minutes after I enter my password: Windows doesn't give enough enough information to help when it is crashing!

Reply Score: 2

RE: Sometime it's just a mistery
by Alfman on Wed 2nd Jan 2013 16:48 UTC in reply to "Sometime it's just a mistery"
Alfman Member since:
2011-01-28

renox,

Some hardware problems can be ruled out using a linux live cd. I follow this rule for issues I'm unable to solve:

If, after reinstalling the OS with the latest drivers, the problem continues, I assume it's likely a hardware problem. If the problem disappears, then we know it was an OS glitch.

Reply Score: 2

Tools!
by Pana4 on Wed 2nd Jan 2013 16:33 UTC
Pana4
Member since:
2010-09-17

For computers that fail to boot or bluescreen shortly after can, aside from bad RAM be a hard drive that's failing. I've used Spinrite many time to repair damaged sectors and recover all or most data before replacing the drive. Typically it will be a 4 year or older HDD or because of being dropped where damaged sectors are close together that will lock up the computer as it tries to read them.
I've replace a lot a caps successfully in monitors, tv's and even instrument clusters. A good soldering station is handy as is a solder sucker for cleanly removing bad components. I also use an in-place capacitor checker not only to test bad ones but to check the new ones before installation. I use the Peak Atlas ESR70
ESR Meter from Anatek, fairly inexpensive for what it can do.

Reply Score: 1