Tag: repair

Simple headphone repair

So I’ve got a pair of Subjekt headphones that I REALLY like.

Image

They sound FANTASTIC. Put it this way with some inferior brands of headphones I found myself having to crank the volume pretty high. This one, 1st or second bar it plenty loud enough.

But I sat on them by accident and broke the screw mounts on the right side. But hot glue to the rescue – I just put a dab on the three stumps and mashed it together and presto, headphones repaired and functional for another day.

Didn’t have to re-wire anything which was very nice.

Fixing ancient laptops

I’ve had this laptop for a long time. I’ve done preventative maintenance on it and repairs where necessary.

One of the things that drove my nuts about it was the screen hinges. The things were just worn down, the screen would flop any which way.

Searched the web and found a new set of hinges for $10. It took the removal of 12 screws to do this, the ones on the screen surround, and the screws holding the hinges to the rear of the display cover and those that secure the screen to the chassis of the machine.

And as I’ve said – I understand the limitation of XP and 32 bit architecture. But it still does what I need it to do without any major issues. And I was of the firm impression that Vista was a piece of crap, Windows 7 was acceptable but unnecessary to upgrade to that as it was a bit bloated, and Windows 8 looks like it was designed by a crack addled ADHD sufferer. And that’s me being nice about it. In my opinion XP was the pinnacle for Microsoft. And it’s been down hill every since.

What Microsoft doesn’t realize is this:

1) An operating system has a very LONG life span. And just shoveling new OS’s out there that in essence were half baked pissed a lot of people off.

2) The cycle for I.T. infrastructure isn’t two years, it’s more like 4-7 years.

It is entirely likely that my next computer will not run Windows. Or at least not as the default operating system. Instead I’ll probably get use Debian Linux and VirtualBox on it. VirtualBox is a virtualization package that lets you run another OS image underneath the main OS. So I’ll just clone my current XP box into an image and use that when I need to get access to MS Office, etc.

And I will kiss goodbye forever Microsoft’s craptastic operating systems. Yes I said it, I’ve dealt with Windows for over 20 years now and all I can say is that it’s been one pain in the ass after another. From print drivers that no longer work with the latest versions of Windows, to bad file system structure, etc.

Linux at the very least is flexible as hell. The ext4 file system can have drives up to one exbibyte (EiB). That’s that EiB is 1 exbibyte = 260 bytes = 1152921504606846976bytes = 1,024 pebibytes. A pebibyte is is 250 bytes. And right now we’re only seeing terabytes and gigabytes. So there won’t be any problem with big files in the ext4 file system.

Plus ext partitions have journaling capabilities, error correction, etc. Compare that to the Windows File System.

I can just use Macrium Reflect to create the boot image of this machine – and BAM! Virtualized in style.

So I’ll be leaving Microsoft for greener fields. And in fact once I image this machine I’ll probably put Ubuntu or Debian on it. It’s still usable.

 

 

 

Older Laptop Repairs

I’ve kept two Dell XPS M140’s up and running for close to 8 years now. I see no reason to upgraded as yet as these computers still have life in them.

The other day the lamp on my LCD went. Ok – $133 got a brand new LCD with inverter and lamp 2 day expressed to the house. Only had to remove 18 screws, the hing cover and the frame around the screen to do it.

Then I had to salvage the cable from the old LCD – but I could not get it to plug into the new screen. That’s because the new screen has a shielding hood over the connector. So I just peeled off the shield on the plug and all as well.

Then put the 18 screws and the hing cover back on and voila ! I saved the old screen – it works. Just has no light. But here’s the thing, if you tear into it I can remove the inverter and lamp and maybe replace with an EL panel or LED’s and then use it on a project.

I did note that the hinges on the screen – the left hinge is cracked. So I ordered a new set of hinges.

TV fixed!

So when my Element ELCHW402 gave up the ghost I said it was the power supply – yes indeed it was. However I did a quick bit of math and figured out that for me to troubleshoot the power supply would take inordinately longer amounts of time than to just search the board number. What I’ll do is havest (and test) parts off the old power supply board over time. That way I’ll identify the common failure nodes.

So I did, and the best price I found was $69 from Sears Parts Direct.

I had ordered it two weeks ago and on the 11th I checked the tracking information and noted it said it had been delivered. Now it’s a good size box, not one I could easily miss but it was sent via SmartPost which is hit or miss.

I called Sears Parts Direct and emailed. In the email I told them I’d noted it delivered but never received and that if no response within 7 days I would move to have my bank charge back the purchase.

But the call was more productive. I was told I’d have the part by the 14th and sure enough, UPS shows up today with it at 12:25PM.

I installed the board and pressed the power button and wonder of wonders I saw the little blue “Component” banner pop up and then a blue screen with “No Signal”. She works!

You can repair consumer grade gear – you just have to be in possession of the skills to do so. A screwdriver (philips, straight edge, torx, hex), a pair of pliers, a multimeter or two, and the gumption to tear it apart.

That last part is what stops a lot of people. It’s easier for them to go out and buy a new television at several hundred dollars, than to spend around $70 and effect the repairs themselves.

We’ve become such a throw-away society. But not me – don’t throw it away, take it apart!

Now I just need to put the case back on but I’m leaning toward leaving it off. It’s how I ran my early computers – covers off. Never know when you want to fiddle with something inside.

My diagnosis was correct

I opened the TV up and extracted the power supply board. On close examination I spotted this:

The Bulging Capacitor

Electrolytic capacitors should have a nice flat top surface. When they bulge it indicates excess pressure within the electrolyte. When that happens the capacitor doesn’t work so well.

And as I explained here, ripple isn’t good for 5V and 12V electronics. Now I’ve banged together 125VDC supplies to trigger a coin relay on a pay phone, so ripple doesn’t matter as much. But discrete electronics want a constant voltage and current in many cases. And ripple plays havoc with that.

I’m so glad I have the knowledge and experience to be able to take things apart, identify faults, and fix them. That all started with my great grandfather, he’s the one who taught me how to solder wires together at the tender age of 6. My great grandfather was also an engineer himself – and one of his sons was also an engineer. So on my mom’s side of the family – it was a pretty sure bet I’d pick up some engineering skills.

Uh oh – Element ELCHW402 TV has given up the ghost

I bought this in December of 2010 – so here we are a year and a half later of constant use and came home today to a red light on the front of the unit but it won’t power up. Soon as I saw that I knew what it was.

Of course because the standby is a the red light Keyron was all confused. I finally convinced him that it is the power supply for the television that is having issues. This is a common failure mode on virtually every HDTV set out there.

The issue will delve into electronic theory just a little bit.

AC line voltage here in the U.S. is nominally 110V AC (Alternating Current) and can go up to 125V AC (Which it is where I live).

If you were to hookup an oscilloscope to the AC line you’d see something that looks like this:

Sine wave

Now the terms on the image change ever so little on the scope, the Amplitude side is the voltage, and time remains constant.

Electronic logic doesn’t play nicely at 125V AC. So what you do is use a transformer to step it down, then you use a thing called a bridge rectifier. A bridge rectifier makes a semblance of a DC voltage but with serious amounts of what is called ripple.

This image shows the effects of rectifying the incoming current:

Ripple Explained

See the bottom of that image? The voltage rises and falls multiple times. To smooth that ripple out you use capacitance. A capacitor is a device that stores charge electrically. It’s usually comprised of two plates, separated by some dielectric, in many cases air.

And it’s job is to store up current quickly, and release it to smooth out the dc voltage.

In the case of the television we have, they use electrolytic capacitors:

Electrolytic capacitors

You’ll note there are two values on an electrolytic capacitor that are key – the capacitance which is measured in microfarads, and a voltage rating.

Manufacturers of HDTV flat panel LCD sets are notorious for using capacitors with too small a voltage rating. And when the filtering goes kaput, the television will NOT power up.

The solution, at least 99.9% of the time is to yank out the power supply board, get all new capacitors of the same microfarad value but in a higher voltage level. And it’s good not to get Won Hung Lo capacitors from China. Get good ones, quality ones. You might spend $20 or $30 on parts. Labor is probably 2 or 3 hours. Now in my case I know my labor rate, it’s $50 an hour for electronics work so $150+$20 = $170 to repair the set. As opposed to spending $300, $400, or more to replace it. You see what I’m getting at here.

So tomorrow I’ll tear it apart and then get online at mouser, Allied, or any of the big electronics distributors and order the capacitors to replace. I’ll also be able to do a visual inspection and see if there are any bulging capacitors in there.

I’m so happy I know how to push electrons around. And come to think of it, we probably experience a power spike, what with the vicious thunderstorm last week. That would be enough to push a weak capacitor over the edge.