Tag: Element ELCHW402

Glad I could help

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I note my posts on my Element ELCHW402 repair are getting hit quite a bit. This seems to be a flaw common in the Element TV’s. But as I said, all you need to fix them is the barest of mechanical ability. If you can extract screws and open things up, disconnect connectors and then re-connect them in the proper spots you’re good to go with most televisions.

If you’re more adventurous and have the time, you can fix the power supply. Probably cost as much to replace all the capacitors as a new board. Plus you have to factor in your time too.

But you can extend the life of consumer electronics.

TV fixed!

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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

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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

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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.