Monitor died...might be repairable by someone braver than I

[Vince]

Looking at the following thread I suspect it is a few bad capacitors in the monitor.

Anyone game to give a go and see if they can repair?  I am interested in learning to myself but not interested in electrocuting myself.

http://www.badcaps.net/forum/showthread.php?t=19880

it is a Hannspree HF 289H.

Let me know or off to recycle it goes.

Thanks!

Vince

[Jim S]

Electrolytic capacitors are often the parts that determine how long a thing works.  As a first step I would look at the capacitors carefully and look for bulged tops.  If they are bulged then replace them.  Beyond that is more complicated but the other forums may tell you which parts typically fail.  I have repaired several things just by replacing caps but don't have time to take on this.  Maybe someone else will take you up on this.

[EschewObfuscation]

A device you are willing otherwise to recycle is the definition of "no courage required"; it's not a multimillion dollar mainframe you might damage.

Should you attempt the task and fail, all you could possibly suffer is a few $ wasted parts (probably less than 10), and possibly a popped circuit breaker and snootful of magic smoke, worst case. and it might work.

Not all bad caps are necessarily visually identifiable, but most of the time, bad caps are indeed the culprit; consumer goods usually use cheap, shoddy ones. So open it up, write a list of all the values and voltages of the electrolytics, place an order for replacements (I like mouser.com, but digikey.com is a possibility as well), choose LOW ESR for all of them, try swapping them out. You have better than 50/50 chance of success, and it's a cheap adventure. My advice is give it a go, the down side is limited and it might work. And you get massive geek cred if you luck out! :)

[Jim S]

True that the bad parts won't always be bulged but true often enough that it is a good first step to see whats bulged. 

There is a shock hazard since from what I read on the linked site there is a high voltage bus of about 300V.  Usually this will discharge after a few minutes of unplugging but worth checking and taking some precautions.  If you can access the terminals it's easy to measure the voltage with a volt meter.  When things fail they don't always discharge as intended. 

As was stated the cost of the parts is very low so if you want to learn this is a good candidate.

[EschewObfuscation]

In theory there is a shock hazard, though nothing like the old CRTs; 300V biting your finger is an owie rather than a heart stopper. So some caution is sensible, but fear really isn't. Especially since the odds are the cap that failed is in the inverter circuit, and most likely shorted it the moment it failed.

Back in the day when I salvaged bits from old CRTs, I'd just park em in the bathroom before I took a shower, on the assumption the steamy air would encourage any necessary tube discharge. I never got a pop when I performed the discharge ritual anyway. Pat it down with a rubber glove and wad of steel wool if you like, caution doesn't hurt, but I doubt you'll find any residual voltage, especially if it's been unplugged a while.

[Jim S]

I don't want to freak out the original poster as these things are not terribly dangerous if basic precautions are taken...

Steel wool is a pretty poor idea, IMHO.  For one thing, if there is significant energy stored in the caps the steel wool will melt with a bang faster than you can pull your hand away.  Youtube is filled with impressive videos of blowing up wads of steel wool with charged caps. Here is even a school lab for it:
http://www.oberlin.edu/physics/catalog/demonstrations/em/capenergy.html
I will admit that many use more capacitance and/or higher voltage than you will find in the average solid state monitor - but the joules of energy in the lab isn't that large and could be present in a monitor power supply.  There are better ways like using a resistor or just using a meter to confirm it is discharged, which it probably will be.  Also the steel wool could leave hairs of steel in the circuit which could cause all sorts of trouble. Lots of very small pitch surface mount ICs in modern equipment that are easily shorted by very small bits of metal.  

[Brad Tissi]

I wouldn't stress too much over it.

Buy better replacement caps, make sure to line up the stripe on the cap to whatever indicator should be marked on the board (or mark it from the old cap with a sharpie if in doubt), replace any suspect caps.

I usually set the pcb upside down on blocks, use pliers or vice grips to veeeeeery lightly tug on the cap while melting the solder. Put the leads through the holes slightly spread to hold it in place, add enough solder to flow through the hole, but not enough to overflow. It really doesn't take much solder.

I've done this for many a lcd.

[Jim S]

Desoldering may take a bit of finesse or 3 plus hands and two soldering irons.  With just one iron and without help one lead can be heated and the cap tipped to pull that lead part way out of the board.  Do it gently to not rip the metal barrel out of the plated through hole in the PC board.  Then heat the other lead and rock it the other way.  You probably won't be able to get it off with only one heating of each pin.  It will take several repeats.  Or get two irons and some help to heat both leads at the same time and pull it off.  Clean up the holes with solder braid or a solder sucker and put the new cap in.  Note the polarity as Brad said.

[eAddict]

This sounds like something I should bring to AR to work on...

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[EschewObfuscation]

gah, 4kV caps for a flashy physics demo is a whole other kettle of fish. I'd not worry about theoretical iron hairs either from patting down a board, not scrubbing it, but you could use a coarse copper pot scrubber, or the wad of turnings from a soldering iron tip cleaning pot if the prospect worries. Personally, I don't think any of it's necessary if it's been unplugged for a while.Has anyone here ever been nipped by an LCD board cap?

[EschewObfuscation]

Oh! Sometimes things just have to percolate about in the back of one's head for a bit.

Just stab about with a bit of conductive foam. Meets everyone's objections. If you think the exercise is necessary at all...

[Jim S]

Depends on who is there at the time but I think your chances of finding someone who can help are pretty good.  Seems like a good plan.