Wednesday, May 30, 2012

So, the other night we sat down to watch some Dr. Who (final stretch of the Key To Time arc in the Tom Baker era) and lo and behold, the television, a Sony Bravia KDL-32M3000, was broken.

Neil nails it at 0:37. "No more telly.."

Actually, the symptoms were highly diminished brightness with a murky red hue, the images on the screen would essentially pulse: movement by an actor would be jerky, as if watching them through a strobe light with a sort of blur between frames. It was a lot like REALLY bad animation, running dark and murky reddish images at roughly 4 frames per second. It was, put simply, unacceptable.

Suspicious that it might be the source, I went to change inputs, only to observe the sluggish response with the menu windows as well, certainly not a source problem.

Since I'm not really super keen on the whole disposable culture thing, running out and buying a new TV isn't really high on the list. In searching the model family I learned this is a very common failure mode. I pretty much followed the following tutorial, and figure I may do someone a favor with clear and legible pictures.

I took to muting the sound, as there is no narration..

I had initially planned on testing voltages between these two points, but faced with the level of disassembly I decided to just go for it. The LCD was bought new in 2007, easing my apprehension a little.. sort of a nothing to lose now project.

All those circuit boards hanging off the back? They need to be removed. Disassembly down to the LCD section is a few layers deep, I took some pictures along the way in case I had to reference anything on reassembly. The entire process was not to bad, but I've certainly been inside simpler devices.

10 ohms, tied into wire runs each end and about to be encapsulated with yellow heat shrink.

The offending ribbon connector is the largest PITA of this process. After gingerly scuffing the insulation layer with some sandpaper I folded it up and secured it with some 3/4" blue masking tape so I could solder with impunity. A bit of liquid flux was added to the partially scuffed pad to assist soldering (I feared going deeper due to the incredibly small traces, so once I visually observed a bit of metal I stopped).

With the pre-tinned wire I essentially placed the wire over the pad and directed heat from the top side. Took the better part of a second at 600f. Once that contact was made it was returned to its relaxed position and secured with tape.

The actual voltage feed I want is on the left, but the pads are close & small enough that my tinning one incurred a little crosstalk to the other.

Not what I would call a structural solder joint, that's what the tape & shroud is for..

Overall view.

While I had it apart I took a moment to admire the elliptical full range drivers that are stock in this thing. Not that the driver struck me as magnificent, just that the shape is neat enough to imagine several dozen of these in a line array configuration. No expectations...

Rainbow artifacts aside, the picture looks as good as new.


krivx said...

Kudos on the repair, and also on the Young Ones clip. Rik Mayall inspired a lot of teenage "percussive maintenance" on various devices.

crochambeau said...

Yeah, the Young Ones is in pretty regular rotation around these parts, classic.

I had to refrain from buying another broken one to see if I could fix that too; it had different symptoms, or I may have taken the plunge.