LE32B530P7NXXU CCFL tube replacement project

[monstermonkey]

I've got a LE32B530P7NXXU (NOT the WXXU with the Analogue only issue) that I picked up with broken CCFL tubes, LCD panel itself is fine.

This set uses 8 U shaped CCFL tubes for the backlight, 6 of them were smashed, I tried finding some replacements but I couldn't find any direct replacments off the shelf, the ones I could find of a similar size (non U shaped were very pricey.

I got my thinking cap on and figured some decent LED's would backlight the screen, just like the modern stuff so set about finding something suitable, after a good google session I found a Chinese supplier of LED tape, 5 meters in length, 300 LED's per 5 meters, spaced evenly at every 17.5mm, wide angle (120 degree) light output and powered from 12 volts (each LED has a resistor)

After carefully removing the CCFL tubes and disposing of them nicely, I waited for the LED's to arrive from China, £18.99 per 5 meters delivered - 2 weeks later they arrived and I set about fitting them.

I actually used 15 lengths of them to mimic the 16 CCFL tubes location, I originally diasy chained them together, but suffered the inevitable voltage drop accross the run, so re-wired them in parallel, the light output is fairly even now.

I reassembled the panel, hooked up the mainboard/psu and inverter (set wont run without the inverter) and powered it up - quite a decent image, comparible to the CCFL tubes.

I just need to work out how to fake a power good from/to the inverter board (as I will be removing it)

The image is good, but you do get feint banding, it needs more rows of LED's - one of the problems using the China LED's is that one of the rolls changes colour half way through at a join - from cool white to warm white.

Pics below of my hair brainedness, it might sound like a lot of effort to get a TV going, but I've saved an otherwise scrap 1080p panel.

If anyone knows how to force the inverter power good I'd love to know.

I've got another thread about an LE32 with analogue only, sadly the 2 sets are very different inside and the mainboard won't swap over.

[Turnip]

Hi M/M,

Really impressed, guess those LED tapes you used must be intended for that sort'a purpose. Think to stop saving all those CCFLs recovered from sets with serious Wii Attack.

Wonder about the difference in power consumption - LEDs have really come on a bit since we needed a torch to check if our Sinclair digital watch was really keeping time.

Nice one - Chris.

[monstermonkey]

Hi Chris, I thought that may tickle you.

The LED tape seems to aimed at interior designers for posh lighting, but just so happens to be ideal for this purpose, wide angle, highish output and lots of the little things, evenly spaced.

I hadn't thought about asking about used CCFL's, didn't think anyone would delve that far into a set on a salvage mission - should have known better I guess.

When I get chance I'll pop a meter in the mix and get some current readings, but my spidey senses tell me the current draw is much lower than the inverter/CCFL route, due to lack of sparks when hooking up the power source (salvaged SLA battery from the kids leccy scooter haha), unlike the inverters that give a visual idea of their current requirements when hot plugged.... 

Don't get me started on Sinclair stuff, childhood memories of a house full of calculators being built/repaired by home worker parents... enough to make one shudder.

Anyway, now I've proved the theory I'll dial out the glitches and polish the design, don't think I'll be going the sector addressing route like the makers do though.

Cheers

Andy

[Turnip]

Hi M/M

Was thinking about those small screen sets that use a solid perspex edge lit panel with CCFLs top (and if you're lucky, the bottom as well)   Had several in with infamous Vestel 17IPS series Power/Inverter where the tubes seem to die prematurely.

Found a large'ish  'Picture frame' at the tip that used a string of really tiny leds at just the top that lit the panel really well.

Got to be cheap though, new small stuff at Tesco does everything for £60,  lasts a year - there's points too, and in late 2011 will be found at Council tips, minus the RCU - Ah well, at least we don't have to find up an in-line P/S - Just a customer who doesn't shop at Tesco (think to drop flyers at the Co-oP) - Chris.

[monstermonkey]

Hi Chris,

I did see a page on the web where the poster had a cheapo LCD monitor that had a duff CCFL tube and he replaced it with some LED's - the old fashioned ones, it involved plenty of drilling and some hot glue but seemed to work, another project I saw (Apple iBook) gave similar results, but with some "theatre front row" lighting effect at the bottom of the screen, presumably due to poor or missing light dissipation material.

I put a meter in the mix and saw a current draw of 3.1 amps @ 13.5 volts running 630 LED's, I've finished the set now and am using a re-purposed 24v to 12v dropper from a truck to utilise the 24v rail for the inverter - I found that simply unplugging the inverter board was sufficient to get the set powering up, I didn't fancy stealing 3.1amps from a 12v line, Sammy PSU's seem a little marginal at the best of times.

This Sammy doesn't seem to mind in the least that the inverter board isn't there, although the 'backlight' software control doesn't do much these days, just moving around the screen with no effect.

I reckon you'd get 8-10 smaller sets working from a 5 meter reel of the LED tape and claw a few quid back on the redundant inverter boards.

[Turnip]

Hi M/M,

Notice that you said that diodes had individual series resistors.  As high brightness leds seem to like 6 volts  for some reason - guess there's some 50% waste, powerwise.

Got my new, on line Scot Power stuff today - think Norfolk turkey/candles - bright but ever gobbling - Chris.