One of the most common faults we see today stems from failure of the LED backlights and results in symptoms of ‘sound no picture’. This can easily be distinguished from a faulty T-con by shining and angling a bright light close to the screen. In cases of LED failure a faint picture should be visible on inspection. It should also be noted that a faulty power supply can also cause the same symptoms.
Most LED sets contain multiple strips each with numerous individual bulbs. In order to repair this fault it’s necessary to determine how many strips have actually failed (and so won’t illuminate at all) and how many have shorted (dead) bulbs. Depending on the make and model differing sets have a different tolerance in terms of the number of failed bulbs they can accommodate before the array will no longer be lit.
LED failure seems to be common across all LED sets, however from our own experience we’ve seen it far more commonly in the Vestel 32″/40″ sets (Hitachi/Toshiba/Panasonic/JVC) as well as the LG 42″/47″ models. We rarely see this fault in Sony sets (which happily have their own set of issues) but this may just be down to what we’ve had the opportunity to see.
LED replacement is a considerable job to undertake due to the various steps involved and chances of irreparably damaging the set. Most notably of risk is the chance of cracking the screen on removal/replacement or damaging the sensitive foil tabs connecting the T-con.
- Strip down set
- Remove screen and lightbox filter layers
- Test and mark faulty strips
- Replace all strips with faulty bulbs
- Test array
- Reassemble and test set.
- Apply any updates and alter backlight settings to prolong set-life
Throughout all this care must be take to ensure dust and general debris does not get trapped between the lightbox layers, marking them while the set is stripped down awaiting parts.
Some repairers **COUGH*ON YOUTUBE* COUGH** prefer to replace all individual failed bulbs by hand using an SMD rework station to keep costs down. We’ve tried this approach and while fairly reliable the time involved and chance of individual bulbs appearing brighter and remaining visible after reassembly makes it impractical for the number of repairs we undertake.
We always prefer to replace all strips that have failed bulbs with fully working replacement strips. We occasionally have customers ask if we can provide a cheaper repair by replacing perhaps only half of the faulty strips, just enough to get the sets working again. Due to the risk that the set would fail again under warranty should any further bulbs go down (and therefore be a massive pain to sort all over again) we only carry out LED replacement providing it will bring the entire array back up.
In short LED failure is a fairly common fault appearing in numerous makes of TV. With the correct parts available repairing failed sets is a relatively simple process. Disregarding any parts the main cost of such a repair is the technician’s experience in accessing and replacing the failed strips and the necessary time in doing so. The cost of course varies depending on the number of failed strips and this in turn require the set to be fully stripped to confirm.
If you think your set may have this fault simply drop it in to us for an entirely free estimate on repair, or fill out the contact form to the right.