Televisions

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General Problems[edit | edit source]

Problem Solution
TV won`t power on. Standby LED blinking.
  • Mostly when the standby LED is flashing, the problem is with the power supply. Check diodes and capacitors, as they are usually the cause of this behavior.
  • Sometimes there can be a problem in the TV firmware; in this situation it is necessary to reinstall the firmware and it is desirable to replace the EEPROM
TV won't power on. Standby LED behaves as expected (on when the TV is off, then off when the TV is turned on) but the TV screen will remain off.
  • This is most likely a power supply failure. It could be a faulty capacitor. This symptom indicates the TV has enough energy for standby, but not for running (especially the display, that is responsible for most electrical consumption). A good troubleshooting step for this is to connect the TV HDMI output to an equipment that can read the EDID information, and see if any information is communicated via HDMI.
TV has sound but no image. Backlight not working.
  • Can be that one or more LEDs in backlight strip is broken, check each LED in strip (start with 2.6 V or 5.7 V PSU, or use the diode check on a multimeter) you can replace the LED that is broken or replace whole strip.
  • Can be that PSU is problem, if LED in strip is good, then is LED driver in PSU unit, depending on the manufacturer, there are kit components for LED driver in PSU unit.
  • Can be the backlight inverter. Beware of the voltage it is meant to output, which is easily above 500 V. Use proper equipment (at least rated 1000 V) when testing it.
No sound
  • Check volume, sound settings, and cables.
  • Unplug television, hold down power button on television for 30 seconds, then plug back in.
  • If problem persists, check if the television has an update available or reset television to factory settings.
  • If issue keeps occurring intermittently even after restoring to factory settings, some televisions have a "quick start" mode (standby mode) option where pressing the power button doesn't turn the television off to provide a faster bootup time. Change this setting to full shutdown mode.
TV stuck at Boot Logo or Black Screen
  • Some cheap TVs like Grundig, Telefunken, Dyon, JTC and Kendo (Mainboards made by Vestel) are using a Firmware that tend to self destruction, try to find the correct Firmware for the Mainboard and flash it by using an external Programmer.

Samsung UE... TV click-clack on-off loop[edit | edit source]

Problem Solution
Device can be switched on with the remote control, relays for main power supply click on, splash screen appears. A few seconds later the main power supply clicks off. After a few seconds the main power supply clicks on again and the whole process repeats indefinitely.


Device can be temporarily "fixed" by bumping on the back of the device in certain locations, indicating an intermittent contact issue. But the problem will re-appear after a few minutes.

This can be caused by a loose cable between power supply and mainboard. The cable is longer than needed, which can result in stresses due to kinks?
  • Remove power cord
  • Remove screws that hold in back metal cover
  • Remove back metal cover
  • Visually inspect electrolytic capacitors (if they look like new, the fix may be very simple)
  • Carefully unplug and re-plug the connectors of the cable that connects the power supply unit (e.g., L46X1Q_DHS BN44-00623B by Hansol Technics Thailand Co. Ltd; right-hand side) to the logic board (e.g., HIGH_X12_UNION, Model: BN41-01958, Code: BN41-01958A, left-hand side)

Sony Bravia Screens[edit | edit source]

Problem Solution
Screen does not power on, red light flashes 4 times This error is generally to do with protection related to overheating. Either the PSU is overloaded, the backlight powersource/inverter is drawing too high a current, or a temperature sensor / related sensor has tripped
  • Lie face down on a towel, remove bottom stand such that screen lies flat on towel
  • Open rear and remove dust from PSU board. Careful any charged caps
  • If very dusty, remove PSU completely and dust with a brush (especially backside)
  • Ensure MOSFETs and diodes connected to heatsinks have thermal paste and are tightened accordingly
  • Replace any swolen caps on PSU
  • If it is a plasma backlight model, check the high-voltage connector plug between PSU and Inverter. Clean inside of plug ends with contact cleaner. Ensure cable is secure.
  • Check all axial fans that have 3 wire leads. If the mainboard detects RPM of any fan is too low, it will trip as an overheat warning. Replace fans if necessary
  • On completion, reassemble case. Hold down Power button and Volume Down button and keep holding while you plug in the power cord. The light should flash green indicating a reset has completed successfully

PSU Problem[edit | edit source]

Problem with Vestel 17IPS62 Solution
TV has sound but no image. Backlight not working.
  • LED Driver in PSU is problem, if LED in strip is good, then is LED driver in PSU unit, check for short on Q4 MOSFET and U5 led driver IC for Vestel 17IPS62 replace C113 cap, D10 diode, Q4 mosfet, U5 led driver IC.

CRT Televisions[edit | edit source]

Note: CRT TVs and monitors contain high voltage equipment that MUST be discharged properly before work is to be done inside the television, the tube can contain a lethal charge that can kill or severely injure you if you do not discharge it properly.

Problem Solution
Video unstable / out of focus / dim / non-existent but high voltage is still audible.

Especially if adjustments to focus / color / brightness knobs on the back of the TV effects image.

Fig 1: Neck Board Diagram
  • Most likely a problem with the CRT neck board (check image)
  • Unplug the TV, open the TV, properly discharge the TV, locate the CRT Neck Board
  • Gently wiggle the neck board off the electron gun (remove cables if necessary, depending on model)
  • If necessary (depending on model) remove shield or encasing around the Neck Board Look for any cracks or weak solder joints in the Neck Board. See Fig 1.
  • Test all traces and connections with a multimeter
  • If any cracks or weak solder joints are found, bridge / repair them with the method of your choice
  • If no cracks or weak solder joints are found, reassemble the TV and test it to see if reseating the Neck Board helped
  • If that does not help either, there may be a different issue with your television.
  • If the issue is out of focus or dim image, the issue may be fixable by adjusting the focus and brightness internally via knobs on the transformer. On most CRTs there are 2 knobs on the side of the flyback transformer labeled "Focus" and "Screen" (In some cases horizontal and vertical focus will be separate Pots)
  • "Focus" adjusts the focus (which will be the size of the "dot" on the screen that draws the image) "Screen" adjusts the brightness of the screen.
  • WARNING: for best results, these knobs need to be adjusted while the CRT is turned on. Use non-conductive screwdriver to turn knobs, stay isolated from ground and do not touch or get near any part of the tube, or circuits surrounding the flyback transformer.
  • Put a good test image on the screen and slowly adjust the needed knob until you get a desired picture.