Before discussing some common Television Problems and their repairs.
Here is a list of some Tech Tips related to CRT or LED/LCD Television:
- Power surges enter TV through main logic board’s audio video inputs or/and power board power cord, so check standby volts on power board of the TV, it’s either standby 3.3v or 5v dc. If OK then it might be bad main board
- Most common television repair problem is TV clicking on off caused by blown/swollen capacitors in power board, common for Samsung, LG, Sharp, Philips
- LCD TVs that have a backlight but no picture or turns off after few seconds followed by blinking red LED on TV can be bad t-con board (display timing controller) common for Sony TVs
- Plasma Television that has no picture or turns off can be bad y-sustain board and ICs on buffer board. common on Samsung, Philips, LG
- Always try power reset by unplugging all cables from TV for 5 minutes you’ll be surprised how many times that works on TVs, cable boxes, audio amp receivers, surround sound systems.
- There is a risk of shock when working on TVs, so it is best to unplug the power cord, but even if TV is unplugged it can hold juice in big capacitors so use rubber gloves.
- Always take questionable TV parts out of circuit to get best meter readings and make sure meter has good batteries.
- If TV is dead “no power” check standby dc volts on power board, it should be labeled on board “stdby” or 5v or 3.3v (mainboard plug)
standby dc volts should be 3.3v or on some TVs it’s 5v steady if it jumps 0v to 5v then check capacitors out of circuit or voltage regulator on power board, if you have solid 0 volts, check power cord for ac volts, check fuses or fusible-resistors for continuity, or bridge rectifier.
- If Television shuts down, try troubleshooting by unplugging one board at a time but power resetting in between. For example on LCD TV if T-con board is shorted the TV will force shutdown within the 1st minute as a safety feature to prevent fires. First unplug power cord then unplug T-con board out of the circuit, then plug in the power cord, if TV stays on without T-con board then replace T-con board (in few cases it can be faulty LCD panel). Also on plasma TVs try unplugging Y sustain board or Y buffer board to see if TV stays on.
- PCB printed circuit boards have “traces” lines that connect to TV part components, the board number is printed on the edge of the board or on a sticker. some boards have “rev.”#’s which is needed for the board number.
- Some TV parts can smell burnt, have burn holes, cracks on outside shell or look brownish / blacken burnt but sometimes that’s mistaken by flux paste which is used to clean and bond solder joints, flux melts when heated.
- Tapping on board with rubber handle of a screwdriver can help find bad solder joints or loose cable connections
- Using electronic freeze spray or applying hot air on different sections of boards can help diagnose tv, just check tv for any change, this works for T-con or logic boards best.
- Cleaning board cable connections with electronic cleaner can fix TVs, this worked for me on Tcon board connections.
- Novice technician replaces TV boards but expert technician troubleshoots TV issues and fixes TV boards down to component level saving 90% of the cost of an average Rs 3000 replacement board.
Plasma TV boards
Power board that supply 5v to the main logic board and x/z and y sustain boards that power the buffer boards that scan in the plasma display panel. Some plasma TVs have logic display control board. Most Plasma TV’s X/Y Sustain and buffer boards fail.
LCD TV boards
Power board that powers the main logic board of the TV with either 5v or 3.3v standby.Inverter board that powers backlight,
T-con / timing control board that connects to LCD display panel.
CCFL tubes light up LCD screen, T-con inputs images on LCD screen are some of the common parts to be repaired.
DLP TV Parts
Power board, main logic board, DMD board with DLP chip, color wheel, fans, lamp, light engine are some of the common parts to be repaired.
CRT TV Parts
Power board, main board, CT Rboard, tuner, flyback transformer, tube screen, degauss coil are some of the common parts to be repaired.
LED TV Problems
Power board, backlight LED driver board sometimes included in power board of your TV. T-con / timing control board connected to the LED display, the main logic board are some of the common parts to be repaired.
This is a tech guide, TV repair is dangerous, act at your own risk.
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