I have good power supp.,good fuses, and no bad solder in board,no apparent heat or smell. I have power @ switch,at least the light is ill. as soon as you plug the unit in, and you can hear a faint clicking sound for a sec. as if a cap is storing power. But no pic. or aud. Why is power indicator on before I push power button? No change after pushing power button.
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Re: No picture or sound.
How do you know the power supplys good? Its probably whats always bad on these sets. If the horizontal output is shorted, the flyback is also bad. The the HOT is not shorted, take a scope and on plugging in the set make sure you have a drive waveform, at least 3 to 6 Volts PIV. If you have all the proper tools and equipment, this is an easy set to troubleshoot. If you dont and trying to fix it with a multi-meter alone, Sorry is'ent going to happen. A TV set is not a place to go into and experiment with. Its a solid state set so there are no user serviceable parts inside. Please! Take this set into a pro to be diagnoised and serviced before you end up hurting yourself and or causeing much more damage to the set then there already is.. Good Luck
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With volt-ohm meter (vom) check for 24v input power. Most output voltage will be 5v DC, check for that. If the relays are soldered on to the board, your only solution is to replace the board. A "ticking" sound may be a bad relay. One check you can make is to disconnect any incoming power to the unit and remove the board. Inspect the soldered side of the board, if you see any black or brown spots, most likely the board is bad and will need to be replaced.
Before you spend a lot of money, try checking for these:
- poorly soldered or partially desoldered wires, connectors (power, signal input) or ANY other components (especially the ones that tend to heat up, like power transistors or voltage regulators - a component which has been heating up will cause the curcuit board around it to become somewhat darker)
- dirty or oxydized contacts on ANY of the connectors or switches
- partially or fully blown electrolytic capacitors (see if any are damaged, bulged or blown at the top, these surely need to be replaced)
- internally damaged tantalum electrolytic capacitors (probably there will be no apparent damage to these, but they may cause intermittent disturbances if they are bad).
It may as well be something else, but if your equipment was being used extensively during these 6-8 years, it is likely that some capacitors may have dried up or otherwise failed.
It is also likely that the sound vibrations caused loose connections or bad solder contacts on the circuit board since it is a powered sub with an integrated amp (many audio devices get to suffer from bad solder contacts just by heating up with years of use and even without being exposed to powerful sound vibrations).
Hi! In most of the cases, this is usually due to a bad magnetron, the other time is sometimes a bad high voltage diode which you have already replaced. Most of the common things are....loose high voltage wire.....poor solder joint on board.....magnetron.....power relay or a bad door switch. Other possible problems are a faulty relay or solder joint on the power module, but a bad door switch is most common. Please check all these to resolve the issue you are facing with.
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CHEAP TV VIDEO REPAIRS Can't be 100% sure but the most likely cause of the problem is bad solder connections in the switch mode power supply or on the vertical output IC, or anywhere on the main or picture tube circuit boards, due to age and switching on and off TV's develop bad solder connections when cold the connection is made and when it warms up due to heat expansion the connection breaks, you will need to be handy with a soldering iron, and discharge all power supplies with something like a 100 Watt globe before soldering or you may blow things up and do really serious damage, and be warned TV 's have very high voltages 360 volts DC in the SMPS primary and over 20,000 volts to the picture tube, so be careful.
Best first step is: Good visual inspection = look for hot spots
on PCB, check caps in those areas + solder any/all bad connections,esp. low voltage regulator pins.Look the whole
board over with magnifier = solder,solder,solder...T.