a 6ya Technician can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US. click here to Talk to a Technician (only for users in the US for now) and get all the help you need. Goodluck!
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
You're either losing high voltage or power supply is not producing the horizontal drive signal, Check for 130v on the collector of the horizontal output transistor, if you're missing your voltage, you have a power supply problem. If voltage is too high you have something open in the power supply such as a low value resistor. If its low, something is shorted in power supply, possibly voltage regulator ic.
Its a common problem with this Denon model series 1508,1708,988 the trouble lies with the power supply voltage going low. Usually its either the 15 or -15 volt that goes low. If either voltage goes low it will trigger the protection circuit hence the unit will shut down.
there is a short circuit protection and overoad protection to smps so o/p capacitor may short or secondary diode may short .so check voltage at primary when switched off after 33seconds whether switching process is going or not for that check dc volt at i/p capacitor then check volt at collector of transistor if metr shows 1digit then switching is going if not then meter shows full dc volt check component near about that
It is a power supply fault. The power supply is a switched mode power supply and supplies 5 volts for the difital logic and high voltages for the high voltage parts of the tv relating to the screen display components. When the high voltage part of the circuit breaks or goes short circuit then the power supply shuts that part down leaving the low voltage rail of 5 volts..hence the standby still working. So... you need to be looking at the power supply board where the mains goes in but be aware of the mains voltages in this area if you arent experienced in electrics. The board will still hold 240v if the power supply has an open circuit load
I have not worked on your particular model. But, I have serviced many TV sets over the years. My answer will ge generic.
Check all the capacitors in the horizontal output stage and power supply areas for high ESR. All the caps that are out of spec must be changed.
The high voltage multiplier & flyback can also cause the fault you are having.
You have to consider that the DC voltages are not the only important spec that has to be met. There are also many power drive signals that work with reactive devices. If there is any defect in the critical areas there will be failures.
Check inside the receiver for a defective LM317 IC or a TIP42C transistor, but before that you should check for proper voltage from the power supply to that IC.
LM317/TIP42C control the switching of voltages that power up the LNB, you should be getting 14 volts for vertical channels and 18 volts for horizontal.
When the horizontal output (2SC4927) is shorted it means one of 2 things is wrong - the horizontal drive transformer has cracked solder joints or the flyback transformer is shorted inside. If the solder joints on the horizontal drive transformer (the small grey transformer connected to the base of the horizontal output transistor) are cracked then the set will play for a little while and then the parts you just replaced will again be destroyed. ALWAYS resolder the driver transformer when replacing the parts you mentioned! When I replace the parts you mention and I do not see any obvious cracks on the driver transformer then I unsolder the B+ pin of the flyback (labeled 135, for 135 volts) and put a 60 to 100 watt lightbulb (drop-light) in series with the flyback. This means that the 135 volts B+ goes through the lightbulb and then into the flyback, so the lightbulb acts as a current limiter to protect the horizontal output. When you turn the set on the bulb should glow no more than about half bright and you should hear the high voltage come up, but you should not see a picture. If you turn the set on and the bulb glows as bright as if it was plugged into the wall then you can bet that flyback is shorted and must be replaced.
Sounds like something is getting hot causing voltage loss or drive pulse loss to the vertical IC. Maybe you have a bad solder joint. Try tapping the circuit board around the vertical section. A capacitor could be heating and opening up.
Also you might try using circuit cooler spray and make the problem show up.
The voltage might be low because is being loaded down,open the collector of the output transistor and measure the voltage again,if it goes up to 130 or the voltage is suppose to have you might be looking at a bad output transformer(flyback)there are other parts that can cause the loaded down voltage,the yoke can be one and capacitors in the deflection circuit,check to see if one of this caps is overheated (bubble)or cook,Be carefull if you open the collector when you measure the voltage,If you can try measuring the voltage somewhere else.Lets Us know if you need meore help.
Have you checked the horizontal output transistor for a short or leakage?? most of these sets will not start up unless the horizontal sweep sends the pulse to the power supply and says start me up!! I would look at bthe drive as well on the horiz. curcuit. If theres a pulsating voltage that means its waiting for something to signal it to work or its missing something.. Good luck