REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Saturday 9 February 2019

AOC TREINAMENTO LCD TV-MONITOR _ BOARDS AND SCHEMATICS

AOC TREINAMENTO LCD TV-MONITOR _ BOARDS AND SCHEMATICS







POWER SUPPLY BOARD


POWER SUPPLY - SCHEMATIC




INVERTER BOARD - SCHEMATIC

Click on image.  Right click on the enlarged image, save image as, to a folder (My document > My  Pictures or any other). 
OPERATING CHARACTERISTIC [INVERTER BOARD]
  • When START is given on TV, the logic board via the PS sends 5V on pin 11 to ON CN902 connector with high level at the base Q934 he is so saturated with current flowing in IC934 with photo coupler activated resistance between the transistor collector and emitter decreases, thus having a voltage in the zener diode ZD933 stabilized reference point B. with the B at a high level at the base saturating the transistor Q932 have then the VCC voltage of 13.8 V.
  • Through the resistor R 907 is injected at pin 8 a voltage 160V feeding the IC 901 at initial time (start) and makes Induction that the transformer (T901) pin 2 is 13Vcc generated voltage after rectification to the pin 926 in D 1 of IC 901 (Vcc).
Pins 2 and 5 are Earth's IC.
Pin 3 CT / RT (IC oscillator)
  • Pin 4 is applied to a sample voltage (1.3 V) serves as a reference for stabilization of the pulse width PWM output pin 7 of IC 901. When the current exceeds its limit, voltage drop occurs over  920 (0.11 V) reflected on pin 6 (limiter) of IC 901, making with the IC901 remove the output pulse at pin 7, taking FET to cut off the source.
  • When the current exceeds its limit, voltage drop occurs over the pin 5 Isen (1.2 V) of the U making 811 with the IC remove the pulse output pins 1 and 15 leading FET's (Q 821 and Q 841) to the court, turning off the backlights to protect the inverter circuit
  • When there is an increase of voltage on pin 6 Vsen (above 2.1 V) due to U 811 D 853 and D 833 reflect the extra high voltage transformers coming EN 801 and EN 802 is removed from the output pulse on pin 1 and 15, the FET's leading Q 821 and Q 841 to cut off the backlights for protection inverter circuit

 With TV is off working only the power circuit board 5 volt logic.  That circuit is built around IC931.[Standby voltage circuit]







MAIN DIGITAL BOARD


Posted By: FRANK at 02:49
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