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!

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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Wednesday 13 March 2019

JVC LT-42P789/C SERVICE MODE AND POWER SUPPLY CIRCUIT

JVC LT-42P789/C SERVICE MODE AND POWER SUPPLY CIRCUIT


JVC LT-42P789/C

 LCD TV

SERVICE MODE AND POWER SUPPLY CIRCUIT


SERVICE MODE
HOW TO ENTER THE SERVICE MODE
(1) Set to "OFF" using the [SLEEP] key.
(2) While "OFF" is displayed, press the [V. STATUS] key and [DISPLAY] key simultaneously.
(3) Enter the SERVICE MODE
(4) Select the 2.White balance base from the SERVICE MODE.
HOW TO EXIT THE SERVICE MODE
Press the [MENU] key to exit the SERVICE MODE
POWER SUPPLY CIRCUIT 
CLICK ON THE IMAGES TO ZOOM IN


SELF CHECK FUNCTIONS
OUTLINE
This model has a self check function given below. When an abnormality has been detected, the power is turned off and the POWER LED flashes to inform of the failure. An abnormality is detected by the signal input state of the control line connected to the microcomputer.
Detection item
Detection content
Diagnosis signal (line)
Detection timing
Low bias line
short protection
Confirm the operation of the low bias (3.3V/5V/
12V/24V) protection circuit.
3.3V: Q7004 [SIGNAL PWB]
5V: Q7003 [SIGNAL PWB]
12V: Q7001 [SIGNAL PWB]
24V: IC7019 [SIGNAL PWB]
LB_PRO
At 10 seconds after the power is turned on, the
self-check function starts. If NG is detected during
3000ms, the power is turned off automatically.

METHOD OF DISPLAY WHEN A RASTER IS NOT OUTPUT
In the state where a raster is not output by breakdown of the set, an error is displayed by blink of the POWER LED.
Low bias line short protection ------------------LED turning on and off at 2 seconds intervals.

If an error is detected, the power is turned off. Shortly after the power is turned off, the POWER LED will be blinked. Power cannot be turned on until the power cord takes out and inserts, after the power is turned off.
Posted By: FRANK at 02:08
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