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 !

Monday 11 March 2019

JVC LT-37X688 SERVICE MODE AND POWER SUPPLY CIRCUIT

JVC LT-37X688 SERVICE MODE AND POWER SUPPLY CIRCUIT


JVC LT-37X688 

SERVICE MODE AND POWER SUPPLY CIRCUIT 


SPECIFIC SERVICE INSTRUCTIONS
Be sure to carry out the following operation at the end of the procedure.
(1) Set to "0 minutes" using the [SLEEP] key.
(2) While "0 minutes" is displayed, press the [VIDEO] key and [DISPLAY] key simultaneously, then enter the SERVICE MODE.
(3) Press the [1] key in the SERVICE MODE SCREEN.
(4) Press the [2] key in the TV-MICRO SERVICE MODE screen
(5) The SELF CHECK MODE screen is displayed.
(6) Turn off the power by pressing the [POWER] key on the remote control unit.
FEATURES
Built in ATSC (Advanced Television Systems Committee)
TUNER
This TV can receive both Digital broadcasting (ATSC) and Analog broadcasting.
D.I.S.T. (Digital Image Scaling Technology)
This system uses line interpolation to double the number of scanning lines and achieve high resolution, flicker-free picture. Color Management
This function ensures dull colors are compensated to produce natural hues.
Picture Management
This function makes it easier to see the dark areas when a picture has many dark areas, and makes it easier to see the bright areas when a picture has many bright areas. Smart Picture This function detects the APL (Average Picture Level) and adjusts the contrast suitable for what you are watching.
DIGITAL VNR
This function cuts down the amount of noise in the original picture.
MPEG Noise Reduction
This function effects the block noise removal and mosquito NR simultaneously.
Sensor Effect
With Sensor Effect ON, a "leaf" icon will appear on your TV screen when Smart Sensor brightness adjustment occurs.
MEMORY IC REPLACEMENT
• This model uses the memory IC.
• This memory IC stores data for proper operation of the video and drive circuits.
• When replacing, be sure to use an IC containing this (initial value) data.
MEMORY IC REPLACEMENT PROCEDURE
1. Power off
Switch off the power and disconnect the power plug.
2. Replace the memory IC
Be sure to use a memory IC written with the initial setting data.
3. Power on
Connect the power cord to the wall outlet and switch on the power.
4. Receiving channel setting
Refer to the OPERATING INSTRUCTIONS (USER'S GUIDE) and set the receive channels (Channels Preset) as described.
5. User settings
Check the user setting items according to the "FACTORY
SETTING ITEM".
Where these do not agree, refer to the OPERATING INSTRUCTIONS (USER'S GUIDE) and set the items as described.
6. SERVICE MODE setting
Verify what to set in the SERVICE MODE, and set whatever is necessary.
ADJUSTMENT PREPARATION
(1) This TV is adjusted by using REMOTE CONTROL UNIT.
(2) The adjustment using the REMOTE CONTROL UNIT is made on the basis of the initial setting values. The setting values which adjust the screen to the optimum condition can be different from the initial setting values.
(3) Make sure that connection is correctly made AC to AC power source.
(4) Turn on the power of the TV and measuring instruments for warming up for at least 30 minutes before starting adjustments.
(5) If the receive or input signal is not specified, use the most appropriate signal for adjustment.
(6) Never touch the parts (such as variable resistors, transformers and condensers) not shown in the adjustment items of this service adjustment.
SERVICE MODE
BASIC OPERATION OF SERVICE MODE
Operate the SERVICE MODE with the REMOTE CONTROL UNIT.
HOW TO ENTER THE SERVICE MODE
(1) Set to "0 minutes" using the [SLEEP] key.
(2) While "0 minutes" is displayed, press the [VIDEO STATUS] key and [DISPLAY] key simultaneously.
(3) Enter the SERVICE MODE.
SERVICE MODE SELECT KEY LOCATION

HOW TO EXIT THE SERVICE MODE
Press the [MENU] key to exit the SERVICE MODE.
HOW TO STORE OF SETTING VALUE
When adjustment is completed, press the [MUTING] key to memorize the adjustment value.
NOTE: If not to do it, adjustment data is not memorized to the memory IC. And if exit the adjustment mode before memorize the data, the adjustment value which you change is canceled.
WHITE BALANCE (HIGHLIGHT)
(1) Receive a NTSC 75% all white signal.
(2) Set "VIDEO STATUS" to "STANDARD".
(3) Set "ASPECT" to "FULL".
(4) Select "COLOR TEMPERATURE" to "LOW".
(5) Select the 1.TV-Micro Service from the SERVICE MODE.
(6) Select the 1.Adjust.
(7) Adjust to keep one of <S002> (Red drive), <S003> (Green drive) or <S004> (Blue drive) unchanged, then lower the other two so that the all-white screen is equally white throughout.
NOTE: Set one or more of <S002>, <S003> and <S004> to "137".
(8) Check that white balance is properly tracked from low light to high light. If the white balance tracking is deviated, adjust to correct it.
(9) Press the [MUTING] key to memorize the set value.
SELF CHECK FEATURE
OUTLINE
This unit comes with the "Self check" feature, which checks the operational state of the circuit and displays/saves it during failure.Diagnosis is performed when power is turned on, and information input to the main microcomputer is monitored at all time. Diagnosis is displayed in 2 ways via screen display and LED flashes. Failure detection is based on input state of I2C bus and the various control lines connected to the main microcomputer.
HOW TO ENTER THE SELF CHECK MODE
Before entering the Self check Display mode, confirm that the setting of MODE SW of the REMOTE CONTROL UNIT is at the "TV" side. If the switches have not been properly set, you cannot enter the Self check Display mode.
<SELF CHECK MODE(TV-MICRO)>
(1) Set to "0 minutes" using the [SLEEP] key.
(2) Press the [VIDEO STATUS] key and [DISPLAY] key simultaneously, then enter the SERVICE MODE.
(3) Press the [1] key in the TV-MICRO SERVICE MODE.
(4) Press the [2] key in the SELF CHECK MODE(TV-MICRO).
<SELF CHECK MODE(DIGITAL)>
(1) Set to "0 minutes" using the [SLEEP] key.
(2) Press the [VIDEO STATUS] key and [DISPLAY] key simultaneously, then enter the service mode.
(3) Press the [3] key in the DIAGNOSTICS MODE.
(4) Press the [2] key in the SELF CHECK MODE(DIGITAL).
HOW TO EXIT THE SELF CHECK MODE
TO SAVE FAILURE HISTORY:
Turn off the power by unplugging the AC power cord plug when in the Self check display mode.
TO CLEAR (RESET) FAILURE HISTORY: Turn off the power by pressing the [POWER] key on the remote control unit when in the Self check display mode.
FAILURE HISTORY
Failure history can be counted up to 9 times for each item. When the number exceeds 9, display will remain as 9. Failure history will be stored in the memory unless it has been deleted.
NOTE: Only SYNC (with/without sync signals) will be neither counted nor stored.
POINTS TO NOTE WHEN USING THE SELF CHECK FEATURE
In addition to circuit failures (abnormal operation), the following cases may also be diagnosed as "Abnormal" and counted.
(1) Temporary defective transmissions across circuits due to pulse interruptions.
(2) Misalignment in the on/off timing of power for I2C bus (Vcc) when turning on/off the main power. Therefore, turn on the main power, and then wait for about 3 seconds before starting Self check. If recurrences are expected, ensure to clear (reset) the failure history and record the new diagnosis results.
POWER SUPPLY CIRCUIT 

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Posted By: FRANK at 02:37
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