Daewoo CM915 No Picture Problem

[Shahriar]

Hi

I have a PARS TV with a chasis of CM915, I think It is Daewoo

Here the Schematic
http://www.4shared.com/file/87846048/11b79109/CM9151.html
(Upload it in ur site if there isn't any)

The Problem with that is there is No picture and sound while The High voltage and all the DC Voltages are correct; The Remote Does Not wotk; No OSD or anything else
I increased the Screen On HV Transformer but nothing on the screen;

DC Voltages on CRT Socket is also Correct;

The amazing thing is when You Push The Main Power switch it Starts Automatically but when You put a New and Raw 24LC16 EEPROM IC, The first time You push the Main Power Switch It goes to stand by and wait for the Power-On Switch which works good with Remote Too;
When U Power It up in this way, again No Picture, When You repeat this It doesn't Go to Stand-By again and start Automatically. I think the Proccessor write Something in EEPROM;

The Last thing, The first Time I Looked for the Problem I found Q802 on Power Section (A940 PNP Transisotor) with Base-Collector Open It Converts 66V to 14V; I replaced it, The 14V is OK, But the Problem Also exist

I Have Not the Program for The EEPROM IC to write a new one;

The LED Remain Red; While It should Goes Green when Th MCU Start
THE RGB Pins on MCU (62,63,64) are 0V;
The Power-Fail Pin of MCU (Pin 3) is Low;

Is it possible that MCU Detect a Failure some where and This Happen?

I cheked all DC Voltage by Multimeter On VDC;

ThanX in Advance
Shahriar
_________________
Sometimes it's o.k. to let the smoke out!

[jts1957]

Does EEPROM have 5 volts? Are filaments lit?

[Shahriar]

Thank U veru much

The +5V On EEPROM Is Okay
The Filament also Lit (+130V OK)

Is it possible anything wrong with ABL? The Voltage on Pin 22 of Video Processor (I501 Page 5) is going Up More than 3V; Is it natural?

ThanX
Shahriar
_________________
Sometimes it's o.k. to let the smoke out!

[jts1957]

Looks like (Q802) 14volts stand by supplies 8 volt stand by and 5 volts to EEPROM.
If ABL were involved, where's the audio and OSD and remote, etc.?
With no picture and no sound (and no raster [even a dim blank screen] when the screen/G2 is turned up) along with the lack of "control," sounds like system control is the correct area to be looking.
Here in the USA, most EEPROMS we get from TV manufacturers, come preprogrammed with "generic" settings that can then be tweeked.
Have you scoped Clock and Data lines on EEPROM (also SCL and SDA on Micro/T-chip, etc.)? Should have activity on them, when, for example, Channel up is pressed, then quiet back down.

[vtech]

While it definitely sounds like a system control issue, you may want to keep in mind that since a I2C protocol is utilized in this chassis, any device not responding can easily lock up the processor. Short of just scoping the lines, there is no reliable way to analyze the data w/out expensive equipment.
I am not familiar with the specific chassis but for example, have seen it on Panasonic products where a faulty tuner stops syscon operation all together.

In looking at the schematic, Pins 42 and 45 (SCL & SDA) of the main processor are used for communication with various components within the circuit as a Master/Slave configuration. Technically any device in the loop including the processor itself can cause problem. In my experience though, microprocessor failures are very rare unless dealing with power surge issues.
You can see I2C communication lines between the main processor, EEprom and various IC's (including the tuner).

Here's an article describing I2C (if interested)
http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm