Polaroid P50D300S No picture

[unxtres]

Black screen, there is sound and reaction for remote, backlight is also on
I`ve tried to change T-Con but same issue
Voltages on main and Psu are present there is also 12v on fuse on tcon
any ideas?

TV - Polaroid P50D300S
Screen - VES500UNDA-2D-N11
T-CON - T420HVN06.3
MAIN - 17MB97
PSU - Vestel 17IPS12

[dskall]

Re: Polaroid P50D300S No picture

You got anything on your data lines to t-con? If you unplug one ribbon cable at a time going to panel what do you get?

[unxtres]

Re: Polaroid P50D300S No picture

nothing, screen are still black, no, lines nothing, i have also checked caps on screen electronics for shorts but everything looks good, this tv is like ghost

[dick_barton]

Re: Polaroid P50D300S No picture

Have you checked that you have a supply voltage to the tcon?


Edit
Oops, I see you have already checked.

[unxtres]

Re: Polaroid P50D300S No picture

Have you checked that you have a supply voltage to the tcon?


Edit
Oops, I see you have already checked.

Yes and fuse are ok too, no shorts on ceramic caps

Big IC on t-con also getting to be warm when tv is on

Possibly firmware fault but i still i can change source (blindly) and there is sound in speakers.

[tom66]

Re: Polaroid P50D300S No picture

If you have a scope you can check LVDS lines for activity.

One "hack" is to try partially disconnecting LVDS cable and seeing if you get patterns on the screen. I wouldn't do this too much, but a brief check to see if the panel is working at all may be helpful.

My bet would be a bad panel.

If you have an RS232 to USB adapter and some wires there's a way to get a debug port on the SCART port of the TV, this will let you log in to the operating system of the TV to have a fiddle with some settings or test modes.

[unxtres]

Re: Polaroid P50D300S No picture

tom66 looks like bad panel, tried disconect ribbon conections and there is nothing on screen, looks like dead.

Im interested in this RS232 can you provide me some links or more info about it

[tom66]

Re: Polaroid P50D300S No picture

What's the motherboard model number? 17MBxx

[unxtres]

Re: Polaroid P50D300S No picture

17mb97

[tom66]

Re: Polaroid P50D300S No picture

Right... Can't find exact schematic but quick look shows same as other boards across the range.

You will need a USB to RS232 cable that accepts low voltage levels...MOST do, but some do not. If you do not have one then use this. NOTE most PC RS232 sockets will *not* work as they require the +/-10V logic levels that the TV will not use.

If you do not have one then use one of these:
http://www.ebay.co.uk/itm/2Pcs-Ardui...kAAOSw3lFZeGMf

I will assume you are using Windows.

First use software like PuTTY (https://www.chiark.greenend.org.uk/~...ty/latest.html) to use the serial port.

Enter your COM port number (you can find it in Device Manager on Windows) and baud rate 115200.

Tie the transmit and receive (TX and RX) of your cable/connector together. Then type. If characters are seen in PuTTY, your cable is working and set up correctly. (This is an echo test.) Note characters do not normally appear unless "echoed" by the receiver, therefore do not expect anything to appear when the cables are disconnected if you type.

Then you will want to connect the TX of your device to the RX of the TV, and RX to the TX of the TV. It is pin 12 that is the TV's transmit (TX) and pin 14 that is the TV's receive (RX). See this diagram for SCART pinout. (Note Vestel use the spare pins for the port.)

http://www.leadsdirect.co.uk/wp-cont.../scartdiag.gif

If all is well, when you turn on the TV, you will get a load of debug output. This may tell you if there is a problem in a specific area, for example unable to read a certain file which may be fixable via firmware update.

It should also prompt you to press a key to enter a terminal, which should let you enter the Linux operating system. If a password is requested, try "314159".

[unxtres]

Re: Polaroid P50D300S No picture

Thanks Tom that may be useful in future

Anyway i found that for this board 17mb97 RX are pin 10 and TX - 12
i need also to connect gnd to pin 14
i`ve got some strange output:

▒/y▒▒L▒{▒▒f▒▒5▒n▒▒▒▒cvr▒▒▒▒▒▒,▒w▒▒▒h▒▒a▒q▒a8▒=▒t▒▒▒cS▒y▒▒▒▒▒w▒▒▒w▒M▒u▒▒W▒▒$▒5▒+Z▒x▒S▒▒▒▒j▒4▒▒▒▒▒▒▒▒▒▒sf▒▒▒▒▒oq▒ާsw|P▒cŵ▒▒#c▒m▒▒?-

i have uploaded service manual for that board.

[tom66]

Re: Polaroid P50D300S No picture

You might need to experiment with different baud rates, 9600, 19200, 115200 and 230400 are commonly used; the series basically doubles between each value. You would need a scope to measure the bit period to know the exact baud rate.

[unxtres]

Re: Polaroid P50D300S No picture

i`ve tried different baud rates with highest value than 9600 ive got more data back but it is still unreadable :/

[dick_barton]

Re: Polaroid P50D300S No picture

If the service manual is the one for your mainboard then it looks like the connections will be:-

SCART Pin 10 = UART Rx (Received data)
SCART Pin 12 = UART Tx (Transmitted data)
SCART Pin 14 = Ground

From page 58

[unxtres]

Re: Polaroid P50D300S No picture

If the service manual is the one for your mainboard then it looks like the connections will be:-

SCART Pin 10 = UART Rx (Received data)
SCART Pin 12 = UART Tx (Transmitted data)
SCART Pin 14 = Ground

From page 58

Yes it is connected in that way

[dick_barton]

Re: Polaroid P50D300S No picture

Do as Tom suggested and disconnect the Tx and Rx wires from the SCART connector and short them together.
Run the Terminal program and set the baud rate and echo character.
Whatever you type should now reappear on the computer screen so if you typed "a" then "aa" should show on the screen.
Once you have that, you can then disconnect the wires and reconnect them to the SCART inputs. You may have to swap the two wires over.

[unxtres]

Re: Polaroid P50D300S No picture

dick_barton i receiving data from tv this is not issue with non working rs232.
as i mentioned several posts ago,

data that i receiving are not readable

please tell me again what that operation will change? When i short rx tx and send a char ?ill get response same char and....?

[dick_barton]

Re: Polaroid P50D300S No picture

I would say that it's stage one to know that what you transmit is what you are receiving so any corruption when connected to the scart socket must be a problem with:-
1. Baud Rate
2. Number of start bits
3. Number of Stop bits
4. Parity
5. Number of data bits 7 or 8 bits

All of which you can be varied in the communication program.

This may be useful
http://electronicshelponline.blogspo...-software.html

[tom66]

Re: Polaroid P50D300S No picture

The baud rate is the unknown, almost every system uses 8N1 Comms (8 bits, no parity, 1 stop, 1 start)

[tn245]

Re: Polaroid P50D300S No picture

You ever get anywhere with this? I've got a similar one with the 17mb97 board and no picture. The baud rate is 115200. I see it starting up on rs232 terminal but then it says UART disabled part way through start up and then nothing which is pretty useless as there's no way to see the menus to enable UART.