Cant find specs for cheertek LCD driver

Go To Last Post
9 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

HI,

I recently opened up my old portable dvd player. the Li-Po battery went missing several years ago, so by now its dead, and we no longer had use for it.

To my surprise, the top screen panel, housed not only the lcd, but a driver which drives the LCD from composite video. Ive been looking for something like this for a very long time. currently the best i could find was something like a super low quality tiny TFT driven by a chip of similar function with a built in regulator and rca jacks, it cost $70.

Now, i have a big problem, two actually, the first is that, i have no idea what kind of voltages and currents this thing requires/handles, the second, is i have a strong tendancy to break electronics when i experiment with them knowing nothing about them.

so far, ive found that the module seems to be regulators, current limiters, drivers, all operating off one IC, which is a CT675C-LF. So far i havent even been able to get so much as proof that cheertek even exists, let alone a datasheet for this, or any other "thing" cheertek manufactures.

I was wondering if anyone know where i might locate the cheertek datasheets? or more specifically what mine uses, or, would anyone happen to know how i would otherwise work out the voltages and neccesary currents the lcd uses. the pins are configured ignd vgh vee vcc vdd vin vss s-c gnd cvbs/y agnd sda scl, which ones do i need, minimum to operate the driver? i want to play composit video on the lcd. also, what would normal operating conditions be exactly? such as, which, are positive and negative, and what kind of power is typical for them?
My lcd is 7" and uses a small cfl inverter.

please help, any help would be greatly appreciated

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Cheertek is probably a chinese ic design house that you will be lucky to find anything on. It would probably help if you knew chinese. You'll just need to power it up and make some measurements.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

so, where exactly do i start at? do i just gradually step the voltage from 3V and hope for the best? Underpowering it wont cause any issues at all will it?
It probably would have helped to have been able to run the dvd player and to test the voltages on each pin.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Where do you start? I think you're up shit creek! I have no direct experience with these things apart from having a pile of dead dvd players in my workshop. I'll see if i can figure something out in the next few nights.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I pulled apart two fairly recent portable dvd players with integral lcd. Seems the main chip (mediatek) drives the lcd directly via a 24way flat cable. There's a few dc/dc converters on the board so I expect a variety of voltages. No luck today, sorry.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I located a schematic showing a CT675C, 128 pin LQFP. Whether or not it's the LF suffix it doesn't say.

Not a data sheet but might help.

ftp://relay.alkotel.ru/service/D...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I did a google search and then Yahoo! and if you want the datasheet you have to buy 5 pieces, and then the MFR. will send you the datasheet.

That part is pretty well known, so I am surprised that no one had posted anything for it.

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

mikericetga wrote:
I located a schematic showing a CT675C, 128 pin LQFP. Whether or not it's the LF suffix it doesn't say.

Not a data sheet but might help.

ftp://relay.alkotel.ru/service/D...

thanks a bunch for that one, i dont really understand it, at all, but im sure i can find someone to interpret it for me.

im pretty sure all the model variations use roughly the same inputs. what i did find out is that my one, the lf, only works for lcd screens up to 10 inches, so all the model variations really just differ to be compatible with bigger lcd's.

however, on my board, out of the following pins, ignd vgh vee vcc vdd vin vss s-c gnd cvbs/y agnd sda scl, which are the ones i actually NEED? things like hue, saturation, contrast and ect arent needed, i just wanna power it on, and hence, if i am to experiment, im better off putting 3v into the input, rather than the brightness pin. i have fried too many things to trust myself with experimentation so , which pins are the positive power inputs and ground? or which pins, should be those?

jgmdesign , could you please provide links to this place that alledgedly has datasheets?
If i do get this thing to work i will definitely use it for future projects, im gonna learn this things guts out, so depending on cost i probably will buy some, or otherwise sell them off on ebay. so, could you please share your findings?

thanks all

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

is there no way to apply external power to the player itself and see if things are still alaive that way.
Then you can check with a scope what is happening.

for sure you need the supplies vdd, gnd. You need to check if the negative supply and the contrast supply are to be made by you or are made by the chip itself and are there just for reference. You can try to do a run back on the board to see if the lines go to regulators or just resistors.
If you know that you probably need sda, scl ( twi or spi(then there must be a chip select somewhere too)???) to configure the chip, so you will need a datasheet in the end to see what commands are available. Or have a sniffer that tells you what is happening.

edit:
Is there no el cheapo chinees ebay site that sells fake batteries for that thing so you can revive it and then first start poking with a scope to see what happens where?
I know we have a dutch companny that seems to be selling batteries for almost everything including fakes...