Sharp LC-70C8570U

[lonewolf55]

Re: Sharp LC-70C8570U

this is not for this TV but it is close enough, using it as a guide.

it's this Bugger All 41 Pin LVDS connector making it a PIA, I don't have an adapter for it

[lonewolf55]

Re: Sharp LC-70C8570U

Not that it really makes any difference, But you folks seem to like Pictures of Nekid TV backsides

[budwich]

Re: Sharp LC-70C8570U

have your traced all the voltages that are needed at the main board (as labeled)? Possibly one that is used to switch the pwm wave is not there. Further, trace the pwm wave / pin to the main board and see what device it passes by / thru and see if it is ok.

still further, although you indicate that you don't have a flash code, have you tried the "force on sequence" (power plug plus volume volume up ?) and see if perhaps that will get the set "limping".

[lonewolf55]

Re: Sharp LC-70C8570U

PWM1 is a straight shot thru the Main Board From the LVDS connector straight to the PD connector.

there is continuity from Pin 5 of the LVDS thru pin 17 on the Main board PD connector all the way to pin 17 on the PD connector of the Power Board, PWM1 is for sure generated by the T-CON and no components on the Main Board control it.

in my last post you can see the black wire hanging down connected to a Meter lead, that is the wire that goes to Pin 17 of the PSU PD connector (PWM1), you can see a small jumper wire that I used from Pin 15 to pin 17 on the PSU this forces the Backlight on right now just for troubleshooting.

All Supply Voltages are present on the Main Board, the T-CON Board, and the PSU per the SM, and the markings on the PSU Board.

on the PD connector of the Power Supply the voltages that I question are:

Pin 17 = 0v this is PWM1
Pin 19 = 0.82v this is Dimmer
Pin 21 = 0.13v this is OFL
Pin 23 = 0v this is PWM2 <<== this signal is not listed on the SM Block Diagram

And Yes I have tried Force on and Factory Reset as best as I can without being able to see the Menu on the screen LOL

I'm digging around on the PNL_EN N PNL_EN signal on Pin 3 of the LV connector on the T-CON Board right now, it toggles when power up/down then stays at 0v probably normal as it shows it is an inverted Signal, I'll have to pull out the Logic Probe or the Scope to see what it is really doing.

[lonewolf55]

Re: Sharp LC-70C8570U

OK I have the Correct SM now.
This is the Correct Block Diagram and the SM for any that want it.
The other Block Diagram that I posted earlier is still Valid as a Guide.

[budwich]

Re: Sharp LC-70C8570U

ok... thanks the extra info... good stuff. You mentioned that you were able to "toggle on the backlights" via a jumper. My question is: have/can you tried same "toggle" toggle with everything connected to see if the set presents a display... if you say you are only missing that signal, then you should see something... maybe.

Further, the corner cable may not be there, depending on the design but I would expect a 70 in set to have side edge boards which need to be connected to the bottom boards.

There might be some frame components / covers (either plastic or metal) on the backside that need to be removed to expose them. The hint would be that you need to see the entire bottom edge boards.

one other thing... you should follow the voltages from the tcon to the bottom edge boards.... some form of vcom or others should be there.

[lonewolf55]

Re: Sharp LC-70C8570U

These are my PD voltage readings on the PSU Board.

Thanx for the Reply, I'll look at the voltages on the Panel, But yes I will need to do a bunch of disassembly to get at it and right this moment I don't have a free Bed to lay it on until the Wife allows it LMAO

I still think the T-CON alone should give me PWM1 without the Ribbons connected, 4 Service Shops in the area have verified this, and several PEW-TUBE videos seem to claim this too. So I think I need to figure that out before digging into the Panel, I messaged Sharp several days ago but I am still on IGNORE

I went ahead and ordered another T-CON, as I have no way to connect my LVDS tester to the T-CON that is in it now.

I have an old T-CON that was changed out years back and it seems to have the same issue.... neither here nor there I think the Old T-CON was Bad anyway.

OH, and when I get the new T-CON I will not connect the Ribbons when I put power to it the first time to see if the Backlight issue is solved.

[budwich]

Re: Sharp LC-70C8570U

no problem... just suggestions as I have only limited experience via a 2-5 flash code "save".
Your thought about the disconnected tcon - panel cables is "valid"... however, I seem to recall some threads on a sony type set that "unloading" a tcon (ie. no panel) resulted in the system not powering up but my memory is "old"... :-) My note would be that the system has "montoring" in its "guts" for "overdraws" (especially around the 12v supply). There is no reason to believe that "similar protection" can't exist on the other end. Further, Sony uses some of the sharp panel so the "guts" may have similar semantics depending on age ... how far the design was in ancestory. Just as vizio also uses sharp panels but doesn't have any protection outside of blowing fets on the tcon so perhaps tv vintage / design "breaks" the "all disconnected tcon cabls" adage.

Further, I am not sure that your "pwm" is "DC" based... hence not sure of the validity of a dc measurement in terms of investigation although a DC "test input" may indeed be valid as "full on".

[lonewolf55]

Re: Sharp LC-70C8570U

Right on the PWM to me it means Pulse Width Modulation .. I use PWM a lot with Stepper Drivers and in CNC etc etc while a steady state won't show you still can see the needle of the meter move when you have a signal and the Voltage will "Appear" to vary ....... now on a Digital Meter maybe you will see Voltage depending on the Duty Cycle of the PWM Signal, while it's not the best way to look at a PWM signal it is a down and dirty way to see if it is there or not Thanx for all the help, just talking thru the issue helps and having other input makes me think in other directions ALL GOOD

[lonewolf55]

Re: Sharp LC-70C8570U

ok the signals that I question in Post #64 come from VCOM Calibrator on the T-CON, so it seems that I have found the area of my Problem.

Here is basic pinout of the 41 Pin LVDS connector called LW how Fitting LoneWolf

[budwich]

Re: Sharp LC-70C8570U

VCOM (or something like it) should be in the 15-18 volts area (based on forum readings)... it is used among other things, to drive the panel and passes towards the edge boards.... but now you are in the "deep end" and "I can't swim"... :-) Problems occur with some SMD components (capacitors mostly) on the bottom edge boards shorting out result is "over draws" / shut downs. People have found them and sometimes are able to replace with careful work as the boards are NOT removable because of tabs. Note: those components are usually in parallel with "multiple units" along with some "tracking" in the panel... so finding that faulty one is sometimes very difficult to isolate.... unless you get lucky visually (blown, marked).
Not saying that's your problem, just an area you might look towards. Of course, your replacement tcon might be all you need when it comes.

[lonewolf55]

Re: Sharp LC-70C8570U

the thing is I know you may be very Correct as in the Beginning I suspect it is a Panel Issue, it's possible that it can Blow Tcons as fast as you can replace them. My guess is that I have a Power Source on the T-CON that is bad right now, but this could just be the Tip of the Iceberg.

I do see buck/boost circuits on the T-CON Board, but right now I'm still trying to Identify Test Points to figure out WTF to test.

I have Identified the Vcom power Transistors on my T-CON and several other areas, I sure wish I had a Block Diagram at least of the board.


This is the Best I have so far......

[budwich]

Re: Sharp LC-70C8570U

Good work... keep "swimming" :-) "glub, glub, glub".

[lonewolf55]

Re: Sharp LC-70C8570U

I can get the Screen to be Black or white on either side by the usual removing one side of the Ribbon Cables from the T-CON but this is not really proving too much as there is still no Video present (and no Snow) but this could be due to loss of a voltage on the T-CON or it could be still an issue on the main Board, I'm still not sure what should be present on the OFL and DIMMER <== I'm not worried about that just yet as I do know that PWM1 is not Present and this is a sure sign of something going on with the T-CON.

The Bottom Line is I need to fire up the old TEK TDS420 and start looking at the LW connector, at least I know what those signals should be now.

I'm not an HDTV Tech, but I have spent well over 50 years doing Discrete component repair on all sorts of industrial equipment and computer systems, so I will be on this like a Dog with a Bone until I find the exact cause of the Failure (I did run a TV/VCR repair shop on the side for about 10 years back in the late 70's early 80's) but now days it seems most just Shotgun repairs, and that can be pretty expensive

BTW I do have a good SMD Re-work Bench with a nice positioner and Microscope, so these boards are not an extreme Challenge to repair after you figure out what is bad, I can do Re-Balling too, hope it don't come to that

[budwich]

Re: Sharp LC-70C8570U

Ah.... but the "test" causing "white" or "black" is a "standard result" of "some tcon to panel disconnected cables... that is different than what you reported with "all disconnected".... as "white", if there is no "dark spots" indicates working backlighting.

It is important to do the tcon to panel disconnect with one cable at a time and note the results exactly. this will tell you more about the panel. further, ensure you are feeding a signal in and / or at least hitting the menu to get some display. You can go from there.

[lonewolf55]

Re: Sharp LC-70C8570U

Ah.... but the "test" causing "white" or "black" is a "standard result" of "some tcon to panel disconnected cables... that is different than what you reported with "all disconnected".... as "white", if there is no "dark spots" indicates working backlighting.

It is important to do the tcon to panel disconnect with one cable at a time and note the results exactly. this will tell you more about the panel. further, ensure you are feeding a signal in and / or at least hitting the menu to get some display. You can go from there.

No is not different than I reported, you could not tell this Until I forced the back lights on, with no Backlights you cannot tell any difference when cables are connected or Disconnected.

Also with no Back lights, it makes no difference with what cables you disconnect, you cannot tell the difference.

[lonewolf55]

Re: Sharp LC-70C8570U

this set has 6 LED strips 3 on top 3 on Bottom, the Backlight inverters on the PSU do not turn on until you have PWM1.

the real issue is that for some reason the T-CON is not producing PWM1 Sorry if I sounded confusing.

[lonewolf55]

Re: Sharp LC-70C8570U

the outside connectors are 80 Pin and go to the LR388H5 IC I believe these are what you call the FFC cables and the other 2 Cables are 64 pin and these are Control Cables <<== my best Guess.

anyway no matter if T-con cables are connected or what order of disconnect, there is no Picture information to be seen not even OSD Menu, even when forcing the backlight on.
The screen will just be Black or White.

[lonewolf55]

Re: Sharp LC-70C8570U

OK I found the Issue VGH 35v is failed no voltage on the T-CON

I have full Schematic of the F961FM01 board now

OK attached is the Area of the Failure.. I've yet to nail down exact components yet, but good chance this could be caused by Bad Panel.

Maybe it will help someone else.

[lonewolf55]

Re: Sharp LC-70C8570U

and here is what Sucks PWM1 is the GPO0 pin on the LR388H5 IC so in fact it is not being powered as that pin has 0 voltage


it's taking awhile but I'm getting a good understanding of how this board really works and VGH is gate drive to that LR388H5 also.

the attachment is just a tidbit on the LR388H5 specs, I couldn't find a full Datasheet to inspect.