Sharp LC-60LE633U 2-5 flash

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

So I guess one of these Q7200/ Q7223 is the guy to check on. I'll have to look at the circuitry after work, since I cant find PSU schematic online.
I don't have a scope, so if you have any pointers I could sure use them.
Thanks for that explanation!

[budm]

Re: Sharp LC-60LE633U 2-5 flash

So let me get this correctly, the backlights do come on and stay on?

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

So let me get this correctly, the backlights do come on and stay on?

yes they do

and let me make this correction:
+ve to GND is 206
-ve to GND is 132

I bet that's why you asked that question .
I posted them backwards. Sorry about that

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

If you look at the board layout, all the L1+~4+ are tied together and fed by the switched power MOSFET Q7223, the filter caps are C7200, 7201.
The PWM controlled sink power MOSFET Q7201, 7206, 7207, 7208 are for each LED strings (4 strings), and the 4 PWM controller ICs 7201, 7204, 7205, 7206 are for driving the PWM ICS. I do not see boost converter being used on this board.

That's what I see as well.
I also checked DIMMER (PD-19) to GND and saw 2.5V (backlight was set to +16 in menu).

Validated that PD-19 will go from 2.5V down to 1.089V at the lowest back-light setting, so at least the CPU board is sending that signal correctly to the PSU.
That change has no effect on the led -ve

PWM IC are DDA11A PYUS. Looking for datasheets for pin out.

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

Further testing:

I have confirmed that the back light control from CPU makes it all the way to the PWM IC's at pin 7.
That signal varies from 1 to 2.5V going from lowest to highest back-light settings

The mosfets Q7201, 7206, 7207, 7208 always have 132V on the middle pin. (Drain)
So led +ve is 208, the strip drops ~74Vdc and ~132V is seen on the led -ve.
Since led -ve is tied to middle pins on Q7201, 7206, 7207, 7208 that's why I see 132V there.

I'm assuming based on budm's statement that Q7201, 7206, 7207, 7208 should actually turn on and run that 132V to ground in some amount (according to the PWM output).

Since all 4 led power are identical, I assumed I have to look for the common link.:

1. Pin 2 on all PWM IC go thru some resistors and end up at Q7120 pin 4 @2.5V.
2. Pin 3 is 12V for all PWM IC
3. Pin 4 on all PWM IC go thru 1k resistor and are tied back to the power mosfets Source measuring 0V
4. Pin 5 on all PWM IC also thru 22ohm resistor and are tied to the power mosfet Gate. All pins measure 0V
3. Pin 6 is GND
4. Pin 7 on all PWM IC varies with back light adjust


PWM IC Pin 4 goes back to that OP AMP LM 258A thru a myriad of resistors and transistors.

Since G-S needs to be +ve, I believe that I need to focus on the PWM IC PIN4, and see why I have 0V there.
( I didn't notice anything that could drive the Gate above 0V, so hence my thought that S needs to go -ve, and because it runs back to the OP-AMP, I think that's where I need to focus and brush up on its operation)

[budm]

Re: Sharp LC-60LE633U 2-5 flash

Total Vf of each LED string will stay same, the current through the LEDs will vary with backlights level setting. I.E, if you force 100mA through a silicon diode, the Vf will basically stay the same as when you force 200mA through it.
You have to look PWM signals with scope.
See example circuit how the LED strings are driven.

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

budm,

I do not have access to a scope, but I got a raspberry pi around here, which I think can read PWM with some code.
I just need to protect it's input, do you have any idea what the max amplitude from one of those driver IC is?
I couldn't find a data sheet on them yet, but I know their supply voltage is 12V.

[budm]

Re: Sharp LC-60LE633U 2-5 flash

The Gate drive amplitude should be just above the Gate threshold Voltage which can be around 3~5V range.
You have one end of the current sensing resistor on the S pin for the MOSFET, the other end is connected to GND, the feedback signal developed across the sensing resistor is ued for feedback to keep constant current through the LED string.

[budm]

Re: Sharp LC-60LE633U 2-5 flash

'The backlights are lit- I pulled the panel, proved that & I can see the backlight is on thru the holes in the back.' The thing is you can see the backlights but the screen is dark. What do see if you disconnect the ribbon cables between the LCD panel and the T-CON board?
And if any of the LED string is bad the protection circuit will kick in. Unless the LEDs are light up at very very min brightness but I would not expect it to be so low that you can barely see anything on the screen.

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

'The backlights are lit- I pulled the panel, proved that & I can see the backlight is on thru the holes in the back.' The thing is you can see the backlights but the screen is dark. What do see if you disconnect the ribbon cables between the LCD panel and the T-CON board?
And if any of the LED string is bad the protection circuit will kick in. Unless the LEDs are light up at very very min brightness but I would not expect it to be so low that you can barely see anything on the screen.

I still get the grey/black split screen if I disconnect one tcon cable. The grey side depends on which tcon cable is disconnected.
With both out- it looks black to me
They are really dim IMO. I don't know if my photos show that, but I am sure all leds lit up.

[budm]

Re: Sharp LC-60LE633U 2-5 flash

What Voltage do you have on the Dimmer control pin 19 of the PD connector?

[budwich]

Re: Sharp LC-60LE633U 2-5 flash

Since you are questioning what the original owner might have done to the set, I am wondering whether it is possible to "push" in a reload of the software and see if things change any.

From my limited experience with the 70 in sharp, there was a few things that I noticed. First during initial power up, only a small portion of the perimeter lighting would come on for a brief period, then go out, then come up again with full lighting all around. The screen would be some form of display lighting depending on what was selected at the time but not full brightness, more dark grey. If nothing was selected quickly there after, the set would go into standby fairly quickly there after basically looking dark. In my case, repeated selection of the menu would bring the "dark grey" back since the menu was limited in terms of display with information only around the top and one side.

I am thinking that you have some sort of "dimming" set either as "standby" or as a setting... maybe.
I guess looking from the back (with back off), I could see the differences in the perimeter lighting from start up, to "full display" (of something), to "standby" which was "dark" / "screen saver" mode... maybe.

Related to the first part, do you know if your main control card was replaced?

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

What Voltage do you have on the Dimmer control pin 19 of the PD connector?

Bud that's currently 2.5V...I maxed out back light.
My usable range is 1.0 to 2.5


I think I got the rasp pi setup, but now I realize I need a known good PWM signal to verify I setup correctly...oh the mess I get myself info

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

Since you are questioning what the original owner might have done to the set, I am wondering whether it is possible to "push" in a reload of the software and see if things change any.

From my limited experience with the 70 in sharp, there was a few things that I noticed. First during initial power up, only a small portion of the perimeter lighting would come on for a brief period, then go out, then come up again with full lighting all around. The screen would be some form of display lighting depending on what was selected at the time but not full brightness, more dark grey. If nothing was selected quickly there after, the set would go into standby fairly quickly there after basically looking dark. In my case, repeated selection of the menu would bring the "dark grey" back since the menu was limited in terms of display with information only around the top and one side.

I am thinking that you have some sort of "dimming" set either as "standby" or as a setting... maybe.
I guess looking from the back (with back off), I could see the differences in the perimeter lighting from start up, to "full display" (of something), to "standby" which was "dark" / "screen saver" mode... maybe.

Related to the first part, do you know if your main control card was replaced?

The main board looks original. I could do a sw update, it does connect to wifi and stay connected. SW could be current, so might just not do anything.
I think I even did a reset from the regular menu.
Looked in service menu, didn't see anything obvious there.

[budwich]

Re: Sharp LC-60LE633U 2-5 flash

It was just a thought. Anyways, I think you want to force an update as opposed "asking". I think you do that thru a usb stick.

Reset from the regular menu won't necessarily do much other than user stuff. If the previous owner was in the SM, he might have done something that only a "reload" of firmware might change... back to "base".

[budm]

Re: Sharp LC-60LE633U 2-5 flash

PWM, at 50% duty cycle of 5V, the AVG DC will be 2.5VDC. So that should give pretty good backlights level. So, try fimware to see what happens.

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

back in post 49:
https://www.badcaps.net/forum/showpo...0&postcount=49

budm asked about tcon cables. I went back to refresh my memory with that.
After disconnecting/reconnecting tcon cables, I lost the right 1/4 of the screen. (photo attached). So that killed my ability to use the menu.
I do not believe the panel has any issue.

I thought I screwed up something on my ribbons or tcon itself, so I installed the tcon I bought ( I remembered I parked it after I solved the 12V panel error).

With that tcon, I noted some bright flashes, then the back-lights dropping back to 'barely lit'. I played with the power on of several times and then I was able to get full back lights, it lit up like a christmas tree. Photos attached.

However this tcon provides absolutely NO picture. It provides a permanent BLUE screen on the left side, and a permanent grey screen on the right with the ribbons connected. I get a FULL bright white split screen if I disconnect the tcon.

Its not 100% reliable to get it lit up- I have to play with the power button.


My question at this time is, how could I get backlight with one tcon but not with the other? I thought that when tcon ribbon is disconnected, back lights should always come up if they are good.

[budm]

Re: Sharp LC-60LE633U 2-5 flash

On this model I am not sure if the T-CON is also used for dynamic contrast control or not to give that faked 50,000:1 Contrast ratio by varying the backlights based on the scene of the Video.

[calimark]

Re: Sharp LC-60LE633U 2-5 flash

On this model I am not sure if the T-CON is also used for dynamic contrast control or not to give that faked 50,000:1 Contrast ratio by varying the backlights based on the scene of the Video.

Well I did measure the PD-19 with that board and its the same 2.5V just as the dark board.
I did however find some voltages on those led driver mosfets.
I think 6V or so where I had 0 before so something changed.
No matter what I do, I cant get backlights like this with my original tcon.
So there is definitely some info coming back from the tcon to cpu to psu to make all that happen.

Probably gonna give this a rest for a few days and get another tcon after I hear back from the seller.

[budwich]

Re: Sharp LC-60LE633U 2-5 flash

"However this tcon provides absolutely NO picture. It provides a permanent BLUE screen on the left side, and a permanent grey screen on the right with the ribbons connected. I get a FULL bright white split screen if I disconnect the tcon. <<<<-----

What do you mean by this. You disconnect the tcon from the panel (all cables 2?) or the lvds cable from the tcon to the control board.

what happens with just one cable disconnected? Try each side?