Sanyo DP32647 Backlight flickering

[budm]

Re: Sanyo DP32647 Backlight flickering

Thats when the set is powered on, the 2.4v reading is when it is turned off.

That cannot be right then since for the backlights to come on the BL_ON will have to be >2VDC, and <1V for backlights OFF.
Right now it is reversed of what it should be for this inverter board.
You need to put everything back to original to see what kind of signals of each TV should be to operate.
I will also remove the cable to the T-CON board on this swapped setup incase the Voltage supplied to the T-CON board is 12VDC instead of 5VDC.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

I looked at page 15. Should I lift one of the pins out to open it, say maybe PIN 14?

[budm]

Re: Sanyo DP32647 Backlight flickering

Right now it does not matter until you get the correct BL_ON signal polarity, we also do not know what the mainboard is sending the correct signals to the inverter board on pin14 since they are not the same signal name. one is E-PWM, the other board is MODE SEL.
You have one main board from another TV to drive the different inverter board from another TV.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

Let me double check what I just said I am sorry if that is mistaken I have had a long day today ha.

Alright so with the unit off the reading is

ON/OFF:1.75V, however it jumps around 1.64v,1.69v, 1.8v, ect.

With the unit turned on the reading is

ON/OFF: .48v, .49v, .50v, .51v, .48v ect moving around in that range.


Keep in mind, the original panel and the original inverter board do the same flickering with the backlight.

[budm]

Re: Sanyo DP32647 Backlight flickering

Let me double check what I just said I am sorry if that is mistaken I have had a long day today ha.

Alright so with the unit off the reading is

ON/OFF:1.75V, however it jumps around 1.64,1.69 1.8, ect.

With the unit turned on the reading is

ON/OFF: .48, .49, .50, .51, .48 ect moving around in that range.

See page 10 for what BL_ON has to be for the backlights to be ON.
Your signal is REVERSED!

[coreyand]

Re: Sanyo DP32647 Backlight flickering

AHHH, Pg10 was blank with only the header on the pdf I got. How could I go about testing this. Could I jump 5v from somewhere else on the board to test this, and then the obvious question of reversing the polarity on the mainboard. I think the answer is drawing to the point that it probably is just not going to work because of the way the main board is setup.

Still If I jump 5v from my main board to the BL_On do you think I would get a solid back light or blow it up?

[budm]

Re: Sanyo DP32647 Backlight flickering

You can but you MUST disconnect the BL_ON wire going back to the main board so it will not back feed the Voltage from force on and damage switched transistor on the main board. You should use 100~500 Resistor to limit the current feeding the BL_ON, you will use 5V Standby Voltage and it must be applied AFTER THE TV is powered ON.
The PWM lines may need to be disconnected also.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

Okay, let me get out my gator clips and I will get right back with you

[coreyand]

Re: Sanyo DP32647 Backlight flickering

Heres something interesting. Should the backlight be flickering even when pin #12 has been removed from the mainboard? The flickering and back light stops when I lift pin number #13. With 5v applied to the ON/OFF with a 200 resistor the back light stops flickering but is very dim. I am actually not sure they are on anymore.

[budm]

Re: Sanyo DP32647 Backlight flickering

Pin 13 is analog dimmimg and 14 are for dimming, 13 for internal and 14 for external, so only one can be connected according to the spec sheet.
The lamps are dim right now is due to the Dimming command from the main board that may be set to low brightness right now, and since this pin 14 is looking for PWM signal but we do not know what kind of signal is being sent from this main board since the correct inverter has pin 14 as MODE SELECT not E-PWM as this inverter board you are testing is looking for PWM signal.

Correction, you cannot have pin 13 and 14 OPEN at the SAME time.
If pin 13 Analog dimming is used (Variable 0~3.3V, 3.3V = MAX BRIGHTNESS, 0V = MIN BRIGHTNESS), THEN PIN 14 must be OPEN.
If pin 14 PWM dimming (10% ~90% pulse width @around 250~500 Hz) is used, then pin 13 MUST BE OPEN.
So what you have to is to remove pin 14, and then apply 3.3V MAX to pin 13 or use variable power supply to let you adjust the output the Voltage between 0V to 3.3V to vary the lamps brightness.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

Alright well applied 5v to the BLON which is pin #12, nothing changed except the flashing was not as bright. Tryed removing pin#13 and the entire backlight stops, pin #14 seems to do nothing as far as the backlight goes.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

I have noticed that when pin 13 and 14 are open at the same time the set does nothing. Only when I have pin14 closed on the main board the backlight flickers. Pin 12 and 13 can be off the board and doing nothing and the back light flickers still.

Update: If I ground pin 13, the flickering stops and the backlight remains on at a constant level.

[budm]

Re: Sanyo DP32647 Backlight flickering

Correction, you cannot have pin 13 and 14 OPEN at the SAME time per spec sheet, see post 30 for update.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

I have noticed that when pin 13 and 14 are open at the same time the set does nothing. Only when I have pin14 closed on the main board the backlight flickers. Pin 12 and 13 can be off the board and doing nothing and the back light flickers still.

Update: If I ground pin 13, the flickering stops and the backlight remains on at a constant level.

So the flickering quit once I grounded pin 13. No image on the display. Im thinking the TCON, So I put the TCON in that came with the panel and I get an image but its all off. Im sure because of the pinout not being the same and the voltage rating differing. In the process of putting the other TCON back I bent some pins on the ribbon cable. I am going the take the ones off the bad panel and put them on this one.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

BUDM, Grounding pin 13 got the back light to stop flickering. I put in the TCON that came with this panel originally instead of the old one because I was not getting a picture.

Discovering that I had mangled up some of the connections on the left side ribbon cable is what caused a bad picture the first time I looked at it. Discovering that the ribbon cables on the old panel are attached to the panel board I had to carefully straighten them out and carefully reinsert it into the TCON board that came with the the panel.

The only thing I fear like you said about swapping out tcon's and the pinout being different. But at the moment it looks like its doing just fine.

Is pin #13 supposed to be grounded like that?

Update: I put pin #13 back where it belonged(I think, I may have gotten 13 and 14 mixed up in the process). The picture brightened up nice and looks clear. Better than I would have expected. Really though budm Thanks for all your help. I will be on here again soon. I have a 42" Poloroid tv I think the TCON is bad in, or its the panel. Can I ask you about it?

[budm]

Re: Sanyo DP32647 Backlight flickering

Well that is good news, so what do you end up using what boards, panel in which chassis?
You should start a new thread for the Polaroid and please make sure to upload good clear pictures of the board, etc.

[coreyand]

Re: Sanyo DP32647 Backlight flickering

The end result is I used a CHI MEI panel out of a 32" RCA L32WD22 for this Sanyo DP32647. I am using the TCON board with the CHI MEI not the original that came with the Sanyo.

Budm, I am not sure what the entire flickering on the backlight was all about. I know the specs said the voltage was inverted by our understanding on the BL_ON, but after I grounded Pin #13 the back light quit flickering. Then after messing with the TCON boards back and forth (Tv was powered down pin #13 was still grounded.) I put the TCON that went with this CHI MEI originally, and bestowed upon me was a clear picture although dim. With the tv still powered on at this time I ungrounded the pin #13 and put it back in its original place on the mainboard. This brightened the picture up to where I would say is the normal brightness for this tv.

Also the inverter boards stayed on their original panel.

Call it a mad science project with all the things that should have gone wrong in swapping this panel out, but somehow came out right and is working beautifully...so far. I have already reassembled TV and will be putting some test time on the TV to see how it fairs out. I think its going to be fine honestly.

I think perhaps the original problem with the backlight flickering like it was could have possibly came from using the old TCON board on this different panel. I am not sure how it would effect it like that but this flickering problem seems to have gone away after I switched to the TCON board that came on that panel.

Thank you for all your help Budm! I really appreciate it. Now on to my next project.

[budm]

Re: Sanyo DP32647 Backlight flickering

Well you are very lucky that you do not have to hack the T-CON connection like what I have to do here:
https://www.badcaps.net/forum/showth...LN32A300J1DXZA

[Shane711]

Re: Sanyo DP32647 Backlight flickering

Well I have this TV as well, I actually have several TVs I need to fix. So I have this Sanyo DP32647 and there is no backlight at all. So I tested all the voltages and they all seem to be good. Voltages are steady. I hear the TV click on and when I shut it off I hear it click off. The power indicator light on the front does not light up at all. I checked the inverter board, testing all the fuses and did an ohm test on the transformers. I disconnected the T-Con board to see if that would make a difference but nothing. So I am guessing it is a main board problem.

[budm]

Re: Sanyo DP32647 Backlight flickering

@shane, you need to check the Voltages and signals at the inverter board to see if it is receiving the Voltage (24VDC is typical) to run on and if it is getting the BL_ON, DIM control signals from the main board or not.