Panasonic led tv, 3 red blinks error, TH-L32X30M

[litec systems]

Hi
First of all, English isn't my primary language, so it might not be perfect..
Admins- I've do search before posting but can't find a thread about LED tv 3 blinks..
Anyway, I've picked that tv from the trash.. ( I'm always like to learn and troubleshooting electronics. And mostly, TV'S)
The thing is that when i plug in the TV, the green light blinks fast ( as should) then it is start to blink 3 times Red...
From the service manual-, named TC-L32E3, gotten from " manualslib" (NOTE, it's not the exact tv model but it looks very similar - the TV that this manual belongs to is probably with one more HDMI &\ just made for different end countries.. But the PSU, LOOKS THE SAME) and from things that I've already test& troubleshoot ( which some of them are);
1. Check voltages, got these readings ;
Standby- 5.7V is solid
Sub on(equal to PS ON\ enable on competitors?) = ~2.5v , starts with plug in the TV, and goes when it enters to protection mode and start blinking
C7502= 11.67V
C7501= 24-25.2V
***BL SOS- = 3.281V while protection mode- is that pointing on a problem with the LED driver? Or its part of the protection to turn them off and flag the LED as a SOS too?***the driver do gets 24v( so i guess no blown fuse there)
* LEDS strips being tested by LED tester and found good( ~52v each)
SO, according to the tests above & service manual IM ASSUMING ( & needs your opinion and confirmation) (-
1. The PSU is working ( maybe the PWM \ communication IC is broken?)
2 the LCD panel ( or the LVDS) are shorted\ bad?( I've try to locate a fuse on the lcd, but didn't find one)
3. This TV, designed pretty different from the usual ones, if I've got the design correctly, there are only a 5.5v standby and a 16V outputs from the PSU, and then, the IC5000 at the logic board acts as a multi step down & protection IC?
Anyway, how can i locate the real culprit ( logic board, LVDS cable, lcd panel, some IC on the logic board?
Thanks and merry Christmas!

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

https://www.badcaps.net/forum/attach...7&d=1577321957
The LED driver takes in 24VDC and then the boost converter circuits on the LED driver boosted up the Voltage close to 100V.
The the meter between the two legs the filter cap, 160V 47uf, on the LED driver board then turn on the TV while keeping an eye on the meter to see how high the Voltage jumps up to then wait 10 seconds to see how low it goes down to.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

Hi
Thanks for your quick reply
Is the BL SOS might related to an faulty LED DRIVER or I'll have to fucos on the service manual & what I've already found in order to get the TV out of protection mode?
Ive forgot to mention that, the manual says that 3 blinks is SOS(Tuner_SOS) SUB3.3V/panel_15V
So I'm assuming that panel, refers the LCD.. But about the Tuner, is that the aerial antenna? If so, I've found that on continuity mode on multimeter, it's beeping like a short, is that pointing to the problem? What do you suggest in order to troubleshoot and hopefully, repair the TV?I'm assuming that the RF tuner shouldn't reads as a short to ground right?, but on the other way, it sounds little rare that the tuner will have a fault( unless they used very low quality one) and let me think that maybe the step down (IC5000) is the culprit?

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

Please do the test as I suggested in my post 2.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

HI
Thanks again for your quick reply
sorry ive didn't got you on your previous reply ..youve wrote "The the meter between" and it tooks me a while to assume that thats an autocomplete and you meant to tell me what to test [before that ive thught that you just described how it works and not what to test..]
1.THE OUTPUT CAP has only 24v on the first`seconds[ till it goes into protection - then its starts to drop from 24v all the way to ZERO volts[this takes about 3.5minutes in order to fully discharge the cap] - all of this is while the red LED keeps blinking
2. because the ANtenna input have short to GND ive try to find the 3v (?) regulator and with the service manual ive reached to IC8700- which gets 16v from the PSU[ as should] and named "3.3v sub"- and on that output(pin 3?) im getting 3.975v[ till the protection starts]
and the regulator near it [ same model"IC8701"] -have A reading of ,6.195v[named SUB5V on the manual]
3. IC5000 readings( by pin #):
#1=15 v
#2=8.9V
#3=0.9- its triyng to start right before the protection starts
#12[panel sos]3V TILL protection starts[ shouldnt it work the opposite? when theres a fault the SOS reads 3v?
#15 3.2V TILL protection starts
#32= 3.3v-SD card -doesnt drop on protection
#31=sub5V-doesnt drop on protection
#30=***STB5v**-shows only 1.146 all the time - thats weird
#29=stb3.3- -shows only 1.416 all the time - thats weird
#28=**STB1.2 **3.273 on startup-3.266 on protection.... is that pointing on a bad regulator??
#27=STBRST- 3.357v TILL protection starts
#20=BUFF_EN-5.068V TILL protection starts
#18=BUFF_3.3_OUT- 5.068V TILL protection starts-** is that points on a short with pin20?- pin 18 named as a 3.3V OUT- but theres a 5V...
#17=BUFF_5v IN- no output

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

"1.THE OUTPUT CAP has only 24v on the first`seconds[ till it goes into protection - then its starts to drop from 24v all the way to ZERO volts[this takes about 3.5 minutes in order to fully discharge the cap] - all of this is while the red LED keeps blinking"
That means the boost converter circuit did not even try to come on, it can be that the LED driver board is not getting the BL-ON signal from the main board to turn it on.
Right now we cannot be sure if the service manual is perfectly matched to your board or not so the Voltages readings may not be correct.
Please upload good clear pictures of the whole backside of the TV showing all the boards so we can see how they are connected together.
I am hoping that the connector of the power supply board that goes to the main board will have the pin label to tell us what each pin is for and get to see what the Voltages for power supply pins and the control signal pins are.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

hi
ill upload pics within the next ~10 minutes
till then the BL-ON is just 0.06v.. so it is didnt even try to turn on-- BUT maybe thats the design? so the BL turn on AFTER few tests?[ lets say panel etc?[ ive never had any panasonic tv]BUT the BL-SOS gets 3v when the protection starts

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

So there are pin labels for the power supply connectors?
We need to know what the Voltages are when TV is off and when power switch is activated.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

"I am hoping that the connector of the power supply board that goes to the main board will have the pin label"
That's the first thing that I've looked for.. Unfortunately, there isn't.. There are only test points...
Anyway, sorry for the delay, here are few pictures.. If you need more please let me know..
Thanks alot!

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

https://www.badcaps.net/forum/attach...2&d=1577395979
I am not sure if the LED driver board connector LD4 pinout matched the service manual CN2 pinout or not.

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

The main board should send out the BL-ON to try to turn on the backlights circuits first, if there is problem then the BL-SOS signal will be generated to tell the main board that there is issue with the backlights.
SOS signal will be generated AFTER the circuit is trying to work and fail.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

ive add it just for the description below the picture of the bl on\sos
anyway heres the pdf im working with
https://www.manualslib.com/manual/83...-Tc-L32e3.html

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

I found these: https://elektrotanya.com/showresult?...oria=&kat2=all
They may be closer to your chassis.
I did not down load the 30c or 30d to see if they are closed to what you have or not.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

The main board should send out the BL-ON to try to turn on the backlights circuits first, if there is problem then the BL-SOS signal will be generated to tell the main board that there is issue with the backlights.
SOS signal will be generated AFTER the circuit is trying to work and fail.

If so, then what's your suggestions to keep looking for the culprit?
Is the fact that the Aerial input has a short to Ground \ the slightly overvoltage difference \ any other voltage readings that I've posted here has something related to the culprit?
Here's are the IC5000 pinout ( that's what I've posted the readings on the previous reply
Ant the LDO'S chips pictures too( IC8700 8701) ...Maybe the slightly different at the voltage causing protection? ( not sure if the 5v should be 5.0\ 5.8v like I've saw on that PDF)

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

I found these: https://elektrotanya.com/showresult?...oria=&kat2=all
They may be closer to your chassis.
I did not down load the 30c or 30d to see if they are closed to what you have or not.

ok ill DL both and try to compare them..
if ill still need help- which part of them ill have to attach here? the psu\ MB pinouts?
thanks!

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

IC8700 (v5857?): https://www.badcaps.net/forum/attach...3&d=1577399926
LDO: https://www.badcaps.net/forum/attach...5&d=1577399926
I do see the relationship of the IC8700 and the spec of the LDO (AN???). Do you have the spec sheet of the IC8700?
Right now we need to find out what you have on the power supply connector that goes to the main board.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

Here's the schematic of the 8700
https://cdn.badcaps-static.com/pdfs/...e954603180.pdf
Its a changeable LDO. (it's 4 am here so I've didn't read yetthe schematic you offered)
But ive remember that with the PDF that I've used so far, it shows that the sub3.3v line, goes to one of them (8700/8701-ive marked them...
And the other one should output 5\ 5.8v( and it reads 6.xx v)

[budm]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

Here's the schematic of the 8700
https://cdn.badcaps-static.com/pdfs/...e954603180.pdf
Its a changeable LDO. (it's 4 am here so I've didn't read yetthe schematic you offered)
But ive remember that with the PDF that I've used so far, it shows that the sub3.3v line, goes to one of them (8700/8701-ive marked them...
And the other one should output 5\ 5.8v( and it reads 6.xx v)

That IC is step-down SWITCHING IC, not LDO, the output is set by the feedback resistor network.

[litec systems]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

What's the difference between a regular and a switching step down? Similar to regular one but with turn on\ off ( maybe protection too?) signals?

[ngth82]

Re: Panasonic led tv, 3 red blinks error, TH-L32X30M

What's the difference between a regular and a switching step down? Similar to regular one but with turn on\ off ( maybe protection too?) signals?

Renesas has a good intro to the differences between a linear regulator (LDO) and a switching supply.

With LDO's, you step down in voltage by generating heat. Output efficiency depends on the Vin-Vout difference.
With Switching supplies, you step down in voltage with a PWM controlled signal. Output efficiency gets as high as 95%+ with minimal switching losses.

Most supplies have over-current production as well as output short protection.

https://www.renesas.com/us/en/produc...egulators.html