Short Update - TV is working again. BGA Reflow of IC100 does the trick.
Long Story:[LIST][*]PWS,Edgelit,T-Con,Panel was working (checked before)[*]Previous missing voltages, all voltages are there, but my measurment method wasn't correct. I've partly measured directly on the IC output, which is before the LC part => I've measured the direct output frequency without smothing...🤦[*]All voltages on MB are correct, no further ideas beside BGA reflow[LIST][*]start with IC100[*]stipped down plastic parts from MB[*]removed the metal cover[*]Heatgun from below ~350°C[*]Heatgun on top...
Seb932
Member
Last Activity: 12-15-2023, 08:31 AM
Joined: 09-14-2023
Location: Saxony
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
buzz is already gone by replacing/bridging the burned choke, remvove the bridge buzz is coming back
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Thank you very much! I've an 8ch logic analyzer on hand, should be possible read JTAG as well. But need some time......Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Ok, will try. Any tutorial how to do this?...Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
yes, tested and working => 5V normal/USB are supplied by IC2304...Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Done already. eMMC Voltage is also correct =>3.3V. Still missing 1.0;1.2;1.5V......Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Need to give a correction, the burned choke is input for 1.2V voltage regulation, not output.
If I short the choke the buzzing noise is gone, but still this fancy PWM signal on output side...
No short measureable, also the 12V input is stable. Maybe its burned during some of the tests before. Because the buzzing noise i've recognized first during the test in [URL="https://www.badcaps.net/forum/showpost.php?p=1272409&postcount=18"]#18[/URL]Re: LG 49UB850V not...Last edited by Seb932; 09-19-2023, 08:22 AM.Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Tried to find L2302 to check eMMC V. During search I found L2322 is burned (resistance 440Ohms), which is output for 1.2V
Is it ok to bride the coil for testing purposes or better replace with some other SMD coil?...Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Damn, you are right
lowV start signal is available on all the regulators, as well as VDD 12V. I've checked this already. Means input is ok for all voltages, but output not for low voltage.
Looks like something grounds/overlay the output-signal...
Output IC3000 => Voltage Regulation IC => Result
POWER_ON/OFF1 => IC2304 5V => +5V_NORMAL OK
POWER_ON/OFF2_1 => IC2301 3.3V => +3.3V_NORMAL OK
POWER_ON/OFF2_2 => IC2302 2.5V...Last edited by Seb932; 09-19-2023, 07:16 AM.Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Have already tested the micro switch beside IC3000. It's the same like power on the TV. It triggers the MICOM reset => Power_On sequence starts again and stuck with the same result.
First question: You think about feeding additional external low voltage into the mainboard to bypass the voltage regulators?
Second question: what about the missing blue color in panel test mode? Could it be also a panel problem? How to test? If panel is dead I would not...Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Tried it, warmed up MB with a heatgun. Switched on, no change at all....Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Nothing because T-CON doesn't receive PANEL_VCC from MB. Thats why i've hooked up it directly to see if panel and T-CON are ok...
PANEL_VCC will be enabled by Q2303 with PANEL_CTL signal from IC3000, but signal is not coming (as well as DRV_ON from IC3000)...
I expect IC3000 is "waiting" for some other signals until releasing DRV_ON and PANEL_CTL....maybe related to the missing lower voltages on MB......Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Update on next round: First I've disconnected the T-Con from MB. Then hooked up 12V to T-CON F1 and also forced DRV_ON and POWER_ON.
BL lights up and Panels cycles White/Red/Green...nothing, i would expect blue. Only a break (for blue) then starting from the beginning.
To rule out BL finally i also stripped the TV down afterwards, edgelight is working pretty well. No dark LEDs, burned spots or anything like that. Put everything together again...
My conclusion =>...Last edited by Seb932; 09-19-2023, 04:36 AM.Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Maybe I've missunderstood. I've disconnected T-CON from the Mainboard. But reading carefully, you mean disconnect the panel from T-CON...
Tried again.... same result as before. Also in combination with disconnected speakers & wifi module......Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Have tried it. T-Con disconnected from PSU & Mainboard but nothing changed => Switching on, Standby LED blinks 3x. LD2300 on mainbord lights up and after ~30s LD701 on PWS board starts to blink 5x repetetive. No Backlight and also no red light in optic port. Additional a quietly buzzing noise in the region of IC100 occurs...
Put T-CON in again, buzzing sound is still there......Last edited by Seb932; 09-18-2023, 03:41 PM.Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
No it does not come, checket on PSU side and on IC3000 as well. Pin stays Low......Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Sorry, this was a typo. DVR_ON is correct. Pin2 on P201 PSU side. Its normally feeded from INV_CTL (IC3000). Will enable Backlight.
If i bride SBY 3.5V on PSU with POWER_ON Pin1 P201 => all voltages are anabled on PSU. If 3.5V are supplied to DVR_ON on PSU side the backlight lights up....Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
BL is fully functional. Tested by maual bridging SBY 3.5V to POWER_ON and DRV_ON on SMPS w/o connection to Mainboard....Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Have checked solderpoints, found some suspicious pins and resolderd it. Also have done some additional measurements.
Started with IC3000, responsible for "power on" sequence
If TV is switched on, the IC3000 enables the different voltage regulators. I've measured input signals (from IC3000) and output:
POWER_ON/OFF1 => IC2304 5V => +5V_NORMAL OK
POWER_ON/OFF2_1 => IC2301 3.3V => +3.3V_NORMAL OK
POWER_ON/OFF2_2 => IC2302 2.5V => +2.5V_Normal OK...Leave a comment:
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Re: LG 49UB850V not switching on / standby LED off / LD701 blinks 5x
Thanks for recommendation, will try to check and resolder suspicious joinst....Leave a comment:
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