The problem: When remote controller is press, the TV seems to wake from standby light goes off; but there is no backlight, image and sound. The relay did click on.
I have removed the power board to check. Using 2 x 10K resistor from 3.5V to PWR_ON AND DRV_ON, all the voltages is correct.
The main board has a red LED and is lited, but the optic link does not light up.
The Power board after sometime will start to blink x 5 interval.... I would assume this is to indicate DRV_On not working.
Any expert here came across the same problem? I...
wushumike
Member
Last Activity: 05-10-2023, 12:11 AM
Joined: 06-24-2016
Location: singapore
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LG 65UB930T - Standby Light can trigger but TV dead
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Re: LG55UH615T pulsating Redstanby LED
Thanks Davi.p
You have nailed the problem.
Ironically, I repaired the original board instead of the one I purchased. I use the purchased (faulty board) and did some comparison.
So the problem of my original board is as follows:
1. IC 801 faulty ...... internal circuit issue and it also affects the reading of R806 (10K)
2. R822 4R7 value increased
3. While trying to unsolder the MOSFET Q802 5N40, one of the lead drop off , so I cant say if this MOSFET is good or... -
Re: LG55UH615T pulsating Redstanby LED
IC 801 = MAP3516
I try searching for Datasheet... not available.
I can only assume this is a 2CH LED Backlight controller chip.Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
I'll try Dav.P method to check the MOSFET and IC (I did purchase this IC 801 from Ebay but yet to arrive)
Nothing can get worse, any suggestion to nail the problem are welcome....Only last resort yo get another PS board....Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
I did that already...Confirm not LED strip....Last edited by wushumike; 02-24-2023, 06:02 PM.Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Already did that...confirm is not LED strip because the light switch side.......Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Picture showing the backlight section...is the set LED +/- on the right side that is problematic...Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Any sugguestion for repair? ... The right and left sets of LED are common LED+ but the return path goes separate ways for this power board....Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Many time getting old boards from CN reseller is a gamble because they dont usually test the boards if is OK .....This is the second time I encountering.....Previous repair I bought a samsung ps....so badly repaired and not working and they refuse to refund...bought again from another supplier and it works....Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
I bought a second hand power board from CN.... all working except the right backlight LED is very dimly lited
When replace, the right side backlight LED is dimmer....and the Left side is OK...
Initially I thought the new LED strips are giving problem... so I swap the pair of LED ie left connection to right connection.... Now the one that was dim lights up without problem..... So to say the backlight LED is not the problem
I'm not sure if this second hand power board is faulty or not.... but then...Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
After replacing both LED backlight. The power board seems to be damage too because the backlight still not lighted up.
Searched and bought an old power board from China seller...fixed to the TV, one side light up normal but another side the LED is dim. Attached photo.
P.S. Initially I thought was the new backlight LED giving problem, I swap the pair of LED of left to right side and now the right side brighten up and normal.
Anyone can advice if it is this replacement board is also faulty?... The...Last edited by wushumike; 02-24-2023, 08:53 AM.Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Kudos.... You are absolutely right. As I do not wish to spend too much time and money on this TV, I remove the LCD panel to check if it is really the LED problem.
Upon dismantling, the right side LED strip was burnt at the very end... I have remove and physically check both strip to see what is the extend of the damage. The left strip all LEDs are OK. For the right side, apart from the burnt end, in between there are a few shorted LEDs.
I would assume the power board sense that the voltage or current...Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
As I have did a preliminary check on the power board backlight related component, all seems to be OK... and also when I remove the backlight connector, the stand-by light is back to normal.... it can turn on and also can see faint image with torchlight test.
Anyway I have decided not to waste money and time on this TV, I have decided to go thru the tedious way and remove the panel to physically check the backlight led. ( Just to satisfy my curiosity and doubt)
Voila.... the right side LED was burnt...Last edited by wushumike; 02-12-2023, 11:10 PM.Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
As per instruction, without connecting motherboard and pull up PWR_ON, PDIM1, PDIM2 and with backlight connected, NOT lighted up....
I remove the backlight connector to measure voltage of LED+ with reference to chassis ground. Pin 7 (LED+) = 30VDC ; Pin 1 (LED+) = 300Vdc.
There are two pairs wires both LED+/LED- ....... the copper trace LED+ is common, but the LED- is not.
I do not have a LED backlight tested so no able to check the LED strips......Leave a comment:
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Re: LG55UH615T pulsating Redstanby LED
Update on further testing.
I have disconnect the backlight connection and try power on. Now the standby LED is normal..... it only blink when I connect back the backlight connector. I would assume that the motherboard is working because without the backlight connector, I can see faint image with torchlight shining on screen.... although no sound, but could be the tv setup... not sure because difficult to run setup without light....
Any expert to comment ?Leave a comment:
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LG55UH615T pulsating Redstanby LED
LG model 55UH615T when plug into AC, the Red standby light pulsating slowly. Not sure if it is logic board or power supply.
Troubleshoot Power board as follows.
1. Connect to AC source
2. Measuring P201 connector, there are 7.8V from the 5 pins.... assuming this is the standby voltage.
3. Connect the 7.8V via a 1K resistor to PWR_ON pin, the output change to 13.2V ....so I would assume the power is correct.
4.There is no 186Vdc for the backlight.... Not sure if this should turn on with step 3.
5. Voltage across the two caps is 284Vdc..... -
40-T8222P-MAD2XG n 40-T222P-MAE2XG
Hi,
My current philip motherboard part number is 40-T8222P-[B]MAD2XG[/B]
Can any expert advice what is the different between these two motherboard
40-T8222P-MAD2XG
40-T8222P-[B]MAE2XG[/B]
Can the I replace my current mother board with the MAE2XG model.
Thanks in advance/Hi,
My current philip motherboard part number is 40-T8222P-[B]MAD2XG[/B]
Can any expert advice what is the different between these two motherboard
40-T8222P-MAD2XG
40-T8222P-[B]MAE2XG[/B]
Can the -
Re: Philip 42PFL5609/98 - Intermittent
Nope..I got no resource for IR reflow.
I will try Diah method of burn-in today to see if any good.
Will update status.
Leave a comment:
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Re: Philip 42PFL5609/98 - Intermittent
Yap agree...Just googling around....
I have removed the aluminium shield to take a look at the processor area...no dry joint or bloated cap...I have also use the same heat blowing method.but problem still remain.
As the fault is intermittent...I really have no ideal what is wrong...
Frm the schematics, there is this standby mode processor...could this fail?..but then there are firmware burn into the processor...so no way to replace .
Leave a comment:
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Re: Philip 42PFL5609/98 - Intermittent
Hmmmm....
I attach my tv mb photo and taobao snapshot...
Eeee... initially I thought was the year...but 93 is just too old...Leave a comment:
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