Re: Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested goo
Update: The op-amp (U14) was also bad. After replacing this op-amp and the optoisolator, the TV is working again.
events.b
Member
Last Activity: 11-26-2023, 04:12 PM
Joined: 10-25-2010
Location: Florida
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Re: Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested goo
Update: One of the optoisolators for the backlight current feedback I found to be open circuit. I replaced the optoisolator but still no change. I suspect the op-amp that drives the optoisolator is also bad.Leave a comment:
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Re: Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested goo
Hello, after the LED shutdown, the voltages are as follows:
The 400V caps near the LED backlight connector are at 0.4V
The signal labeled "BK" is 4.5V
The signal labeled "ADJ" is 4.1VLeave a comment:
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Re: Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested goo
Yes, I did take the panel apart because I too initially suspected faulty LEDs. The tester was showing about 79 volts I think, on each array. The TV has two separate LED arrays, one on each side. I illuminated each array separately with the tester and they both showed the same voltage. This is what caused me to step back and second guess myself, because I would expect one array to have a different operating voltage if it had bad LEDs. Each and every LED did in fact come on, although not at full...Leave a comment:
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Re: Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested goo
So, you think the tester is giving me a false negative? That's disappointing to hear that it is a flawed test. I will try your suggestion and record a video to see if that gives any clues, thanks for the tip.Leave a comment:
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Sceptre X505BV - Logo appears for 1 sec then backlight shuts off, LEDs tested good
Hello, this TV currently has me stumped. As the title states, when I power on the unit, the backlight comes on for 1 second then shuts off. The TV is still on, and I can see the video if I shine a flashlight on the screen.
Using the LED backlight tester I was able to confirm all LEDs are illuminating and seem to be working correctly when independently powered by this tester, so that leads me to believe there is something wrong with the power supply board.
Perhaps the great minds here can help me figure it out, as I don't see any thing obviously wrong with it. The... -
Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
Circled in red, it goes directly to the VCC pin (pin 5) of IC6...Leave a comment:
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Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
Found an opened resistor that supplies VCC power to the IC6. Replaced it and +5Vsb exists now!
Unfortunately still not standby LED and no sign of life, I suspect main board is faulty as well.Leave a comment:
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Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
I also found this link, selling a "repair kit" for LK4180 power supply:
[url]http://www.ohmsupplies.co.uk/epages/62027733.sf/en_AU/?ObjectPath=/Shops/62027733/Products/KIT279[/url]
I emailed support and asked for IC6 part number, they told me it's this:
[url]http://www.ohmsupplies.co.uk/epages/62027733.sf/en_AU/?ObjectID=5696877[/url]
SG6859
datasheet: [url]https://cdn.badcaps-static.com/pdfs/229fdf21b6a9a1e563f6e717ac0ffcfd.pdf[/url]
...Leave a comment:
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Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
Hi,
After some googling I came across this:
[url]https://elektrotanya.com/content/gaba-glv3296-lcd-be-keresnek-lk4180-000b-tap-panelt[/url]
It's Polish but it seems like they identified it as LD7535
datasheet for LD7535 is here:
What do you think? Do you agree? ThanksRe: Apex / Jensen JE3708 bad PSU, no...p-panelt[/url]Leave a comment:
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Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
Oops, sorry, that one also has 160VDC.Leave a comment:
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Re: Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
IC1 is unfortunately covered in epoxy and I cannot read it.
IC2 is ST Microelectronics L6599D
The big main filter cap carries 160VDC on it.Leave a comment:
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Apex / Jensen JE3708 bad PSU, no 5VSB, can't find schematic
Hi,
I'm working on a Apex JE3708 with no 5V standby. Main cap is showing 160V as expected. The part number on the PSU is LK4180-001G, but I can't find schematics anywhere for it. I have identified what I believe is the smps controller for the 5VSB circuit, it's a small SOT-23 with markings "J135" or "J13S" on it, shown in the attached image. Can anybody help me identify what IC it is or maybe point me in the direction to find the diagram? Thanks guys.... -
Re: LG 42LD450 struck by lightning, replaced main board, now every other column is re
Replaced the T-CON, TV is fixed! Another one back in service.Leave a comment:
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Re: LG 42LD450 struck by lightning, replaced main board, now every other column is re
Hey dskall, I checked and reseated the cables to the t-con, they look good, it didn't make a difference. Could this be a failure of the as15f chip?Leave a comment:
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LG 42LD450 struck by lightning, replaced main board, now every other column is red.
I got a LG 42LD450-UA with the worst case of lightning damage I've ever seen. The main board was absolutely toast. The lightning came in through the composite inputs and took out those circuits, the main board was a total loss. I replaced the main board with a compatible one, but now every other column is red. It seems too consistent to me to be a panel fault, at first I thought it was incorrect firmware, but after checking the INSTART settings and force flashing the latest correct firmware using the wonderful resources at [url]http://openlgtv.org.ru/[/url], the problem still persists. At this... -
Re: Sanyo DP42848 42" LCD TV: sound, but no picture
So, it turns out there were actually 2 failed lamps. 5th from the top and 5th from the bottom. I ordered 2 used lamps from an eBay seller for $20 shipped for both, as new lamps were too costly for me at around $25 each. The replacement lamps were from a different TV but were 99% correct size. They were just a tiny bit thinner, and I noticed they were ever so slightly loose in the sockets. So I used a soldering iron to solder them into place to avoid any issues with loose connection. To my surprise, the metal coating on the...Last edited by events.b; 07-17-2016, 03:12 PM.Leave a comment:
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Re: Sanyo DP42848 42" LCD TV: sound, but no picture
Well I finally got around to taking the panel apart. I found the source of the problem
As expected, there is a burned out CCFL. It may not be easy to tell in the attached photo, but it is the 5th one up from the bottom. I will order one from CCFL warehouse and see if I can get this thing back together without damaging the panel. Wish me luck!...
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Re: Sanyo DP42848 42" LCD TV: sound, but no picture
Hi,
I have the same model TV and same issue. I have not yet opened up the panel but I am getting ready to do it once I find a folding table to set everything up on. Here is the datasheet for the inverter controller: [url]https://cdn.badcaps-static.com/pdfs/4969701ffac2b7389db14e2e0aa1635e.pdf[/url]
I will let you know if I find anything interesting inside the panel
Re: Sanyo DP42848 42" LCD TV: sound,... same issue. I
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Re: Seiki SE322FS w/sound/no video
Can anyone provide a clear picture of the back of the power supply, I have a blown power supply with unrecognizable resistors: R53, R58, R65, R66, R67, R68
Service manual would help too
ThanksLeave a comment:
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