Have had this TV since June 2019, worked fine till today. Daughter was watching it and made a noise and went dark. I unplugged, left off then powered back on, no change. You can see the image with flashlight test, but has high pitched noise/whine and no backlight whatsoever......I also tried a factory reset with the reset button on the back. Any ideas where I should start troubleshooting? Im pretty good with soldering iron and multimeter, but I dont have any documentation on this TV so I dont know where to start.
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Re: TCL 75R615 has sound, no backlight
I would start at power board. Sounds like shorted component causing the led driver to make noise. Need some pictures of boards.I assume no responsibility for any stupid suggestions I might post. -
Re: TCL 75R615 has sound, no backlight
So, I got some help yesterday to take the TV off the wall and got the back off to check out the boards....I did find a capacitor that was blown out,looks to be C312 a ceramic disc capacitor, very small and challenging to read, but was able to with a magnifying glass.....it seems to be a 220pf 1kv, I ordered some new ones from digi-key. A couple of questions, I dont notice with this type of capacitor that there is any polarity that needs to be observed? I have replaced numerous electrolytic caps and they have obvious polarity markings on the circuit board as well as the cap itself. Please see the attached pictures of the part number of the panel as well as some pictures of the internal boards, please offer up any help if you can....Thanks.Attached FilesComment
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Re: TCL 75R615 has sound, no backlight
No polarity on those. Does it measure as shorted?I assume no responsibility for any stupid suggestions I might post.Comment
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Re: TCL 75R615 has sound, no backlight
I just checked the component via continuity test and it is shorted.Comment
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Re: TCL 75R615 has sound, no backlight
This is a high-voltage ceramic capacitor, they have no polarity, you can safely install it as you like.Comment
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Re: TCL 75R615 has sound, no backlight
You can probably remove it and see if everything powers up. Just read my disclaimer first.I assume no responsibility for any stupid suggestions I might post.Comment
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Re: TCL 75R615 has sound, no backlight
I think I'll wait till I receive the new component, before I power it back up....Comment
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Re: TCL 75R615 has sound, no backlight
I would remove the disc cap and check it out of circuit, I would also check the mosfet QW301 & QW302. I usually replace these 1kv caps with a 2kvComment
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Re: TCL 75R615 has sound, no backlight
When you say take the disc cap out of circuit, I'm assuming you mean the one that blew up and not another one near it or a different one? I did desolder it took it out of circuit and it tested shorted out ....I'll also check the two MOSFETs like you suggested......crap, I already bought the 1kv version instead of the 2kv like you said.....Comment
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Re: TCL 75R615 has sound, no backlight
I'm surprised you had video.I assume no responsibility for any stupid suggestions I might post.Comment
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Re: TCL 75R615 has sound, no backlight
The 1k will be fine if that is what you ordered.Comment
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Re: TCL 75R615 has sound, no backlight
Thanks again for the info. I get on here mostly to learn. Do you know what happened to budm? Looks to be about a year since he posted.I assume no responsibility for any stupid suggestions I might post.Comment
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Re: TCL 75R615 has sound, no backlight
QW301 & QW302, as far as testing them....can they be tested in circuit, or do they need to be removed to be tested, I just want to make sure I do it the correct way.....im sure I can google a testing procedure, but I want to do it the quickest, most correct way....
Please let me know and thanks again for everyones help with this, it is much appreciated.....Comment
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Re: TCL 75R615 has sound, no backlight
You can check without soldering them, their legs should not be short-circuited with each other, this capacitor is parallel to the diodes.Comment
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Re: TCL 75R615 has sound, no backlight
Ok, I'll test them later on this afternoon and post results on the mosfets....Comment
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Re: TCL 75R615 has sound, no backlight
I tested both QW301 & QW302 in circuit and they are testing open across all legs.....I'm assuming per previous post that this means they are most likely good....Comment
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Re: TCL 75R615 has sound, no backlight
Well they shouldn't test open. Probably not testing them right, but they almost always test shorted if bad.I assume no responsibility for any stupid suggestions I might post.Comment
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Re: TCL 75R615 has sound, no backlight
Ok, does anyone have a good source for how I should be testing these particular mosfets? Ive viewed a few videos on youtube, but just looking for suggestions.....
Thanks!Comment
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this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even... -
Hello everyone,
Ive got a UE60KU6079 on the workbench that is giving me some headaches trying to troubleshoot.
The previous owner stated that there had been white dots on the screen which from the description sounded like some lenses fell of the backlight LEDs.
He had opened the TV from the back, trying to get to the backlight, supposedly gave up, reassebled everything and gave the TV to me.
I expected the worst like ripped COF cables or a cracked panel but could not find anything like that yet.
Anyway I still fully expect that there has been something seriously damaged... -
TCL 75S421
PSU BOARD: 40-L402H8-PWD1CG
it shows not even a flash of backlight when powering up.
but the tv appeas to turn on and i can hear the sound of the menus moving and clicking. i can power down the tv with the button.
testing the backlights with my tester all 4 strings lit up and showed similar voltage drops. around 110 or so.
unplug mb and leave only psu plugged into backlights (PSU + BL SELF TEST MODE?) does not light the backlights.
i do see 24v but 0v on PSON and BLON (i didnt write this down tho so cant be sure)
with mb connected, PSON... -
Hello all! New to TV repair and trying to bring a TCL 75R615 back from the dead. I've tried to do my basic research/reading but am at a loss so thought I'd see if anyone had some suggestions.
The TV powers up and I can see the backlight on. I can hear sounds by navigating the remote.
I tried disconnecting each side of the LVDS cables one at a time, powering off for a while between, and it didn't change anything. So my first guess was the TCON board so I order a replacement and swap that in. Didn't change anything.
Next I thought I'd try swapping the... -
Hello.
I have an issue with HP 8470p - rather strange one.
I have a noise and sound distortions on both internal speakers and external speakers, when I plug such into the 3.5mm audio jack.
Seems like the noise is present especially when I play audio, where there are parts/sections where the volume of the actual recorded sound is low.
Interestingly, when I play the windows sound test, everything seems to be almost okay. The sound/distortions are similar to when you have interference from some other piece of equipment nearby or when you have an audio receiver with bad amplifier...12-31-2021, 10:25 AM
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