Originally posted by x_orange90_x
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Samsung UN50KU6300F constant reboot, bad backlights?
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Originally posted by vinceroger69 View Post
not sure as the tv maybe detecting a fault with backlights disconnected, there was a thread the otherday where the op was having no backlight isssue turned out it was a bad solder joint so check the psu for cracked joints etc
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Originally posted by vinceroger69 View Post
not sure as the tv maybe detecting a fault with backlights disconnected, there was a thread the otherday where the op was having no backlight isssue turned out it was a bad solder joint so check the psu for cracked joints etc
I did a quick voltage check on the plug to the main board and I have 5v standby. The other ones such as 13v and PS_ON fluctuate all over the place.Last edited by x_orange90_x; 02-17-2024, 12:51 PM.
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Did you check all the diodes on top of the board.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Originally posted by nomoresonys View PostDid you check all the diodes on top of the board.
https://www.badcaps.net/forum/troubl...78#post1751678
I seen in another post there's also a diode on the bottom that fails on some people:
https://www.badcaps.net/forum/troubl...-fix#post80203
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Yep, that's a bad one, maybe switch m both out for good measure.Last edited by nomoresonys; 02-18-2024, 05:59 AM.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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The video didn't work for me.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Originally posted by nomoresonys View PostThe video didn't work for me.
https://drive.google.com/file/d/1FOr...w?usp=drivesdk
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Are those voltages still fluctuating?SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Quick test, try heating C9371 with a hairdryer for a minute or two and retry it while it's still hot, no joy maybe test that resistor and test that transistor on the heatsink right there by it, see if any of the 3 pins are shorted to the other 2, or reads low ohms, should be able to test those in circuit. Try tracing where that bad diode goes, what components it leads to. And as always, make sure all your solder joints are good on bottom of board.Last edited by nomoresonys; 02-19-2024, 12:32 AM.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Originally posted by nomoresonys View PostQuick test, try heating C9371 with a hairdryer for a minute or two and retry it while it's still hot, no joy maybe test that resistor and test that transistor on the heatsink right there by it, see if any of the 3 pins are shorted to the other 2, or reads low ohms, should be able to test those in circuit. Try tracing where that bad diode goes, what components it leads to. And as always, make sure all your solder joints are good on bottom of board.
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I have a feeling it's that transistor. I will check that, the resistor, and that capacitor tonight. Id like to have kits of components on hand so I don't have to order so often. Like variety kits of transistors, diodes, resistors. Does anyone else keep stock like that, or just order what's needed when it's needed?
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Last night I checked out a few things. First I tried heating up that capacitor and powering on. No change. Then I checked that resistor. It's supposed to be 600Mohms, and my meter being auto ranging showed it as 1.2. I'm not sure what that means, but it's showing resistance so I assume it's good. Last I checked that transistor. I was getting funny readings from it (different measurements between base/collector as base/emitter) so I replaced it. Also NO CHANGE. I still am getting power cycling and that buzz/tick sound in the video I shared earlier.
Whatever is bad literally prevents the whole board from powering up, and instead it just "reboots" over and over.
I forgot to check DM871 on the bottom of the board. I seen Hamie's thread about it being a common failure for this model power board. Despite being surface mounted, I still have to remove this diode to check it, correct?Last edited by x_orange90_x; 02-20-2024, 06:00 AM.
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Go ahead and check that diode in circuit, if it gives unexpected reading then you might need to unsolder to see, not sure what you mean by 1.2 on the resistor, they should be close to the rating of the resistor, if unsure maybe de-solder it and check.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Originally posted by nomoresonys View PostGo ahead and check that diode in circuit, if it gives unexpected reading then you might need to unsolder to see, not sure what you mean by 1.2 on the resistor, they should be close to the rating of the resistor, if unsure maybe de-solder it and check.
I will check that diode though. HOPEFULLY that is it.
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Can you narrow down the location of the buzz-tick, maybe with a straw to your ear or such, make sure ALL the solders are good on bottom of board.SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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Originally posted by x_orange90_x View Post
I honestly don't know either! That's how my meter displayed it. 1.2 with the ohms symbol. I think it's probably okay though.
I will check that diode though. HOPEFULLY that is it.
SIGNATURE
Basic powerboard testing, most troubleshooting starts there: https://www.youtube.com/watch?v=4v8DcqCNG4A
Don't forget to inspect solder joints on underside of powerboard and check for obvious damage, often overlooked but simple procedure. Just be sure the high voltage capacitors are discharged, youtube has many videos on the subject, 400 volts can KILL, using a screwdriver to discharge capacitors is something I would NOT advise: https://www.youtube.com/watch?v=aEupCE9btEU
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