Hello all, hope everyone is keeping as busy as possible and staying safe. I am in the midst of troubleshooting my television. It is a Sharp Roku TV, 50" model LC-50LB481U. Here's the deal...it powers up, no picture/blank screen, no backlights, but HAS sound. Performed the flashlight test. I can see the menu with the flashlight. I have it narrowed down to either the LED strips or LED strips or both. Tested the LED strips, 3 are good, 3 are bad. My first question is, would I still have some backlight being that 3 are good? I'm being told that "generally", they are all or nothing. In other words, I have the impression that they must "all" work to create some backlight, if one or more are out, they will not work at all. Is this correct? Can I get away with only replacing the bad LED strips or is recommended to replace all of them which I have been told? Secondly, I'm being told that I may also have a bad power supply board in addition to the 3 bad LED strips. I tested the LED connection where the cord plugs into the power supply board with a multimeter. However, the power supply board does not state what the operating voltage needs to be when testing. Some do, some don't, and I do not see that mine does. It is no where to be seen in the owner's manual nor can I verify it searching the web. Anyways, it did show as 63.9-64 V on average on the + terminals. Does this sound about right? I am simply trying to determine if the power supply board is good or bad before proceeding forward. Thanks in advance for the helpful replies.
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Re: Power Supply and/or LED strips
With a bad led strip, the led power supply will detect the problem and shut down, 64 volts is just the base voltage, there will be a boost circuit that will increase it when its working properly. It is best to replace all the strips, or you will just likley be having to repair it again, and every time you remove the lcd you risk damaging it. -
Re: Power Supply and/or LED strips
Backlight failure is pretty common in that model and a little bit of navigation to turn down the backlight level. Even low power mode runs them at 78%. I would replace all strips with new. https://techhometravel.com/turn-down...l-in-roku-tvs/Last edited by neilc6; 04-14-2020, 07:39 PM.Comment
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Re: Power Supply and/or LED strips
Thanks for the advice guys...it sounds like you two aren't too concerned with my power supply board then?Comment
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Re: Power Supply and/or LED strips
These power supplies are good quality and the led drive circuit is fairly simple, maybe in few years things will be different.Comment
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Re: Power Supply and/or LED strips
I've replaced strips on that model at least twice. One had a repeat failure with a repaired strip and turning down the backlight. Only see bad strips cause power supply failure in a few cases - one particular Samsung model and a few Toshibas.Comment
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I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump
One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy... -
Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
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I once tried to get a ZD-915 desoldering station to work on a 18 volt battery power supply but unfortunately things did not go well but I did find a work around but I might try this idea again but going at a little differently more about this another time... -
The sub developed a constant popping every couple seconds from woofer and power LED flickering with nothing but wall AC connected. Connecting an audio cable didn't change anything. It doesn't play but a second or two of audio in between the pops.
Opened it up and discovered the power supply is making a faint clicking or ticking sound.
I measured the amp's output to the woofer and it pulses up to 50mv DC to be driver. The pulses coincide with the power supply ticking/clicking.
I measured the power supply output going to the amp board and it too has this pulsing. Voltage cycles... -
Hello Everybody,
Trying to repair a power supply from a Russound CA4 Multizone Controller (picture attached)
Russound no longer supports it but were kind enough to provide a schematic of the power supply (pdf attached).
The outputs marked 12v and 20v are all measuring only 1v.
The board is clicking, which I think means it is in something called hiccup mode when the flyback transformers switches because of an internal problem or something else on the board Overloading it.
The capacitors physically look clean (no bludgesor leaks) and...
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