Question about JVC LT-37X776 37 in. LCD HDTV

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High pitch whining noise constantly when TV is on or off after cable card instaled.

This started after I had a cable card installed in my TV. The owner manual says the fan will continue to rotate when TV is turned off. However, it is making a very annoying high pitch whining noise. How can I get rid of the noise? If it is from the fan can it be replaced with a low noise fan? If I switch power off to the TV will this harm the TV?

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SOURCE: Loud, high pitched hum from speakers . . .

This is GroundNoise from the TV's Backlight.

Sorry, but unless you are a Technician, you will simply need to ignore it.

If you are a technician, you can fix this by grounding the Audio ICs to the Power Supply (details not provided)

Posted on May 18, 2009

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SOURCE: LT-42P300 won't turn on. When I plug it in I


You might wish to unplug the TV for an hour or more. If this power reset does not allow the TV to turn on component failure is indicated. These sets are assembled using the wave soldering process they are known for having cold solder connections.

The safety circuitry shuts the TV set down or will keep it from turning on when it detects a problem. This model of TV has over 2,000 parts, which includes millions of transistors inside the integrated circuits. The capacitors will change value, leak and become defective. Resistors will change value and burn. Diodes and IC can go bad.

This may have a domino effect and cause other parts to fail. Replacing one defective part may make the TV operate for a short time but the part will fail again if the parts that caused the failure to begin with are not replaced.

The only way to know for sure which parts that are no longer within factory specs and for a proper repair all the electronics must be diagnosed by someone with the correct electronic test equipment specifically designed for TV service and the skills to use the test equipment. I wish I could tell you there was a quick fix or button to push that would fix the TV but that is not the case or the solution needed to get the TV operating correctly.

The issue you describe is consistent with a power supply board issue. This is the board where the AC goes to. This problem may have occurred as a result of irregular power supply, or excess power supply or power surge.

The TV is receiving current but cannot circulate or transfer the current to other necessary part of the TV because of the defective power supply board. You might be lucky it's just a blow fuse. Also a defective transformer can cause your TV not to power on.

All these can be checked on the power supply board.

But more often bad capacitors causes problem on the power supply board. I do not think the power board needs replacement, rather those defective capacitors is causing this issue. Open unit up and take a look at the power supply board.You will probably see one or more electrolytic filter capacitors that are bulged up in the top-not perfectly flat like the others.

The value of these capacitors will be different, most likely they will be somewhere around-820 to 2200uF/25 V( or /10V sometimes)

You can replace them with same values but I would recommend the voltage rating to be higher(like 35V for an original 25V) for reliability purposes.

What happens is,these bulged top capacitors will cause a low and unfiltered DC voltage=main board will malfunction(the relay will keep clicking until the caps are holding enough charge to bring the voltage up over a threshold point).

You can buy these capacitors at any Fry's or Radioshack store or you can order them online at vendors like ""(look for electrolytic capacitors). After replacing these capacitor(capacitors) most likely the normal operation will be restored. Or you can by a refurbished complete power board to save you some stress.

Note: There may be also some other causes for this symptom ,like a defective T con board ,or main board,but the bulged top capacitors are the most common cause for this issue.

If you don't know about TV repairers, take the TV to the nearest repairman to fix the fault for you. Also, note that TV stores a lot of current, so wait a while before opening the TV back cover.

I hope this helps.

Posted on Jul 11, 2011

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Hello randapaint,

This might be from the IHVT (Integrated High Voltage Transformer), or more specifically a short in the IHVT causing it to arc, producing the high pitched whine, you are hearing. Take the back off of the TV and try to detect where the sound is coming from, more then likely you will notice it coming from the section that contains a large component with a large red cable coming from it, to the top of the CRT (picture tube). Replace the IHVT (with the exact same model) if it is bad.

I hope this helps,

Thank you,


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