# JVC TV no power.



## Wally7

I have a JVC, JLC37BC3002 LCD TV. Does not power on, no standby light, has 5volts, no 12 volts, (I think 12v won't appear until unit is on) all capacitors on PS and control bd look good. Any ideas aside from changing Control board or power board.


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## Dude111

Welcome to the site Wally,im sorry your havinng problems......

Is there a fuse in the unit that might be blown???


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## Wally7

Both fuses are good.


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## Wally7

I can't find a schematic anywhere, even JVC say Model not found, but, they have the ops manual with the same Model #. JCL37BC3002


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## Wizmo

*Hi Wally,

If this is the same as my neighbor's "JVC" model, it is actually made by GoldStar! I had to replace the power board in his unit after a lightning storm took out the local transformer on the pole adjacent to his house. This is fairly common with these units and the power supply board is the usual suspect.* :sad:

*I've repaired several of these similar models and every time (so far) the power supply board was the culprit. Only saw a blown fuse ONCE, the rest had just a bad component somewhere that did not open the fuse.* 

*There generally is not a lot of service information on these things, but usually a part number is on the edge of the board that will come up in a search online as valid.*


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## Wally7

I have a JVC, JLC37BC3002 LCD TV. Does not power on, no standby light, has 5volts, no 12 volts, all capacitors on PS and control bd look good, fuses r good. Any ideas aside from changing Control board . The power bd has Vizio stamped on one side of the board and LG IT on another. As far as I can see I have all the voltages on the power bd. Only voltage on the cable to Main bd is 5V, but still no standby light, the on/off switch has no effect at all. the set never turns on. I suspect the main bd, is there any way to check it. Bridge Rectifier has 165V, 12v rectifier = 16.72v and 5.10v. I'm at a loss now,﻿


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## Wizmo

*LG is an OEM provider for LG, Vizio and JVC products, among others:

**Lucky Goldstar*
Well, LG stands for *Lucky Goldstar*. It is the abbreviation of the company's tagline, “*Life's Good*". LG Corp. is a conglomerate in South Korea that deals in the production of telecommunications products, chemicals and electronics.
https://www.google.com/url?sa=t&rct...s/83672.aspx&usg=AOvVaw0g6OxmZyDk3kD3PuAbiNSQ

*If the standby lamp is not lit, it is usually a power board issue. I have replaced power boards in many products in all three of the above mentioned brands with good results. No 100% guarantee, but 90+% certainty it is the power board.

There is little service information available on these units, so it is a process of elimination in most cases. Normal service facilities have stocks of these boards to do the troubleshooting. You will have to try the most common failure item (power PWB) with a 90+% likelihood it will solve the problem. :wink:

There are "opto-coupler" circuits on the main power PWB that control the power outputs. These provide isolation from the AC line voltage input generally. Often it is a failure of one of those components that causes the "dead set"** symptom you have. Absent a stock of readily available replacement boards, your only option is to try it. These boards are generally available for between $65-$95 depending upon the source.

Best of luck! :grin:
*


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## Wally7

No standby light would be a power issue, but i have 5v standby voltage on the cable going to the main board.


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## Done_Fishin

Standby Voltage is just a voltage that supplies the microprocessor with power when the set is in Standby and is independant of all other voltage rails. Apart from the possibility of having a power Supply fault, as already said, There is a possibility that the microprocessor isn't running for a multitude of reasons which include crystal is not oscillating, stuck in reset, failure to load firmware from eeprom, corrupted data in eeprom, corrupt or faulty memory .... and the list goes on !!

Either obtain some known working boards and swap them out to see what board has failed or find a way to fault find the processor board to see if there is anything missing. 
As far as boards are concerned, purchasing second hand boards can be very hit & miss, They are supposedly tested and many are take from scrap units after the display gets trashed. I remember trying to repair my brothers set which was stuck in standby & I figured it had problems on the processor board. We ordered a board and when I fitted it, it too had the same problem of being stuck in standby but caused by different fault .. Whilst my set had voltages on 3 dc-dc switch mode circuits the supposedly tested board supplied didn't !


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## Wally7

Thanks, that was going to be my next step to attempt to find some boards to swap out.
Troubleshooting is a challenge without a schematic, which i found impossible to find and troubleshooting the Main board is also impossible.

As I mentioned previously, i have all the voltages on the power supply, so I think it is most likely the Main bd.


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## Done_Fishin

You may have all the voltages according to your Voltmeter but you have no idea what the ripple is like on the rails .. you could very easily have a problem with Electrolytic capacitors and that doesn't always show physically. Digital Multi-meters do not give instant by the millisecond readings, they average out readings taken and display the result once a second. There are also frequency limitations to the average reading so may not even see the spikes being generated.


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## Wally7

Well, I gave up my Oscilloscope many years ago, and the capacitors look good physically and, I'm not taking them out one at a time to check. I have old analog meters which show the charge of the cap. Even so, without a schematic there's no way to trace anything. I'll have to find boards and shot gun trouble shoot.
Thank for your help


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## Wizmo

*Hi Wally,*

*You don't show your location, so I cannot speculate on cost of boards & shipping. However I can give you "odds" based upon the 23 JVC/LG/Vizio sets I have encountered. Being out here on an island, ordering & shipping parts is expensive. I got lucky with the first 4 sets I encountered as all were with me at roughly the same time, and I was able to determine that all 4 needed only the power board. I ordered 3 more and was done with all 4. The time with a set with BOTH boards bad, I had similar sets in at the same time and was able to swap the boards around! :smile:*

*I do repairs for two local (competing) wholesale clubs, which gives me the opportunity to see these more regularly than most.*

*I won't distinguish by brands, as they all had the same or similar LG produced boards:*

*(19) sets repaired with only the power PWB*

*(1) set scrapped due to severe screen defects (was a handy parts source for others!) I use those parts for troubleshooting other sets in a still ongoing process.*

*(1) set repaired with both the power and logic/control PWB's*

*(2) sets beyond economical repair (total destruction by lightning)*
*Unfortunately one of these was my personal TV! :nonono:*

*This has been my experience. We have diesel generated power here and have frequent surges and sags, which contributes to the stress on power supplies. It's that way with pretty much all electronics here. Your situation may be different, but the power boards still seem to be the "weak link" in most cases. :frown:*

*I had different symptoms at various times - standby light on in some, off in others. Some output voltages present, some missing. The one with both the power PWB and logic PWB had the standby light on at all times. Others it was about a 50/50 chance of seeing the light.*

*Based upon my experience, I'd try the power PWB first. Your Mileage May Vary [YMMV] :wink:*


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## Wally7

I'm in the north east coast of USA. I don't have the luxury of having multiple sets to repair at one time. I'm doing my daughter a favor. The last time I repaired a TV was in the tube era. Then, you had to troubleshoot down to the component or just replace a tube.
By your experience sounds like the power supply is my first move, it's also the cheapest, i think around $50:00. Thanks for the stats. Get yourself some solar power, I think you have plenty there.


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## Wizmo

*Hi Wally,

My only solar enhancement is (3) 55 gallon food-grade drums in the attic, which provide me with 165 gallons of *FREE* hot water on demand - year round. Due to adverse conditions regarding solar implemented by government in "cahoots" with the local monopoly utility, solar is being discouraged in an area where it could be a primary source of power. :nonono:

Politricks as usual... "To err is human, to really screw things up requires GOVERNMENT!" :facepalm:

Yet another quotable for you to enjoy...
*


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## Confounded Also

> JCL37BC3002


Don't know when she got it, but the manual I found has a copyright date of 2012. That could make the set going on six years old. If you just want to fix it because you prefer to fix things, that's fine. No problem there, but she'll still have an older set. Five years is ancient in the field of televisions now.

New sets 37" and larger can be had for a couple of hundred dollars now if you watch the sales and promos. Buying and swapping parts in hopes of find one that works could cost that much or more, not counting your time. There's also no guarantee that fixing one thing won't find other problems, or that there isn't more than one part bad to begin with.

It's become almost pointless to try to fix consumer grade electronics. They're just not made to last any more.


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## Wally7

It's about 5-6 years old. You're right, of what i've been reading it seems whatever part is replaced it doesn't seem to fix the problem the first time around. I was just curious, initially i thought it might have been a fuse due to the symptoms. And, the PS board cost is around $50, a new logic bd is around $150. US. So, yes, take that money and put it toward a new TV is a better investment.


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