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Old 01-28-2010, 09:31 AM   #41
Wizard
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Default Re: Sony Bravia no picture but backlight on

Yes, 3A fuse.

Looks like you have a problem deeper than that, 2A is too small fuse and I have seen some that draw high current than 2A The marking says 3A and you have to use 3A fuse. Even my 32" panel 5V supply specifies 2.5A fuse for max of start up 1.9A, running 1.4A.

Cheers, Wizard

Last edited by Wizard; 01-28-2010 at 09:35 AM..
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Old 01-28-2010, 12:08 PM   #42
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

Quote:
Originally Posted by PlainBill
That means it is reading more than 200 ohms. 200 ohms is greater than the 80 ohms Wizard mentioned. This means the cap isn't shorted. This is good news, you have eliminated the caps as a possible problem.

And I notice you STILL haven't answered the question - what was the rating of the replacement fuse?

I'm not trying to dump on you, but it's obvious you don't have a strong electronics background. I'm trying to make sure the simple things are correct.

PlainBill
The original is a 3A. The replacement was also 3A, but that burnt.
I'm going to change the fuse again and will then start testing the smd's again as hardwareguy suggested.
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Old 01-28-2010, 11:09 PM   #43
hardwareguy
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Default Re: Sony Bravia no picture but backlight on

DO NOT add another fuse! Find the short FIRST!

Repeatedly blowing fuses could harm the system as the system will be repeatedly subject to overload.

If it reads 1.0 on the 200 ohm scale....are you sure thats not OL or something?

1.0 on my meter means 1.0 ohms....and if you get that on an MLCC cap, its dead.
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Old 01-29-2010, 05:14 AM   #44
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Default Re: Sony Bravia no picture but backlight on

Quote:
Originally Posted by hardwareguy
DO NOT add another fuse! Find the short FIRST!

Repeatedly blowing fuses could harm the system as the system will be repeatedly subject to overload.

If it reads 1.0 on the 200 ohm scale....are you sure thats not OL or something?

1.0 on my meter means 1.0 ohms....and if you get that on an MLCC cap, its dead.
You are definitely right about simply replacing the fuse. It's blowing for a reason. As far as the resistance, take a look at the picture of the meter. It's on the resistance scale, the leads are not shorted and it's displaying 1 . (First digit 1, three spaces, then the decimal point).

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For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.
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Old 01-29-2010, 09:53 AM   #45
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Default Re: Sony Bravia no picture but backlight on

let me clarify, first I'm changing the fuse in order to start testing the ceramic smds again. For now ALL the smds do not cause the meter to react in any way. When I turn on the meter and set it on 200, it displays 1.
This reading doesn't change at all when I touch any smd. However, when I touch the two ends together, it give me a 0.4reading.
So I'm hoping that by first changing the fuse and then doing the readings, it might change something.
BUT I WILL NOT ATTEMPT TO PLUG THE BOARD BACK ON THE TV UNTIL I"VE FOUND THE CULPRIT
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Old 01-30-2010, 07:40 PM   #46
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

So, I replaced the fuse and started testing smds again but the meter still isn't reacting when I touch the ends to the smds. Am I doing something wrong?
Please see pics below of the meter when the ends are not touching, when the ends are touching and when I try to test two smds.
Maybe the meter is faulty? I have another meter but doesn't have a setting at 200...
Attached Images
File Type: jpg ends not touching.jpg (122.9 KB, 55 views)
File Type: jpg ends tuching.jpg (125.5 KB, 44 views)
File Type: jpg no reading 1.jpg (133.2 KB, 77 views)
File Type: jpg no reading 2.jpg (133.1 KB, 70 views)
File Type: jpg another meter.jpg (127.9 KB, 54 views)
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Old 01-30-2010, 09:43 PM   #47
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Default Re: Sony Bravia no picture but backlight on

Quote:
Originally Posted by bobbyvalentino1978
So, I replaced the fuse and started testing smds again but the meter still isn't reacting when I touch the ends to the smds. Am I doing something wrong?
Please see pics below of the meter when the ends are not touching, when the ends are touching and when I try to test two smds.
Maybe the meter is faulty? I have another meter but doesn't have a setting at 200...
To mangle Wm Shakespeare '“The fault .... lies not in our meters but in ourselves.”
Follow this logic.

The T-Con board gets it's power through that fuse.
It converts the power to drive the LCD display, as well as using some for itself.
One thing that can go wrong is a SMD cap shorts, loading the power line, and blowing the fuse.
Per Wizard, when that happens the cap will have a reading below 80 ohms.
You do not find a cap with a reading below 80 ohms.
Conclusion: None of the SMD caps are shorted. (Just for luck check ALL SMD caps)

Other possible causes of this problem is a fault in one of the ICs, a fault in the voltage converter, a bad inductor, a fault in the LCD panel. One thing that helps troubleshooting this is the total current through the fuse is only a little over 3A.

PlainBill
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Old 02-01-2010, 12:19 PM   #48
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

so, I've gone as far as my limited knowledge permits me...
I will be ordering the t-con online. However, there is a minimum quantity order, so I will need to purchase more than one item. What other boards are known to fail on this tv? I'll order that board too!

Last edited by bobbyvalentino1978; 02-01-2010 at 12:20 PM.. Reason: spelling mistakes
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Old 02-01-2010, 12:39 PM   #49
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Default Re: Sony Bravia no picture but backlight on

My board is still on its way. It should be here tonight or tomorrow. I'm pretty anxious. I really hope it fixes it after all this time. I got mine from Discount-Merchants for about $50 (again, I was the one with the Original tv in this post, a 32" Bravia)
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Old 02-01-2010, 10:14 PM   #50
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

I order my t-con today.
I got it from Mat Electronics for $9.95!!
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Old 02-01-2010, 10:44 PM   #51
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Default Re: Sony Bravia no picture but backlight on

Holy crap!! Really!?
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Old 02-02-2010, 08:21 PM   #52
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Default Re: Sony Bravia no picture but backlight on

HEY HEY!! I got my T-Con board today. 15 minutes later I was looking at one snazzy working tv. I still don't know what was wrong with the old board, but at least with all your help I narrowed it down.

Thanks a lot everybody for your help!


and best of luck fixing your own
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Old 02-02-2010, 09:30 PM   #53
Wizard
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Default Re: Sony Bravia no picture but backlight on

Awesome! I knew that would fix this (higher chance of success).

Cheers, Wizard
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Old 02-03-2010, 12:16 PM   #54
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

I wish I have the same luck. I'll post the outcome when I get my board and install !
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Old 02-20-2010, 09:51 PM   #55
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

So, I got the replacement board, installed it but the fuse popped again.
Can any other board be burning the fuse?
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Old 02-20-2010, 10:25 PM   #56
Wizard
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Default Re: Sony Bravia no picture but backlight on

Panel totally failed sorry to say. Also make sure the LCD voltage is 5 or 12V is within range. If not. Time for a another panel or new TV.

Cheers, Wizard
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Old 02-21-2010, 08:20 PM   #57
bobbyvalentino1978
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Default Re: Sony Bravia no picture but backlight on

how do i verify the voltage?
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Old 09-27-2010, 11:00 PM   #58
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Default Re: Sony Bravia no picture but backlight on

Got same problem on the 52" version. So I will keep tabs on this, for when I get around to getting new T-Con board.

Same thing, as first poster, BL works fine, actually even picture came on once just from moving connectors, get audio out from all the HDMI jacks, but no picture.
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Old 09-28-2010, 01:14 PM   #59
PlainBill
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Default Re: Sony Bravia no picture but backlight on

Quote:
Originally Posted by BCR View Post
Got same problem on the 52" version. So I will keep tabs on this, for when I get around to getting new T-Con board.

Same thing, as first poster, BL works fine, actually even picture came on once just from moving connectors, get audio out from all the HDMI jacks, but no picture.
That indicates a bad connection - either the cable itself, or on the board the cable connected to.

PlainBill
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Old 09-30-2010, 01:56 PM   #60
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Default Re: Sony Bravia no picture but backlight on

The cable is good, it is a 1 meter cable that I use everyday on the PS3 straight to other TV, but I did try a second cable to be sure. As well, went around every board on TV and checked connections, all look good (some grease, but that is standard).
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