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Equipment Repairs => LCD TV forum => Topic started by: mali67 on May 21, 2012,15:11:08

Title: 32LV713B sound but no picture
Post by: mali67 on May 21, 2012,15:11:08

Hi, i have a Toshiba  32LV713B, it has sound but no picture, there is a picture if i shine a torch at an angle on the screen.
Ive checked the voltages and all seem to be correct.
Ive changed the inverter board for another it made no difference, convinced it was still the inverter i had another sent out from the same guy. he assures me they were tested and working.

Am i missing something or is it looking like the backlights them selfs?

Any help would be appreciated , thanks

Title: Re: 32LV713B sound but no picture
Post by: jordan on May 21, 2012,15:51:27

 :sign0085:

Title: Re: 32LV713B sound but no picture
Post by: mali67 on May 21, 2012,16:21:47

thanks for the manual, but all voltages are fine

Title: Re: 32LV713B sound but no picture
Post by: mulja on May 22, 2012,07:23:39

Hi
did you have "power on" voltage to inverter and "dim" voltage
did you have no backlight or no picture?

Title: Re: 32LV713B sound but no picture
Post by: mali67 on May 22, 2012,09:54:20

Hi, thanks for your reply.
i have on voltage of 3.4v
and dim voltage of 0v
hope that helps

Title: Re: 32LV713B sound but no picture
Post by: mali67 on May 22, 2012,10:27:30

i have picture
no backlight

Title: Re: 32LV713B sound but no picture
Post by: mali67 on May 22, 2012,11:52:47

any ideas as to why i have 0v on the dim side?
i have tried tracing the dim section on the board, but not making much sense of it.

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,02:36:59

Im still stuck with this one. if any ideas

Title: Re: 32LV713B sound but no picture
Post by: Keith on June 01, 2012,03:56:55

Is there any output from the inverter transformers?

Keith

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,04:05:03

i cant say keith as my meter isnt good enough to test.

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,04:25:40

just to add i have checked both primary and secondary windings of the transformers and both seem to check out ok

Title: Re: 32LV713B sound but no picture
Post by: jagbogah on June 01, 2012,11:07:14

Hi, i believe dim voltage is produce by Q104 through R112.
DIM -- Max = 3.2v.
g/lock

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,12:39:39

i have no voltage to Q104 or R112

Title: Re: 32LV713B sound but no picture
Post by: Ohm Supplies on June 01, 2012,13:43:03

Hello,

I think your neon will do to test for voltage.

is the inverter VIT71884.00?

Regards
Andy

Title: Re: 32LV713B sound but no picture
Post by: jordan on June 01, 2012,13:56:06

Look on scheme of Digital Power DVDD 3V3  voltage regulator U-104 and C-117(470uF/10V) ... ...U-104  entrance 5V SW exit 3,3V that waters Q-104 or R-112
My bee need only resolder tis metal (Vout 3,3V)on power regulator U-104

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,17:34:42

Quote from: Ohm Supplies on June 01, 2012,13:43:03

Hello,

I think your neon will do to test for voltage.

is the inverter VIT71884.00?

Regards
Andy

yes andy thats the correct inveter.
and jrdan ill check that now
cheers guys

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 01, 2012,17:41:32

those voltages are correct on u104 jordan , just no voltages at r112 or q104

Title: Re: 32LV713B sound but no picture
Post by: watteau on June 02, 2012,04:58:00

Hi,
Have you tried taking the 'DIM' lead out of the plug to the inverter, and applying, say,
3V to the DIM inverter board pin, to see if this brings up the backlights?
Possible the DIM from the main PCB is causing the problem.
Has the inverter PCB a ribbon cable to the LCD control panel?,
I have had problems with this type of arrangement where the control PCB was causing
the backlight problem.
Good luck,
John

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 02, 2012,05:23:23

yes tried that, but thanks

Title: Re: 32LV713B sound but no picture
Post by: mali67 on June 03, 2012,13:34:50

solved it was actually the backlights, changed some out of a samsung screen