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Help Required. No Picture, Got Sound, Got Backlight

sv2evo

Standard Member
Hi all,

47" Wharfedale TV. Got backlight and sounds, don't have picture. Feed has no impact, whether from HDMI, or anywhere else.

I have taken it apart, and noticed the following:

  • Visual check of capacitors for bulge/leaks ok
  • Everything else as it should be

Going one step further, when I disconnect the TCON board cable and reconnect, I get the picture back perfectly for 10 seconds or so, and then it dissapears. It goes off gradually, like an invisible hand is sweeping it away.(not in a all at once fashion).

From reading online, I either need a TCON, main board, or inverters. However, I would like some help to narrow it down a bit...

:lease:

Many thanks in advance!
 

JayCee

Distinguished Member
Report back with the number printed on the power pcb...and the model no of the Tv?
 

sv2evo

Standard Member
The model number is LCD47F1080P.
I am at work so can't check the power pcb number, is this significant?
 

sv2evo

Standard Member
Power Supply Board is 17PW17-4

TCON is V420H1-CO7

Mobo is 17MB26-2 followed by 260207

Master Inverter is VIT70042.50 Rev3

Slave inverter is VIT70042.51 Rev3


I have measured every cable coming in to the inverter from the mobo and I get 12V on some, 3.5V-ish on others and some signal values 0.7V, 1.2V, 0.3V on others. I was under trhe impression that I should be getting 5V +-10% on one cable at least?

I am now reading that some TCON boards are indeed fed by 12V DC. It seems that the power supply is working ok and that the TCON board is suspect...?
 
Last edited:

JayCee

Distinguished Member
If the backlight stays on that rules out the invertors.
Check C877/C878 on the psu pcb (usually 15nF/630v)...on some models these have been substituted with a single 33nf/630v cap.
you would need to measure them with a capacitance meter or just replace them if you don't have a meter.
 

sv2evo

Standard Member
Thanks for the comment, will do so when I get home. I am intrigued, how did you come up with the suggestion above? Is it a common fault or did you deduce it from the symptoms I have described?
 

JayCee

Distinguished Member
sv2evo said:
Thanks for the comment, will do so when I get home. I am intrigued, how did you come up with the suggestion above? Is it a common fault or did you deduce it from the symptoms I have described?
These particular caps are known to cause problems on several variations of these Vestel power supplies...I'm not saying 100% that they'll be the cause of your fault but it's best to rule them out.
I've changed them many times on these chassis.
 

sv2evo

Standard Member
Tested C877 and C878 and both healthy:thumbsup:. Shame as it would have been a cheap and easy fix...

Any other ideas I can try?
 

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