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Old 01-09-2022, 05:14 AM   #1
freccia
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Default Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Hi all,
I have a Finlux/Vestel Led Tv with the following fault and cannot reason from where the fault is. Fault is:
Sound ok, Backlight ok, Picture nothing but colour vertical lines. power supply vestel 17 IPS 71, main board 17MB82S
Checked 12V on tcon on fuse ok.
Checked 12v and 24v on power supply ok.
Volume works. removed l left ribbon cable no picture white on half, and same with right one.
Any idea from where I can start please?
Any help appreciated please.
Attached Images
File Type: jpg IMG_20220109_112028.jpg (324.5 KB, 24 views)

Last edited by freccia; 01-09-2022 at 05:45 AM.. Reason: update details
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Old 01-09-2022, 09:21 AM   #2
freccia
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

About the photo take, please note that that is the flash not a broken display. Also volume works as sound not on scrren display.
24v measured on a capacitor on the secondary of the power supply.
Photo is taken with both tcon ribbon cables connected.
Also please find a photo of all the boards on this TV.
Thanks
Attached Images
File Type: jpg IMG_20220109_112409.jpg (893.4 KB, 20 views)
File Type: jpg IMG_20220109_112341.jpg (956.2 KB, 12 views)
File Type: jpg IMG_20220109_112333.jpg (791.2 KB, 8 views)
File Type: jpg IMG_20220109_112324.jpg (729.8 KB, 8 views)
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Old 01-09-2022, 12:21 PM   #3
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Doubt if this is your problem but need to check connector between power and main board for cracked solder joints. Then you need to take some voltage checks on t-con. Lower right corner for starts.
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Old 01-09-2022, 09:56 PM   #4
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Hi. thanks for your reply. Willcheck the solder joints between the main board and power supply. Will also measure the voltages at the test points on the right and come back with the readings.
thanks
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Old 01-09-2022, 10:49 PM   #5
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Ok. Here are the voltages from the t-con right test points:
VCOM 6.4V
VCOMR_FB 6.4V
VST -4.8V
VGL_1 -4.8V
VGH_EVEN 27.5V
VGH_ODD 27.5V
CLK1-CLK6 ALL 5.6V

Do you see anthing wrong or abnormal in these voltages please?
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Old 01-09-2022, 11:52 PM   #6
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Measured more voltages on Tcon
VCC 4.3V
VGL -4.8V
VGH 27.6V
VCOML_FB 6.4V
VA1 12V
HVDD 8.3V
VIN 12V
VDD 16.7V

Are these normal please?

Last edited by freccia; 01-09-2022 at 11:55 PM.. Reason: forgot the negative sign on vgl
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Old 01-10-2022, 11:07 AM   #7
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

I am stuck on this. Any help would be greatly appreciated please.
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Old 01-10-2022, 11:18 AM   #8
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by freccia View Post
I am stuck on this. Any help would be greatly appreciated please.
yours photo.. if you press menu or change source signal did you see some effect on those lines and color ?
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Old 01-10-2022, 01:31 PM   #9
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by freccia View Post
Measured more voltages on Tcon
VCC 4.3V
VGL -4.8V
VGH 27.6V
VCOML_FB 6.4V
VA1 12V
HVDD 8.3V
VIN 12V
VDD 16.7V

Are these normal please?
These look OK.
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Old 01-10-2022, 10:48 PM   #10
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by Diah View Post
yours photo.. if you press menu or change source signal did you see some effect on those lines and color ?
If I connect a dvd player on scart, I can hear the sound, but picture remains the same, no menus or volume is shown on screen. Volume loudness works though, just not showing on the screen.
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Old 01-10-2022, 10:51 PM   #11
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by freccia View Post
Ok. Here are the voltages from the t-con right test points:
VCOM 6.4V
VCOMR_FB 6.4V
VST -4.8V
VGL_1 -4.8V
VGH_EVEN 27.5V
VGH_ODD 27.5V
CLK1-CLK6 ALL 5.6V

Do you see anthing wrong or abnormal in these voltages please?
@DSKALL, do these other readings seem right to you?
Do you think that t-con is good?
I have no other boards to test with.
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Old 01-11-2022, 10:25 AM   #12
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

I would say they are all OK. Try partially removing cable to t-con and moving it around to see if you get any picture. You may have bad cable or connection between main and t-con.

Last edited by dskall; 01-11-2022 at 10:30 AM..
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Old 01-12-2022, 12:51 AM   #13
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by dskall View Post
I would say they are all OK. Try partially removing cable to t-con and moving it around to see if you get any picture. You may have bad cable or connection between main and t-con.
I tried to loosen it, I cleaned the contacts, but nothing,no change, picture never shows but remains as in sample previously attached. I will try to purchase a ribbon tcon cable and see what happens.
Thanks
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Old 01-16-2022, 02:30 PM   #14
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

One of the first and least expensive things you can do when you have an issue is take the powerboard out of the tv, flip it over and look the solder joints over with a magnifying glass if needed, add a little flux to make the solder flow well and add solder to any joints that look even a little suspect. You can practice on a scrap pcb board if needed, careful not to bridge any joints, and always let the board sit for quite a while or discharge the big caps with an appropriate resister before working on it (safety first) to try to keep from getting shocked, it doesn't take 1000 volts to KILL, a lot less can kill, so be careful, it's only a tv.
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Old 01-16-2022, 02:51 PM   #15
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Thanks for your message. I have checked for dry joints on the power supply. I have ordered the ffc cable. It will take a while to arrive. Will replace it and let you know if it is from that cable. All voltages look ok, at least from my previous posts, it may also be the tcon but voltages look ok in the exit side, maybe it has an issue when connecting to the main board, no osd though. Will let you know when the part arrives, seller posted it today, THanks
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Old 01-16-2022, 03:07 PM   #16
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

I would prolly throw another tcon at it if they don't cost too much.
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Old 01-27-2022, 12:44 PM   #17
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

I have changed the ffc tcon cable, saw the picture when i moved the cable but when i locked it in the same display with lines came up. Guess it is time to replace the tcon as well now.
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Old 01-27-2022, 01:02 PM   #18
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

That is a little strange, maybe try resetting those cables, might be just a slight bit misaligned, did you try resetting both the cable going to and leading out from tcon and the ones from tcon to panel driver board, can clean the contacts gently with isopropyl alcohol, some use a pencil eraser.

Last edited by nomoresonys; 01-27-2022 at 01:05 PM..
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Old 01-27-2022, 01:05 PM   #19
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Quote:
Originally Posted by nomoresonys View Post
That is a little strange, maybe try resetting those cables, might be just a slight bit misaligned.
moved it slightly outwards of the lock position, the picture came full but went after a few seconds, so i think that it is either the socket has something or electronically something is happening. new ffc cable installed and same syptoms. Did clean them with alcohol, the ffc cable socket, but in vane. also disconnected the 2 tcon ribbon cables going to the panel, but same picture with lines appear. I am thinking that maybe tcon is somehow resetting or removing a short when the cable is slightly loose. must be the tcon i guess. but it will take me 2months for it to arrive.

Last edited by freccia; 01-27-2022 at 01:11 PM..
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Old 01-27-2022, 01:09 PM   #20
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Default Re: Vestel 42 inch VES420UNDL no picture, backlight ok, sound ok

Check the solder joints on the sockets.
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