finlux (vestel) 42f701 3d lcd backlight but no picture

[charlierfc]

Hi all. i have the above tv, i have a standby light and when its turned on by the plug the red light blinks and stays blinking....the only way to turn off is by plug. It doesnt respond to the remote. the back light is on,but the screen is blank.when the touch buttons on the tv are pressed the tv beeps but thats it.
no sign of bad caps or anything burnt. im thinking main board?

[charlierfc]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

pictures..

[charlierfc]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

guessing its a bad regulator on the main board.iv ordered another and will update

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Hi! Sorry for bringing such an old thread back to life, but I have the exact same problem with my Vestel (andersson A376FDC PVR). Standby works fine, but when you start it you only get backlight and no picture, and it just beeps when you press a button on the tv. Pulling the plug is the only way to turn it off again.

The PSU in mine is a 17pw26-4, but the mainboard is verry, verry similar. Please, what did you find out?

[sordids999]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Tested all voltages ?

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Hi, thanks for the reply!
No, I haven't, for a couple of reasons:
1. I didn't see any caps that looked bad on the psu (I do know what to look for, I Have repaired a couple of TV:s and screens in the past).

2. I do not know how to know which pins to test for which voltage, or how to figure it out.

3. Measuring on a live psu seems dangerous....

4. It almost works: the initial standby when you plug it in looks normal, and you can start it with the remote or a button. Then the backlight goes on, first at full then dims a bit, and the standby-led is replaced by the power-led. This is where it stops. Backlight is on, so there does not seem to be a lack of power, and it even "beeps" when you push one of the button on the tv. But nothing happens and it does not respond to the remote.

Since charlierfc stoped reporting the problem after replacing some voltage regulator, it made me think that maybe it solved his problem, which is the only description similar to mine I've found.

TV specs:
Model: andersson A376FDC PVR
PSU: 17pw26-4
Mainboard: 17MB61-2

[sordids999]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

I'm not sure if he fixed his problem no follow up received
so maybe posting some clear pictures of the boards with the back off the tv may help you more with fixing your problem

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

These are all I have for now, I can take more when I get home.

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

So, I measured 4 large voltage regulators on the mainboard, and they all raised the input voltage by 1.25v as expected. This tells me two things: they are not faulty, and the MB is at least supplied some voltage.

I would love some feedback on how to measure the psu voltages while the system is on, and on what voltages to expect!

Picture of PSU attatched.

EDIT:
I also found this:

[tom66]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Is it a 17PW26 PSU?
http://www.toms-service-manuals.com/...h=Submit+Query

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Yes it is, thanks for the link! Will do measurements tomorrow. Is the metal case under the board a suitable ground?

[sordids999]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

yes black probe to chassis red probe to measure

[newtothis]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Gotta love these vestels!

I just replaced one in a finlux, couldn't be arsed repairing for a matter of £14 GBP

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Okay, so I haven't gotten around to taking those measurements yet, but I noticed something intresting. When connecting a USB drive to the tv a folder structure for DVR is created on the drive when starting the tv, so at least some of the intelligence in it is alive. Now onward to those measurements....

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

Ok, on to voltages:
3.3v and 5v standby are fine.
24v and 5v also.
3.3 on measures as 3.2 and 12 v on measures as 11.9. Could there be something wrong with the inverter board? I suppose that it is this thing at the top of the tv (attatched). What should i look for?

But I am not sure how this would explain that the tv in unresponsive to the remote and the buttons once it is powerd on...

[vinceroger69]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

could also be a main board issue too i guess whats the part number/sticker number on the main board?

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

The model is 17MB61-2, do you need more than that? There are some other stickers with numbers, there is a picture higher up in this thread, and two posts up from that is a full problem description. The main board is alive enougth to create files and folders on a usb drive though.

[vinceroger69]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

not sure if this is the right main board pdf but may help you take some voltage mesurements etc. Has the tv got any sound at all do you know?

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

I have measured all the incoming voltages from the psu, and they seem right. The tv makes a "BEEP" when you press one of the buttons on the side, but it is otherwise unresponsive to them.

I have also measured the 4 large voltage regulators on the MB and they all raise the input voltage by 1.25v as expected. I am not sure how to know if these input voltages are ok, though.
EDIT: found them in the diagram, will measure again soon.

[deeshu]

Re: finlux (vestel) 42f701 3d lcd backlight but no picture

U39, U18, U25 and U26 all output the correct voltages. I seem unable to find anything wrong with this tv. Could it be software-related?