Samsung LE40C580 no sound/picture, but backlight on

[ikershaw]

I'm wondering if anyone can help me. I have an 18 month old Samsung LE40C580 LCD TV which has stopped working.

Connect mains power, red power LED flashes on and off. After about 5-6 seconds, white light can be seen if you look through the rear vents (assume backlight is working?). Pressing the power button on the remote causes it to flash but nothing happens.

There's no clicking sound of power relay coming on, when connecting to mains or pressing power on remote.
There's no sound (it's connected to TV ariel)
There's no picture (just black).

It has been to a local TV repair shop who produced a repair report which I'm using to try to get original retailer to repair under EU law. Unfortunately, this is turning out to be a protracted battle and so I thought I would look at fixing it myself.

The report said "faulty T-Con" so I have purchased a salvaged T-Con part, carefully matching the part numbers, and replaced this in the TV but it's exactly the same. I guess there is a chance the replacement T-Con is also faulty.

Any suggestions? Otherwise, it's off to landfill and new TV time as repair is half the cost of a new set and comes with no guarantee.

Thanks in advance.

[selldoor]

Re: Samsung LE40C580 no sound/picture, but backlight on

I dont know about landfill - there are a few members who may gladly take it off your hands to play with. I would also thought you should have some sort of claim a tv should last longer than 18 months.
I dont know much about tvs hopefully someone who does will be more use. In the meantime
Welcome to the forum-
We can often help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.

[selldoor]

Re: Samsung LE40C580 no sound/picture, but backlight on

Perhaps check out this thread - shows where to test fuse on Tcon.
https://www.badcaps.net/forum/showth...light=LE40C580

[vinceroger69]

Re: Samsung LE40C580 no sound/picture, but backlight on

maybe try a factory reset
Samsung *****************************************-

(with tv is off) Mute 182 power using the remote control
(On some models, Factory Reset is on this menu, on some, you must go into the “Options” submenu

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Thanks for the replies and for the warm welcome. I'm a software engineer with a passion for fixing things. I'm reasonably handy with a soldering iron and have a digital multimeter. I've fixed a few things, but had a few failures too!

I agree it should last more than 18 months and do have a claim underway which the UK European Consumer Centre is pursuing on my behalf, unfortunately the supplier is playing hardball and it's been 5 months since the TV went wrong so I've decided to give fixing it a go otherwise it's new TV time (getting it repaired doesn't seem sensible when it might just go wrong again a few months later).

I've tried the reset as suggested. It didn't seem to do anything and the red led did flash when pressing the buttons on the remote.

I've checked the fuse with my DMM on both the original and replacement T-Con boards and it's fine. I'm impressed you found that thread, as I scoured these and other forums before posting here! It does seem to be a very similar problem, but I've no sound (but I guess that could depend whether it has a valid source).

I've taken pictures of the panel and boards as requested (PSU top view and side view - showing capacitors appear to be fine).

Any suggestions welcome, I've really no idea how to fault find something like this.

Cheers,
Ian.

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Oh, and this is the replacement TCon I got.

I guess it could also be faulty or even the wrong part? But I did check the fuse.

[budm]

Re: Samsung LE40C580 no sound/picture, but backlight on

No SAMSUNG chime when it is turn on?

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

No Samsung chime, but it never chimed when it was working...

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

I'm guess due to lack of responses that we're at a bit of a blank with this one. Does anyone have any suggestions what to do next? Professional repair, landfill or wait for retailer to repair I guess?

Thanks for everyone's efforts.

[tom66]

Re: Samsung LE40C580 no sound/picture, but backlight on

Wait a second, so it died at 13 months? Seriously? I would have thought you would have had an immediate claim.

Service reset for European Samsung (for future reference):
(TV in standby) Info, Menu, Mute, Power then select Reset.

However, as you have no image, you would not be able to do this.

Can you measure the voltage at both ends of the fuse with respect to the chassis, with the TV both in standby and working.

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

It was about 18 months, but that was nearly 6 months ago. Been disputing with retailer since it went wrong and without a telly since then!

I could probably measure the voltage in standby, but not when it's working since it doesn't ever get into a state I could call working (it seems to power on the backlight without pressing any buttons). What would I be looking for?

[selldoor]

Re: Samsung LE40C580 no sound/picture, but backlight on

I think tom may be referring to the fuse on the Tcon -With it all connected up and on
(as far as it will go on) Meter on 20vDC black lead on ground (metal part of the LVDS cable connector) probe each end of the fuse with the red probe.

Whilst wondering if that was the fuse tom meant I noticed a fuse on the power supply board - the one by the power cable must be ok but there is another by the yellow capacitors. WITH POWER OFF check it for resistance or better still remove it and check it - if it comes out easily.

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Thanks, I'll try this.

With regard to checking those PSU fuses, do I need to discharge those yellow 450V caps or just be very careful? If I do need to, use something like this? http://lifehacker.com/5935955/diy-ca...discharge-tool

Cheers for help with this!

[selldoor]

Re: Samsung LE40C580 no sound/picture, but backlight on

You are right to ask - working normally most caps will discharge themselves to a non lethal level in a few minutes but this set is not working normally.
You could use a discharge tool - personally I would wait a few minutes then
check the big caps with your meter on 600 vdc and see what voltage remains.

Equally you could check for a voltage from the negative leg of the big cap to each end of the fuse before doing the test.

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Thanks selldoor - this makes sense. I'll look into this tomorrow and come back to you (or not, if I zap myself with 100μF of finest distilled lightning bolt).

[tom66]

Re: Samsung LE40C580 no sound/picture, but backlight on

If the backlight is on, those caps should discharge quickly.
HOWEVER!!
I have had a nice 160V shock from one of those caps before. One particular TV would run that cap down (after being unplugged) to 160V then stop, so the cap would sit at that voltage for days...!

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

OK I've just tested the voltage and luckily for me there were no blue flashes or green smoke. I tested the voltage on the yellow caps one each leg and it was 0V (but it's been off a few days).

So... I got a reading of 12.42V on the TCon fuse/chassis test (for both TCon boards I have). Both PSU fuses are fine, I took the one out that you mentioned to test. The voltage on the TCon fuse was the same before and after the backlight came on (which is does after about 7 seconds of being connected to the power, without touching the power button on the remote).

Any ideas what next? Does it suggest TCon faulty or something else? (Always a chance I have two duff TCons!)

Thanks.

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Does the voltage mean it's good/bad? Anything else I should try?

[tom66]

Re: Samsung LE40C580 no sound/picture, but backlight on

12V is good.
I'd be slow to say your t-con was at fault but let's check some other things.

Capacitors CD27, CD28 store AVDD. I don't know what this will be; but I'd expect it's going to be 15~18V, given the output capacitor is rated "D", which codes for 20V. See this datasheet: https://www.badcaps.net/forum/attach...4&d=1357859920

Capacitor CD32 looks to be the input voltage to the buck or boost converter. I'd expect 12.4V, i.e. VIN.

Capacitors CD4, CD5 and CD6 look to be a 3.3V supply, is this correct?

(Note: For all the above, measure the voltage across the device, and from each end to ground. The across-device and one end to ground should be the same, with the exception of a sign difference.)

[ikershaw]

Re: Samsung LE40C580 no sound/picture, but backlight on

Thanks for the quick reply! Seems that datasheet link is to the picture I took of the T-Con board?

Agree with T-Con not being prime suspect, since I've tried a replacement board. But I guess that could also be faulty!

I'll check the voltages and come back. Are all these CD components on the TCon board? And to check, I test against +ve using the fuse, and for ground the cable connector chassis, right?

Thanks very much.