EEVblog #630 - Soniq LCD TV Troubleshooting Repair

[fluxcapacitor]

its most likely the T-CON thats faulty . The part number is : 6870C-0303B

[Jonny]

Use some of those high end scopes of yours and monitor signals into, and out of, that little board between the main board and LCD and compare data in with data out and might show if signals are failing coming out then that's your issue. If signals going in also appear to go unsettled grab the main board and make use of your reflow oven 

Looking forward to that video, nothing to lose 

[croyleje]

Just a thought but wouldn't the external VGA output be easier to probe and check the timing on or at least be able to see if there is a glitch from when the it is working and isn't working.  Also when Dave first kinda leaned over the tv and grabbed the side the pic dropped out seems like some kind of connection issue to me.  Just my thoughts.

Jason

[tom66]

its most likely the T-CON thats faulty . The part number is : 6870C-0303B

Disagree; the T-con going bad usually causes a number of specific problems. This T-con is also memoryless, it's an LVDS format converter. A fault where the boot logo is OK would not be one of those. The main board is the only part that can differentiate between these.

[fluxcapacitor]

its most likely the T-CON thats faulty . The part number is : 6870C-0303B

Disagree; the T-con going bad usually causes a number of specific problems. This T-con is also memoryless, it's an LVDS format converter. A fault where the boot logo is OK would not be one of those. The main board is the only part that can differentiate between these.

Yes ,you`re right tom . 

[NiHaoMike]

If the panel accepts the same data format as the broken one in that salvaged monitor, you could try using the driver board out of that monitor.

[pickle9000]

The EEVBlog curse is broken?

Hard to believe.

[VK3DRB]

You don't need an expensive differential probe to scope the primary side of the power supply. Just plug the TV into a mains isolation transformer, then you can scope it. For safety reasons alone, it should be mandatory to use an isolation transformer before even attempting to power the TV up with the back off.

You should consider using the back of a screwdriver to flex the PCBs slightly to see if the intermittency of the problem changes.

Another suggestion is to buy yourself a can of freeze spray and with a heat gun as well, see if the intermittency changes with cool/heat. If you see that it is changing, then use cardboard barriers to isolate the area where the offending dry joint or intermittent capacitor exists. This is a very effective technique for symptoms as those shown on the video.

From an ethical perspective, it is good practice to bias towards fixing something rather than throwing it away.

[Stonent]

its most likely the T-CON thats faulty . The part number is : 6870C-0303B

Had a cheap 32" 720P Westinghouse TV a guy at work was going to trash but said I could have it because I liked to play around with electronics stuff.  It seemed ok for about 20 minutes and then started bleeding red into the picture, then getting vertical red lines, then blocks.

I contacted a TV part supplier "ShopJimmy" and they sell you parts based on the symptoms, and he said definitely a T-CON board.  $25 later I had a fully functioning TV.  Since it was bigger than my tube TV, it became the main TV.

Though mine didn't have problems with it not turning on like Dave did, so who knows.

It does give me an idea though, how about a video of Dave taking the TV to a TV repair shop and doing a tour and video them doing some troubleshooting? Might make for an interesting video.

[M0BSW]

Those spring loaded thin probe tips make it look so easy.

Just saw Dave jump back while measuring something... After that he went under the bench to take powercord out?
Looks like there was near electrocution situation. Good thing nothing happened! 

Did you forget to discharge the mains filter cap? Thats why you added safety note about one hand behind back? 
I think it was before you were measuring the ESR on the live stream.

I saw that to,could it have been the revenge of that bloody hammer , seriously  switch mode capacitors those buggers hold some serious voltage, and I didn't see him use a bleeder resistor on that big one, maybe he did off camera,easily done though, hasn't the fluke 115 or 117 got a capacitor discharge on it,I seem to remember they had .

[EEVblog]

Did I just see Dave with his bag packed (with camera) and his Mum's TV underarm give a triumphant  to the webcam on his way out? Time 13:45. Obviously has priorities right. Deliver TV to Mum and then upload video.

I was wondering if anyone saw that...
Yes, fixed in the nick of time, had to pick my mum up and she wanted her TV working again! Footage is at the lab, so no video tonight.

[M0BSW]

Did I just see Dave with his bag packed (with camera) and his Mum's TV underarm give a triumphant  to the webcam on his way out? Time 13:45. Obviously has priorities right. Deliver TV to Mum and then upload video.

I was wondering if anyone saw that...
Yes, fixed in the nick of time, had to pick my mum up and she wanted her TV working again! Footage is at the lab, so no video tonight.

what was the fault in the end,looking forward to the video, to add to my experience in fault finding.

[FreeThinker]

Enjoy that lamington  .

[M0BSW]

Ah Yes , I see you fixed your Mums TV then Dave

[Jörg from Germany]

Hey Dave,

i have an idea, what is wrong with your LCD TV. If the caps are good dimensioned, the first thing which fails are the ccfl. They are burnd out. The inverter has to rise the voltage for the ccfls more and more, and then, if the voltage is too high, the inverter interfer all the digital and dsp stuff. I'm not sure why this happens, because i don't know, how the inverter controlls the voltage, perhapps it changes the switching frequency or duty cycle or what ever.

To check, if this is the case, you only have to stick out all ccfls, and run the "sucker". You need a bright light, to see, if the LCD shows something.

Would be interested, if this is the problem.

Greetings
Jörg

[synapsis]

Did I just see Dave with his bag packed (with camera) and his Mum's TV underarm give a triumphant  to the webcam on his way out? Time 13:45. Obviously has priorities right. Deliver TV to Mum and then upload video.

I was wondering if anyone saw that...
Yes, fixed in the nick of time, had to pick my mum up and she wanted her TV working again! Footage is at the lab, so no video tonight.

So Dave's doing cliffhangers now?

"Next week on EEVBlog: What was wrong with the TV and who shot JR?"

[Stonent]

Did I just see Dave with his bag packed (with camera) and his Mum's TV underarm give a triumphant  to the webcam on his way out? Time 13:45. Obviously has priorities right. Deliver TV to Mum and then upload video.

I was wondering if anyone saw that...
Yes, fixed in the nick of time, had to pick my mum up and she wanted her TV working again! Footage is at the lab, so no video tonight.

So Dave's doing cliffhangers now?

"Next week on EEVBlog: What was wrong with the TV and who shot JR?"

And in the end, it will all just be a dream.

[notsob]

METAL watch band on arm whilst over 240V - BIG NO NO Dave

[tom66]

i have an idea, what is wrong with your LCD TV. If the caps are good dimensioned, the first thing which fails are the ccfl. They are burnd out. The inverter has to rise the voltage for the ccfls more and more, and then, if the voltage is too high, the inverter interfer all the digital and dsp stuff. I'm not sure why this happens, because i don't know, how the inverter controlls the voltage, perhapps it changes the switching frequency or duty cycle or what ever.

Inverters don't compensate for ageing CCFLs, unfortunately. They are constant-current sine wave drive, with a small range of acceptable voltage which allows for some drift, especially from bulb to bulb. Modulation of bulb current is done by duty-cycle modulation of the high frequency drive current,  but the modulation is only there to maintain the bulb current. A bulb at EOL would simply light for a few seconds then extinguish as the over-voltage or over-current protection mechanism engages,

[Jörg from Germany]

Of course, You are right, it will be a current control.
Normally in the case of EOL of CCFL, the bulb would flicker at the beginning when the bulb is cold, like you wrote.
Now i also read, that Dave fixed it, so it seems to be an other problem.

But how ever, in my experience, a bulb working at EOL can cause several failures.

[elektron]

watcher's activities list on eevblog:

- watch a guy scrapping the basement for old electronics
- watch the same guy walking at electronics fairs and ... do nothing
- see non sense - "repair" videos  (i can't remember of any video of him actually repairing anything)
- see fotographs from postcards packed together with adaptor boards.
- see how you mount a camera on a bench
- learn to solder ?

not to mention, the hidden advertisements, emotional catches from showing his child (using the child for this purpose dave is inqualificable) ... you add to the list.

best to all.
peace.

[Legit-Design]

watcher's activities list on eevblog:

- watch a guy scrapping the basement for old electronics
- watch the same guy walking at electronics fairs and ... do nothing
- see non sense - "repair" videos  (i can't remember of any video of him actually repairing anything)
- see fotographs from postcards packed together with adaptor boards.
- see how you mount a camera on a bench
- learn to solder ?

not to mention, the hidden advertisements, emotional catches from showing his child (using the child for this purpose dave is inqualificable) ... you add to the list.

best to all.
peace.

You forgot honesty, Dave always says everything exactly like it. One time he was so honest it made me laugh. I don't think Dave would have career as politician.

[tom66]

Of course, You are right, it will be a current control.
Normally in the case of EOL of CCFL, the bulb would flicker at the beginning when the bulb is cold, like you wrote.
Now i also read, that Dave fixed it, so it seems to be an other problem.

But how ever, in my experience, a bulb working at EOL can cause several failures.

Most LCD TV inverters I've found will simply cut out after a couple of seconds and this is a latching error which will only disappear after power is removed again.

[brabus]

watcher's activities list on eevblog:

- watch a guy scrapping the basement for old electronics
- watch the same guy walking at electronics fairs and ... do nothing
- see non sense - "repair" videos  (i can't remember of any video of him actually repairing anything)
- see fotographs from postcards packed together with adaptor boards.
- see how you mount a camera on a bench
- learn to solder ?

not to mention, the hidden advertisements, emotional catches from showing his child (using the child for this purpose dave is inqualificable) ... you add to the list.

best to all.
peace.

What are you offering on your channel? Do you have one? Let's make a comparison.

Or maybe jealousy is just a bad beast.

Peace! 

[elektron]

What are you offering on your channel? Do you have one?

nothing really and no, i dont have a channel and that's because i'm not the one selling concepts around.
if we were to compare something, let's compare similar blogs across the spectrum.

your pick.. let's start with 3 proposals and rank them on (negociable) criterias:

- electronic insight offered
- degree of time "loosing"
- actuality and news
- [add more]

don't know which other criteria fits in, but eevblog fails the most and wins the "nerd entertainment" section.

any other criteria you might find usefull. please add. excuse my english. i'm not a native speaker.