Samsung LCD model LE40B86 - no colour

[PowerAmpFreak]

Hello!
Got in one of those with standard secondary caps failure. Replaced the caps and the smps works good. But the screen shows only black and white video - except for the MENU and OSD, these are all colour.
The colour adjustment is near maximum, so could this be a mainboard failure?
Everything's great except for only black and white video.

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

yes, I understand. This is quite fuzzy. How on earth could only the colour level be affected when everything else seems normal?
I agree, this one is weird. The blue screen during "no video" is blue aswell, so the set has the ability to display colour. Menu and OSD information is all in colour aswell. Just the picture information is black and white, oh well.

[PlainBill]

Re: Samsung LCD model LE40B86 - no colour

Does this occur on all inputs, or only one?

PlainBill

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

Nice to hear your "voice" again, Bill.
Well, the failure occours on both scart inputs and the RCA based video input aswell. Haven't had the chance to try the HDMI and VGA input though.
When pressing the INFO button on the remote, the tv reports "Shop mode". Could this be the problem? Perhaps they don't want that customers in the shop to play around with the colour settings?

[PlainBill]

Re: Samsung LCD model LE40B86 - no colour

Nice to hear your "voice" again, Bill.
Well, the failure occours on both scart inputs and the RCA based video input aswell. Haven't had the chance to try the HDMI and VGA input though.
When pressing the INFO button on the remote, the tv reports "Shop mode". Could this be the problem? Perhaps they don't want that customers in the shop to play around with the colour settings?

That would be my idea. Customers (and salespeople!!) have a way of setting outlandish combinations of color and tint. The HDMI input would be informative - it's a strictly digital input, no conversion from analog to digital involved. But first I'd try taking the TV out of shop mode.

PlainBill

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

According to Samsung website the shop mode forces the picture settings to default after a while, in order to reset the picture settings after customer's tweaking. Doesn't say anything about black and white picture though.
The website also tells how to get out of shop mode, first thing tomorrow.

[Wizard]

Re: Samsung LCD model LE40B86 - no colour

Demo mode resets to defaults on customers' settings.

What capacitors you were using to replace bloated ones? These still matched the faults I heard of with bad capacitors. Yours might be not right type of capacitors.

Cheers, Wizard

[Scenic]

Re: Samsung LCD model LE40B86 - no colour

also poke around for a service menu.
i've had a LCD monitor once that had a relatively strong green tint in the picture, but the OSD was fine.
turned out the green gain in the service menu was off (too high) for some reason.. back to default and everything was fine again..

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

Demo mode resets to defaults on customers' settings.

What capacitors you were using to replace bloated ones? These still matched the faults I heard of with bad capacitors. Yours might be not right type of capacitors.

Cheers, Wizard

Hello Wizard!
I use Panasonic FC and FM low ESR types. These have done the work in several Samsung's before. All picture adjustments make difference without the colour adjustment - this doesn't affect the picture AT ALL from 0-100%.

How do I get into the service menu?

By the way - I accidently wrote the wrong TV model in this thred, the correct model should be: LE40S86BD

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

Found the SM at Elektrotanya, which in detail describe the service menu.
I have two other Samsung's 40" LCD which failed seriously after capacitor damage. I traced the failures to the main boards on both units. Wonder if the high ripple content, resulting from bad caps, may damage the main board or perhaps is messing up memory locations. Is this possible to restore by the service menu? The problem is that the screen will never come up (the backlight does) so it's impossible to do anything in the service menu.

[mbates14]

Re: Samsung LCD model LE40B86 - no colour

Found the SM at Elektrotanya, which in detail describe the service menu.
I have two other Samsung's 40" LCD which failed seriously after capacitor damage. I traced the failures to the main boards on both units. Wonder if the high ripple content, resulting from bad caps, may damage the main board or perhaps is messing up memory locations. Is this possible to restore by the service menu? The problem is that the screen will never come up (the backlight does) so it's impossible to do anything in the service menu.

yup. its called glitching.

if a power spike occurs during an eeprom write, it can distort the value and location of where its being written, and WHAT is being written.

Glitches also affect CPU core execution as well, causing instructions to be interpreted as something they are not. (dont ask me how i know this)

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

This is what I believe may happened, yes. The question is if it's possible to restore this by means of the service menu. I wish it could include a factory-reset mode to restore all memory locations to what it was in prior shipping from the factory.

[Scenic]

Re: Samsung LCD model LE40B86 - no colour

service mode for a bunch of samsungs (including yours.. i hope.. )

[PowerAmpFreak]

Re: Samsung LCD model LE40B86 - no colour

Thanks, Scenic, I already have this in the service manual (but that you couldn't know!) - the problem is that I have two other Samsung LCD's where I suspect memory curruption occoured after psu cap failure. These two units I cannot even get a screen to poke around in the service menu. The backlights turn on for a second, then appears to restart and go through the startup routine once again, turn on the backlight for a second, then repeats...
Directly after cap replacement on one of the units I actually got it up and running for an hour or so, then suddenly turned itself off. I occasionally could get it up again, but it took several tries. Then finally it refuse to give any picture and will just restart like told above.
Probably those mainboards need to be programmed by external equipment (which I don't have) to bring back life.
My dream would be to find a jumper to short during power-up, to force the unit into factory reset, but the service manual doesn't cover this, so it might not be possible, just a wet dream...