EEVblog #446 - Dumpster Diving Samsung Plasma TV

[nitro2k01]

[David_AVD]

Could the "non working" PC input be due to it not supporting the screen resolution you fed from the laptop?

[Rodville]

I said this in the YouTube comments but I still think it could be a broken solder joint or even a loose plug.

I had a loose plug on a monitor that was dropped. I just reseated all the plugs and it worked again. And as a reminder to me if not everyone else don't let your 4yo carry it for you no matter how much she screams.


Sent from my Nokia 6185 using Tapatalk.

[kfitch42]

Could the "non working" PC input be due to it not supporting the screen resolution you fed from the laptop?

Doubt it. He mentions trying some other inputs @8:25, component and s-video. S-video at least should be immune to resolution issues.

So we are looking at a fault that effects VGA, s-video, and component; but not over-the-air analog. My gut says that one of those custom chips takes in all the external inputs and outputs them in some format usable by the rest of the system. probably that chip, or something in its output path has failed.

[Goophy629]

How can I have that company build a garbage room here? 

just looking for a big screen here..

[JoannaK]

How can I have that company build a garbage room here? 

just looking for a big screen here..

I know the feeling.. This Main PC of mine is 2008 wintage, and was not high end even back then, I'm sure many companies dump a lot newer Equip than this.

[Rufus]

One of those sold recently on ebay au for just under $200 pick up only.


edit: meant $ typed £ - fixed.

[Orpheus]

eBay AU prices in £ and not AUD?

[daveshah]

I wonder what would happen if Dave tried the HDMI input - maybe some analog circuit is broken? Also, could the 'Blue Screen' option interfere with anything?

[M0BSW]

 Don't let this go Dave fix it, it would be a nice unit on the lab wall or in your home, if she who must be obeyed without question, allows it.
going to keep coming back to see how your getting on with it.

[AndyC_772]

Even if the various video inputs don't work, I think there's a clue that you got plausible video snow from the RF modulator, as if perhaps the tuner is still able to connect through to the processing and display circuits.

Do you have a compatible RF signal available to test it with?

Maybe there's a service manual which gives a block diagram; the tuner might not go via some piece of circuitry that the other inputs have to?

[LaurenceW]

Yeah, but 380 watts?? There goes the planet

[hammil]

Aah! I was almost shouting at the screen...

Turn off the Blue Screen mode!!

[ecat]

Yeah, but 380 watts?? There goes the planet

Meh.

That's only when showing a full white screen at full intensity... maybe. I did measure my old plasma once, rated at 320W but iirc it was closer to 100W in normal use.

[tom66]

Plasma is an energy sucking beast. I got a 46" 1080p Panasonic for £70 on eBay as faulty, it was just a loose cable. It pulls around 350~400W on average TV (around 100~150W on darker scenes) and exceeds the rated 470W on certain scenes -- for example a high contrast noise pattern uses about 630W!! A 1080p display uses a lot more than a 720p display, due to the larger surface area to volume ratio of the pixels (more pixel wall to absorb light, less efficient cell.)

However, overall, the reliability seems to be around that of an LCD TV.  And the panels themselves are more reliable than LCD panels though vertical line failures are more common (which aren't repairable.)

Dave, here is something to try. You will need to source a Samsung remote which operates the TV -- however, one for a VCR, DVD player or another LCD will work too.

Turn TV into standby.
Press Info, Menu, Mute, Power.
Access service menu and perform a service reset.
(If that does not work try Mute, 1, 8, 2, Power for some sets.)

This fixes a lot of problems with Samsung TVs.
I encounter more Samsung than any other brand in my repair adventures -- "Friends don't let friends buy Samsung."

[ddavidebor]

yeeaaa dave nice dumpster diving!

i agree with tom66... you can do a hard reset of the television... samsung tv are all bugged... i've one!

[SeanB]

I buy Samsung Airconditioners.............. Some make it out of the compressor warranty.

[Fezder]

nice video, newer knew plasma's are such heavy & power hungry :S......but, looks good form inside, what i understand .

[tom66]

Panasonic make far better plasma sets. The one I got is full of Rubycon . (Strangely, only a few Panasonic caps in it...  ) And much nicer overall construction -- only a couple of 'lytics on the main board (not like the Samsung one -- seems like the engineer may have had shares in electrolytic cap manufacturers?!)

[JackOfVA]

If/when Dave gets the plasma TV working, please take a look at the RF noise radiated by the set - spectrum analyzer and a loop probe or even just a wire stub made by cutting back the braid and jacket on a length of coaxial cable.

In the amateur radio world, plasma TV sets are notorious for radiated interference - so strong that they may be heard a km or so distant in the worst case and easily 300 or  400 meters. From what I've been told, worst signals are in the 3.5-4 MHz band, but unwanted artifacts exist up to 30 MHz or more. 

LCD sets are much quieter, so that (a) plasma TVs fail frequently and (b) are becoming obsolete are both good things for us radio amateur operators.

[tec5c]

The blue screen mode will not effect any of the inputs. The purpose of blue screen mode is actually accidentally demonstrated in the video; When no/poor signal is being received, the unit will display the blue screen as opposed to the "snow" or noise.
The fact that it powered up into TV mode means it was last used in this way as TV's have what's called power return. It seems unlikely that the inputs have failed although it is not unheard of.
Dave, I have a few Samsung main boards from when I did my apprenticeship in "brown good repairs" (Old school trade name for Tv repair) laying around at my parents place.
If you haven't got the unit working soon and we are still set to look at that old HP RF test gear then I'd be happy to see what boards I've got to replace it or fault find the dud.
Catch up with you soon.

P.S Plasmas are banned in some countries due to excessive power consumption.

Jason (Thales)

[topbood]

I hope this isn't considered cheating, but here is the service manual.
http://rapidshare.com/files/1261898320/samsung_ps42s5hx_xex_d72a_sm.pdf

I'd try composite video or s-video. They seem to take a different path to the Scaler. (pg. 23)

[ecat]

The old plasma I mentioned in post #13 was 36" with a wacky 840×480 resolution. I just tested my 55" HD, on subdued indoor scene it pulled around 200W, a bright snowy landscape pushed it to around 450W , so average viewing is probably between 250 - 350W.

Still, living in Scotland, it's better to think of it as a useful source of background heating, useful for 8 months of the year at least

Edit:
Some of these TVs have a 'hotel mode' that is selected in the configuration. I think this mode allows the owner to restrict the number and type of working inputs so TV only for example would prevent users from viewing any video source other than TV.

[tom66]

They pump square waves at 200kHz with around +/-100A current on the rising/falling edges (light emission), so they do produce a tad bit of EMI. Hence the heavy metal shielding. The EMI shouldn't exceed rated limits (i.e. no worse than a rated SMPS etc -- it's not as if there are exceptions for plasmas.) Older models were much worse but the newer ones are about the same as an LCD TV.

The technology is pretty fascinating to study. High power usage so lots of power semiconductors. Dave's one there is an older Samsung using hybrid modules, i.e. all semis on one chip, so you're not going to see much exciting there. The newer ones do use discretes. The panel itself is actually a kind of memory module. The image is loaded into it by the column and y-drivers, then the scan sustain and common sustain drivers (the left and right boards) make the image appear. Each sustain pulse makes the written cells emit light. High contrast is possible, and motion performance is good too.

P.S Plasmas are banned in some countries due to excessive power consumption.

More like severely restricted... they still exist but the brightness is turned way down to keep power usage low. First thing I would do is go into the service mode and set it to make it think it's in the US or another country... boom goes up the brightness. I love saving energy but I don't like LED TVs one bit. Holding out for OLED or FED/SED. (One Canon SED prototype used only 14W for a fully bright scene 400cd/m^2, damn impressive, sadly, it looks like the technology has been all but abandoned.  )

[ecat]

Holding out for OLED or FED/SED.

 

I'm not a fan of LCDs