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Equipment Repairs => PLASMA TV forum => Topic started by: Turnip on May 31, 2018,12:24:25

Title: Samsung P50C450B1W - S/by issue.
Post by: Turnip on May 31, 2018,12:24:25
Hi Folks,

Have one where on turn on get the Sammy Fa-Da where voltages rise to normal, then set reverts to S/by. Thought check for dries on the P/S and resoldered here and there.

No obvious shorts - Wonder if anyone has ideas - Thanks - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 01, 2018,03:46:28

Hi Chris,

Unplug the lead from PSU to Y-Main (Y-Sus). Turn it on and see if it stays on. If yes, then reconnect and unplug the lead from Y-Main to X-Main (Z-Sus). Turn it on and see if it stays on. If yes, then X-Main is faulty.

LED on Logic Board normally blinks once per second. If not possibly Main Board. Could also isolate the PSU and force it on and see if any of the LT rails fire up to prove the PSU is working. You won't get Vs as this is switched on by the Logic Board. PS-ON is 0V so you'll need to ground PS-ON to activate the power supply.

I'll upload the fast track guide for the Trump model if the forum accepts the file format.                                Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 01, 2018,11:30:51
Hi Bruce,

Thanks for the 'Heads Up' Always thought Sammy issues were dries on the P/S as done a few. Note 'Trump' accepted on Quuq, so will check it out.

Gather he's over here in the UK soon to play golf, maybe with our Queen or Prince Phil - After he's sorted long divided countries, China exports and EU imports, giving Russia a quick slap on the way.

Seems quite a chap in his own estimation - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 02, 2018,06:11:47
Hi Bruce,

Did as suggested, then with the plugs in Vs / Va / Vsc / Ve were correct 'till the logic board turned Vs off. Led on logic flashes every three to four seconds - Don't know if it's significant. Low voltages on P/S are correct all the time, so guess logic senses an error somewhere - Bit complex, any more thoughts ? - Thanks - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 02, 2018,16:34:17

Hi Chris,

I note that the fast track guide mentions that the set will turn off if Y or X main is unplugged. Could well be the main board - see if you can generate test patterns as per attachment. If so, then main is the culprit.

Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 03, 2018,12:21:36
Thanks Bruce, will do.

Notice the logic board doesn't shut down the P/S, just the Vs. with PS low voltages still OK.

Chum mentioned that CS809 (68n/1250) can go O/C (top centre power board) and CS401 (Small Blue ceramic under heat sink RHS) on Y-Sus can go S/C - Not my problem though, but might be useful - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 04, 2018,05:49:11

Hi Chris,

Yep, Main activates PSU via PS-ON and logic board activates Vs via VS-ON. Were you able to get test patterns going?

My gut feeling is that the main board is at fault, given that the Logic board LED is giving wrong code.                    Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 04, 2018,12:02:59
Thanks Bruce,

Didn't realise the logic board Led had a code as suspected a flash every three seconds might be normal.

Note that on Ebay, every panel for this set is really cheap, except screen, speakers, stand screws, mains lead and the genuine RCU.

Have ruled out speakers and RCU. screen seems pretty well OK, so think go for the SSB as first option - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 11, 2018,09:58:54
Hi Bruce,

Forgot to mention tried the Test Pattern biz, but as Vs from logic shuts down (3v to zero) in a couple of seconds (other P/S
voltages OK) don't get any display.

Guess logic checks for error most everywhere, seems most errors don't knock off Vs judging from pictures on the 'fast track'

Out of interest, if screen damaged (Looks OK) would logic cut the Vs, as suspect air in the panel would prevent operation ?

Many thanks - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 12, 2018,04:02:19

Hi Chris,

In my experience, a cracked panel always takes out the buffer boards, and possibly the Y-main. Are you able to try the TV with the buffers removed from the Y-main.

Another thought, since a lot of error signals from scan circuits are routed via the logic board to the main, why not try removing the flex that goes from Y-main to logic, and see if the LED on the logic returns to 1 blink per second. May indicate a faulty Y-main.

Could try forcing Vs on but will likely create more mayhem than currently exists. I hate these sort of faults where only solution sometimes is to keep throwing replacement boards at the unit. See how you go.

Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 12, 2018,11:07:18
Hi Bruce, thanks a lot.

Cust has donated the set, but naturally without the stand as such folks throw 'em away where they turn up on Ebay for 50 Quid or so. Chap not dismayed as didn't want to spend anything much. Offered him my nice 50 inch Pana where the Ysus IGBTs had gone pop due to earthing issues, but 100 was a bridge to far, even with the stand, and rather newer than his Sammy.

Will check your suggestions, as hate dump a decent set. Also plasma stack nicely against the workshop wall, taking little space.
Just got a cheap stand for a 60 inch LG with a Y-sus IGBT issue - Just have to mend it - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 16, 2018,11:25:13
Hi Bruce,

Did as you suggested, where disconnecting flexy Y-sus to Logic gave me a one second logic Led flash - Hopeful. Tried without the buffers with flexy in - 3 second flash so guess a Y-sus issue.

To Ebay where most every board is incredibly cheap - Working Y-sus for under a tenner inc post - Guess there are a lot about, as seems no one tries mend sets these days - Thanks again - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 18, 2018,05:16:15

Hi Chris,

That's sounding hopeful. I always encourage punters to have plasmas repaired, more for selfish reasons than anything else. They do give a glorious picture. Sourcing the boards is the biggest hurdle and I don't always have a win.
Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 19, 2018,11:01:24
Hi Bruce,

Got 'screen smash' Y-sus board 8.50 inc post. PS clicked, squawked then turned itself off. Checked Vs to deck - S/C. Price is pretty normal over here, so there must be good ones about as there's dozens of 'em on Ebay.

Needed a screen, so to a supplier who had one from a 'screen smash set' - Queried, where he said it was a typo, and send me a really nice screen for a small Lap-Top where I wanted LTA216AT01 where kids had knocked it over then poured sugar loaded juice over it causing almost perfect circular patches here and there - Still looking. Tried a presumed equivalent where it fitted perfectly but the picture looked a bit odd, bit like an Eeprom issue with sets which don't have the famed duff chips on the T/con. Guess swapping stuff has issues, can't win 'em all - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 20, 2018,03:35:33

Hi Chris,

A smashed screen will never do if (A) it was smashed while the set was running or (B) the set was turned on after it was smashed.

It's a tough life.                                   Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 21, 2018,12:58:46
Well said,

But selling folks always say 'Its from a smashed screen' even if buying a screen. Note you mentioned that a smashed screen always duffs up the Y-sus and the buffers.

Supplying folks are sending another Y-sus, not needing the old one back, and all for 8.50 inc post.

Pretty decent considering. Guess they shouldn't try sell a Y-sus as OK if they can't check it, but they do as there are rather a lot about - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 24, 2018,10:38:33
Hi Bruce,

Thought mention the new Y/sus doesn't seem to have S/C IGBTs but the Vs dies after 2 seconds and the logic Led shows the three second flash as it did with the original board. Seems I'm back to the start but not too much out of pocket.

Wouldn't mind advice. Seems as a broken screen duffs up the Y/sus and buffers, maybe my issue is elsewhere. Sadly as the screen doesn't light up, though the sound gives the usual Sammy Fa-Da, haven't a clue what to check next.

Tend to think LCD sets have a future, even curved ones - Noticed a big one at the local tip today, in the pile for smashed screens where you might think a curved screen would survive a brick - Thanks for any thoughts - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 26, 2018,03:14:19

Hi Chris,


Since you have been unable to generate "Power and Logic boards test patterns without the Main board" as per fast-track guide, you

may have a faulty logic board. (remember to force the PSU on for this test). Can't say I recall ever replacing a Logic board, but I

guess it is the T-Con of the plasma world, and have replaced LCD T-Cons to be sure.

Checking logic boards is not a precise art. It needs 5V from the PSU and probably has some series regulators on it. Sure-fire test is

by replacement of course. This may not be a definitive solution but I'm running out of ideas.


Bruce



Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on June 26, 2018,12:26:43
Many thanks Bruce,

Folks have said a duff screen will cause the issue, so had a good look and mine seems OK, far as I can see. Most all boards for this set are incredibly cheap for some reasons, so suspect something lurking that selling folks don't care to speak about.

Guess go for a 'Logic' then maybe bin it.

Was almost getting to like plasma after Y-sus fun with recent Panasonic sets - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on June 27, 2018,06:22:42

Holding my breath, Chris. Don't give up on plasmas - they're just another tv, albeit a bit different to other TV formats.

Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on July 13, 2018,11:46:11
Hi Bruce,

Breath again, as tried a logic board and still get a three second flash.

Tend to suspect it's the screen although it looks OK.

Don't suspect there's a way of checking a screen, sort of firing it up with batteries ?

Thought not, so guess wait for the next one though Sammy plasma are rare, though get heaps of Panasonic plasma where overnight updates cause folks to feel Panasonic isn't the biz.

Such folks pull the plug at night after following Pana advice, but sets just flash Red in the morning.

Seems odd, as when S/by and CH+ are pressed together, set works normally with updates and new channels still turned off.

Glad I don't now do house calls as seems a once a month biz - Chris.





Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on July 14, 2018,03:46:57

Hi Chris,

That's a sad finale, then. Best check a panel for cracks in bright sunlight and examine it in a slight diagonal angle, otherwise they're hard to pick up.

I killed 2 Y-Sus boards on a TV once, until I noted the crack in the panel. Plenty of Panasonics indeed. Trouble is obtaining boards for them.


Bruce
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: Turnip on July 15, 2018,12:30:48
Thanks Bruce,

Gather you don't have the issue where certain Panasonic sets - Plasma and LCD - Notice an overnight update then refuse to function 'till you press S-by and channel up together, do a factory reset then turn off possible updates.

Suspect the download wasn't intended for those models, but some sets listened in and obeyed. Bit of an earner but some have been back three times, as old folks don't listen and don't turn off overnight.

Worst seems to have been the Pana TX-P50G20B which is otherwise a nifty set, as we had one back three times, as cust said it used to click in the night, even though he was supposed to turn it off.

Customers always being right, trying find something cheap and cheerful - Loaned him a Vestel LCD 40 inch and he loved it, even though heat had caused the diffuser sheets to melt a bit at the top

Amazed that he couldn't tell a Panasonic plasma from a Vestel LCD - Gratified though - Chris.
Title: Re: Samsung P50C450B1W - S/by issue.
Post by: downunder on July 17, 2018,05:13:05

Hi Chris,

Never had issues with sets being disabled, but we have had sets that are nocturnal, switching themselves in the wee hours of the morning, notably Samsungs and LGs, giving customers the heebyjeebies. Did have some probs with some of the early sets when punters selected the Community Channel (which had progressed to mpeg4).

These sets would freeze and had to be reinitialised to restore them. But don't recall Panasonics being in this mix. Suspect the EPG providers have been tinkering with their formats.
 
Bruce