Samsung PS-42V4S Shuts down after like 35min

[Hagis2k]

Hi everybody i seached the forum here to see if i could find a similar fault
the plasma tv works perfect for like 30min then it starts to flicker...

Look at this video, then you can clearly see whats going on is this typical
a buffer problem or psu, am about to buy an esr meter

http://www.youtube.com/watch?v=_a-PKquiQoc

And the model name is just "PS-42V4S" with no extra /xxxxx model number its sold in sweden

Will open it up tomorrow and take some quality pics of it and the pcb's

[PlainBill]

Re: Samsung PS-42V4S Shuts down after like 35min

Does this occur on all inputs, or only one?

PlainBill

[Hagis2k]

Re: Samsung PS-42V4S Shuts down after like 35min

Yes i assume so, im testing the cable atm i will update it with status asap can't get dvi to work strangely is it dvi-i like analouge in i think i read something about a firmware issue too on these sets...

[Hagis2k]

Re: Samsung PS-42V4S Shuts down after like 35min

Works on antenna (on over an hour), shall try component and scart again seems not to work at all on dvi-d

[PlainBill]

Re: Samsung PS-42V4S Shuts down after like 35min

Sorry if I was being obscure; that problem looks like a failing regulator in the analog circuitry. My bad, I was going to ask if you had the same problem with the menus.

PlainBill

[Hagis2k]

Re: Samsung PS-42V4S Shuts down after like 35min

Seems like i can keep it up running on "antenna/tv" input forever without problems so something must be wrong with the video processing.

Shall try today today to keep it running on antenna, and then switch source to scart or component video, to me it feels like it loses the sync of the video source...

[PlainBill]

Re: Samsung PS-42V4S Shuts down after like 35min

Seems like i can keep it up running on "antenna/tv" input forever without problems so something must be wrong with the video processing.

Shall try today today to keep it running on antenna, and then switch source to scart or component video, to me it feels like it loses the sync of the video source...

Roughly correct. The processing is usually done on a single board - I believe Samsung refers to it as the 'Main Control Board'. Checking the voltage regulators on the board would be the first step. If they are good, replacing the entire board is the usual solution.

PlainBill

[Hagis2k]

Re: Samsung PS-42V4S Shuts down after like 35min

I think that is an wise idea, seems like the error can differ a bit today i could have the set up and running without issues, until i could see some ghosting text moving on the screen shall be interesting to measure the capacitors with the newly ordered atlas esr70 meter
it works flawless when it is cold so some heat related i say...

Will look for a used working main control board then, if i do not find something wrong with the voltage regulators...

[PowerAmpFreak]

Re: Samsung PS-42V4S Shuts down after like 35min

Is the mainboard perhaps "BN41-00254 C" ?
I also had problems with a PS-42V4S, not the same as you though, my problem was vertical lines directly from start. The thing is that all OSD and MENUS worked all the time, so the failure was in the mainboard. It was hard to find a used mainboard, if memory serves me right. A good 6 months later I powered it up again, just to see, and the fault was gone. Obviously some "bad dog" is lying in the mainboard...
It stands in my workshop, don't know what to do with it.
I might start to consider that everything is not repairable, I'm too dumb to have electronics "almost working" put in the garbage

[PlainBill]

Re: Samsung PS-42V4S Shuts down after like 35min

Is the mainboard perhaps "BN41-00254 C" ?
I also had problems with a PS-42V4S, not the same as you though, my problem was vertical lines directly from start. The thing is that all OSD and MENUS worked all the time, so the failure was in the mainboard. It was hard to find a used mainboard, if memory serves me right. A good 6 months later I powered it up again, just to see, and the fault was gone. Obviously some "bad dog" is lying in the mainboard...
It stands in my workshop, don't know what to do with it.
I might start to consider that everything is not repairable, I'm too dumb to have electronics "almost working" put in the garbage

When I worked in the test department of an electronics manufacturer, one stated philosophy was 'Given enough time and parts, we can fix anything.' Left unsaid was the fact that sometimes the cost of repair exceeded the value of the item being repaired. (Those are called 'learning experiences'.)

PlainBill

[thelmores]

Re: Samsung PS-42V4S Shuts down after like 35min

If you are repairing your on TV..... and have the time, some tech savy, and lots of patience, you can sometimes repair things to component level. But in TV's, this "normally" limited to the power supply, because a lot of the other boards have lots of small surface mount components, makes it difficult, even for the best trained. Thus in most cases (other than power supply), probably best to isolate to one particular board, and replace that board.

In a business situation, you just don't have the luxury of spending several hours trying to repair a board that may cost $100-$150 dollars........

[mbates14]

Re: Samsung PS-42V4S Shuts down after like 35min

If you are repairing your on TV..... and have the time, some tech savy, and lots of patience, you can sometimes repair things to component level. But in TV's, this "normally" limited to the power supply, because a lot of the other boards have lots of small surface mount components, makes it difficult, even for the best trained. Thus in most cases (other than power supply), probably best to isolate to one particular board, and replace that board.

In a business situation, you just don't have the luxury of spending several hours trying to repair a board that may cost $100-$150 dollars........

No, its not that. not that at all. maybe in a few cases.

The "real" problem is the fact that you cannot get the certain discrete transistors or ICs that each board requires. Either because they are proprietary to the manufacturer, or they are just "unavailable" on this side of the sea... Unless you got 2nd hand back sources in china. sometimes you can get parts that way, even then you never know what you get. whether is bad second hand, or good second hand. This is a rebuilder/technicians worst nightmare, at least it is for me. There has been a few RARE cases that I had to re-engineer circuits to work around not being able to obtain certain transistors/basic ICs. And this effort sometimes fails, and sometimes works great. 50/50 shot.

Examples of being stuck in this paradigm would be custom ASICs or MCUs designed specifically for the manufacturers and datasheets/info/supplies are confidential. Maxim has done alot of this, MiTek does this, etc...

Another example would be off-the-shelf parts that have been "privatized" where datasheets and replacements are unavailable unless "leaked" (Vizio CPUs, etc..)

Then you got parts with privatized markings that mean nothing to anyone except the OEM licensee.. (AC Delco was BAD for this..)

At least, thats the way it is for me. SMD rework, and component level repair of the board was never a problem. its locating "unobtanium" parts, that IS....

A good example would be some of Hitachi power supply units used in certain plasmas, using proprietary MCUs that run the inner-workings of the power supply, panasonic has been known to do this as well.. Making troubleshooting very difficult, not to mention impossible when that IC is bad.