Samsung PN43E450A1F 43" Plasma - with "line offset"

[ngth82]

Hi everyone -

I picked up a Samsung Plasma model PN43E450A1F. The TV seems to be working fine when you initially power it up, but after 15min-1hr into watching, the display appears to have a couple of lines "offset" from where they should be.

This is most noticeable when viewing menu's. No caps appear to be bad, the factory test M-patterns appear to be fine when i initially power up the TV.

Vitals:
Panel: S43AX-TB01. Vs = 209V, Va = 58V, Vsc = -185V. All measured and within 1V. I'll adjust these to spot on values in a bit.
Y-buffer: 43EH_YB2_LAYER / LJ41-10138A
XY-Main: 43EH YM / LJ92-01854A
Logic: 43EH Logic Main / LJ92-01849A/B/C/D/E
SMPS: BN44-00508A / PSPF251501A
X-buffer: 43EH X-buffer (1-layer) / LJ92-01852A
Main: BN96-24583A


I'm not sure what the effect is usually called, other than the video has lines that are "offset". Also, the picture some times seems pixelated even though all the voltages are spot on.

I ran out of compressed air / freeze cans. I'll try to cool them down later this week to see if heat is a primary factor.

All of the cables have been re-seated. No change.

[freakaftr8]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Mainboard fault most likely.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Mainboard fault most likely.

Thanks for the tip! I’ve placed bids on a few items on eBay ...
I’ve been out in business travel for the past few days.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Update:

I picked up a PE51E450 the other day with a panel that sparkles red/green and is dark. The main board from the 51" look identical to the 43" unit that i'm discussing on this thread.

I found the service menu for the Samsung TV's --> power off; mute, [1], [8], [2], power on.
Looking around the option menus, it appears that i can change the TV type from 51EhhcD (on the 51") to 43EHHcD for the 43"

The base model is the same for both: PE450
The SVC model is the same for both as well: 450

Won't hurt to try right? The main boards look identical to each other.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Quick update: i guess i don't have to change the base model and SVC model information - that appears to just be the FW identification string on the TV.

The firmware for both the PE43E450 (target TV) and the PE51E450 (donor TV) are the same from Samsung since its grouped under the E4xx 2012 series plasma units.

https://www.samsung.com/us/support/o...tv-e4xx-series

The donor main board is in the target TV. Time to test it for the next few hours and see if that worked.


5 minutes into it: the lines are back. I'll try and swap out the logic board and all compatible boards from the donor tv.

-Thomas

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Re: Donor parts - no other parts from the 51" donor TV are compatible.

I think we are back to debugging with what i have. I returned both TV's back to stock. The line "separation" issue definitely occurs after the TV warms up. If you watch it carefully, it's almost as if you can watch the screen "shake" like a cheapo camera tripod while some of the horizontal lines are placed in the wrong spot.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Additional observations:

After ~30 minutes of the TV switching between lines /no lines, it settled down and is working fine again.

[tom66]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Well you clearly have an issue that is temperature dependent so get out a hair dryer or hot air gun set on low temp and start heating up bits until you find what causes the fault

You can also try test pattern generator by bridging pins 3 and 4 of the connector on the control board. If the fault is present on there then it would be a control board issue.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Thanks Tom66.

I've been running the built-in test pattern for a while now (until the unit shuts itself off) from shorting pins 3-4 on the logic board. No observable issues - albeit, the test patterns are solid colors or horizontal/vertical/diagonal scrolling. It looked okay.

However, the problem is definitely present with the main plugged in and the logic board running in normal mode.

Yep, i'll let the unit cool down first then look at it with a hair dryer for inducing the failure.

In my original post, i mentioned i'm out of compressed air /freezer cans. Would spraying the board during operation "fix" the issue? Maybe that'll be a more indicative way of pin-pointing the problem.

Thoughts?

Thanks!
-Thomas

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Is there any possibility that the logic board is actually bad? (vs. the main board, as suggested in post #2?)

[tom66]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

It may be possible to pinpoint the issue with a mix of freezer cans and hairdryer. Careful though, as the aerosol is flammable and could ignite on the hot heating element of your hairdryer.

It sounds more likely that it is a control board fault but it is also possible that the LVDS receiver portion of the controller chip is faulty for some reason, for instance a damaged crystal reference, bad voltage to the IC, defective chip/ESD damage...

That's why I think you need to try and locate the fault with heat.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Hi Tom -
I was able to find some time Sunday morning to dink around with the TV.

Looks like i'm able to alter the image output when i start heating up the area indicated by the red box in the attached image. I can get the image to look interlaced/offset by a few horizontal lines across the entire screen.

If i told on the "cold air" function of the hair dryer, it returns to normal. I can get this to occur quite easily and repeatably.

I've already removed and visually inspected both the y-buffer and the X/Y main board. No defects that i can tell in that area.

[tom66]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Interesting - that speaks to one of the logic buffer chips that buffers the signal to the scan driver being bad, or one of the scan driver ICs being bad (sometimes called "buffer ICs" although they do not buffer anything)

[freakaftr8]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

I agree the best thing to do would be to swap out the buffer board. But before you do that disconnect the buffer board from the Y sustain and check all connections

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Thanks for the input. That's what I'm thinking. The heating was localized (as much as possible) to the 3rd/4th buffer (yes, i call them buffer's too..) IC from the top. The hair dryer that i used has a "flat nozzle" attachment so the air was pushing out of the dryer like a wide rectangle instead of a full on circle. I did notice that the plasma screen heated up as well as the heat transferred over to the panel. I'll try and provide some insulation between the buffer board and the panel to make sure it's just the buffer IC(s).

If I can find a Y-Buffer for cheap, then it's worth while, even if there are no guarantees that's the exact issue. (Sub $25 is a good test investment i think)

The combined X/Y sustain appears to be fine (as far as i can tell). The Power rails on that thing look solid. Before I buy a different Y-buffer, I want to spend some time and scope out the power rails to see if they fluctuate under localized heating in the same spot... if they don't, then that builds some additional confidence in a bad scan IC.

I may have some time later this week. Work has been nuts lately. Stay tuned!

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

I jumped the gun and purchased a "new" (to-me) Y-buffer board from eBay @ $9.99 shipped. It'll arrive Friday/Saturday.

It's a $10 gamble in lieu of finding the time to debug this for the time being. Not the best approach, but I just don't have the time in the short term.

Stay tuned!

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Issue appears to be closed now.

The "new" (to-me) Y-buffer board arrived today. I installed it four hours ago. The TV has been working fine since.

I would agree with tom66 - one of the scan IC's on the original buffer board were temperature sensitive.

[ngth82]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Update: I sold the tv 2 weeks ago. It was working like a charm since replacing the Y-buffer board. Thread closed

[freakaftr8]

Re: Samsung PN43E450A1F 43" Plasma - with "line offset"

Good to know! Buffer ICs can fail in other ways besides shorted. Had one on a LG that was actually open. Caused a no picture but had prime.