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Old 05-21-2022, 10:50 AM   #1
Maalobs
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Default Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

My mother's Philips 70PUS7505/12 TV suddenly began to display this kind of behavior:





Contrast differences from a light area to a dark area above, become "echoed" vertically upwards.
It's the same behavior with all colors as long as there is a relative contrast difference between them.
There are no other issues; the backlight works fine, the Error code buffer is all zeros.

I tried it on each HDMI-input, the result was the same.
I tried in another resolution, still the same.
I tried with three different sources; tv-decoder, media player, laptop, no difference.
I tried fiddling all the picture-related controls on the TV, but nothing had an impact on the problem.

The back label says:
Code:
Model:      70PUS7505/12
Serial:     FZ3A2101052xxx
Set Option: 016
Chassis:    S TPN20.6E LA
The service manual is available here.
The troubleshooting flowchart in the service manual shows:

The flowchart suggests updating to the latest software when experiencing a picture-related issue which is non-intermittent.
There was an update available, so I installed that but the problem still persists without any difference.

Does anyone have an idea what kind of problem this is even?
Is it a known problem with this series of models?
Is there a service notice about it from Philips or something?

Thanks in advance!
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Old 05-21-2022, 12:01 PM   #2
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

first make sure your connections are secure and clean, ie tcon ribbon cables and lvds cable from mainboard to tcon, can clean with isoprophyl alcohol, some use a pencil eraser, not too vigorously they can be delicate, if no joy, something to try, may have to play with width and location of tape: https://www.youtube.com/watch?v=Jt4myvliNow

Last edited by nomoresonys; 05-21-2022 at 12:05 PM..
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Old 05-21-2022, 12:08 PM   #3
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

it could be a bad tcon, if the above doesn't work maybe heat up the tcon board with a hairdryer then try tv, see if there's any change.
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Old 05-21-2022, 01:35 PM   #4
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Thanks for the reply!

I contemplated something like that, but I was expecting the problem to be isolated to either half of the panel in that case.
It's consistent across the entire screen, and there is no "glitching" in the artefacting, it's completely static and only follows changes in the video source.
So the artefacting is completely still when the video is not moving, for example in menus.
But this type of problem in the T-CON can appear in this "static" way too, you say?

I remember reading a comment some time ago about what the tape-solution does, if I recall correctly it's a matter of feeding power simultaneously from both ends of (vertical?) lines across the entire panel to power the LEDs on those lines.
If there is a problem with the power output from one side in that it can't maintain the voltage or supply enough current, this affects the entire line with interference.
The tape is then used to mask away the power delivery from the detected bad side, so that the good side can supply power to the entire line without interference.
Is my understanding correct?

The T-CON board is not covered at all in the service manual.
The best there is, is a description of the CN408 connector between the SSB and T-CON on page 9-4-8, but there is nothing about the connectors from the T-CON to the panel, where I understand the tape has to be applied.
How do I find out which pins to mask on the connectors from the T-CON to the panel?

Is there something that can be done on the T-CON board?
For example is this type of problem originating from a voltage regulator issue, maybe it's a crappy capacitor that has drifted out of spec or something?

This TV is 70" and in my mom's apartment so getting it out of there and to my house is out of the question.
An on-site investigation is possible but it won't be easy.
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Old 05-21-2022, 02:35 PM   #5
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

there was a thread not long ago where Diah helped someone, somehow he knew exactly which signals to block, but I don't know, i usually try one end or the other.
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Old 05-21-2022, 02:38 PM   #6
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

had a similar problem with an old sanyo not long ago, seemed like tcon or panel problem, well It actually was panel related, it was one bad tab bond, shimmed it and got a good picture, was the usual tab, top right when looking from the front.
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Old 05-21-2022, 03:10 PM   #7
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Have you unplugged ribbon cables one at a time, and checked screen?
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Old 05-22-2022, 01:08 AM   #8
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

It is going to take a few days before I can go back there and mess around with the TV, so I'll collate all suggestions and work through the list when I am there at the TV.
  • First make sure your connections are secure and clean, ie tcon ribbon cables and lvds cable from mainboard to tcon, can clean with isoprophyl alcohol.
    Yes, I can definitely clean all the connectors.

  • May have to play with width and location of tape: https://www.youtube.com/watch?v=Jt4myvliNow
    I'd prefer not to experiment like that, surely there must be a way to identify which pins need to be masked off.

  • Heat up the tcon board with a hairdryer then try tv, see if there's any change.
    Look for heat-affected issues, OK.
    Maybe use freeze spray too I guess, to see what cold temperature does to it?

  • There was a thread not long ago where Diah helped someone, somehow he knew exactly which signals to block, but I don't know, i usually try one end or the other.
    It sounds so random, do you professional repairers really have to work like that with this type of issue?
    Surely the correct pins must be identifiable by measurement as a specific power rail or something, if the T-CON board lacks documentation?
    I have a decent multimeter and I guess I can lug along the Rigol scope if it's relevant to find ripple on DC levels or similar.

  • [...]similar problem with an old sanyo, it was one bad tab bond, shimmed it and got a good picture, was the usual tab, top right when looking from the front.
    By "bad tab bond", do you mean the flex cable connections from the panel to the long narrow PCB at the bottom edge of the TV?
    By "shimming", what do you mean, did you put something in there on the other side of the flex cable to apply force to the connection?

  • Have you unplugged ribbon cables one at a time, and checked screen?
    No, I haven't opened it, but I will unplug, clean and re-seat all ribbon cables one by one.
    I was by my mom to fix an internet issue after the ISP got changed and she said "oh and while you're here, the TV picture looks wierd"
    I had the laptop with me and did everything I have described in the first post.

Anyways, I have in fact watched RepairAllTV videos before, and now I went back through his collection and looked for videos that covered this type of problem.
He has solved this type of problem in different ways.

As in the video that nomoresonys linked to, here are two other where he also fixes the issue by applying unexplained tape masking:
https://www.youtube.com/watch?v=XCJAx92JwPs&t=1010s
https://www.youtube.com/watch?v=vV3FCTAC1no&t=318s

Here the issue was a short-circuited capacitor on that long, thin PCB that I guess is part of the panel assembly:
https://www.youtube.com/watch?v=Ij3sReZjpAY&t=1031s

Here he uses a piece of thermal pad to put pressure on the flex cable connection that goes to the panel:
https://www.youtube.com/watch?v=ITHprEQhyL0&t=312s

Here (or actually in the part 2 video) he replaces the T-CON PCB:
https://www.youtube.com/watch?v=HT5akVxopmY&t=590s

I'm open to concrete suggestions.
I'll never hear the end of it if I go there and create chaos with that big TV in pieces and then don't end up fixing it.
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Old 05-22-2022, 02:15 AM   #9
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

why you don't use the guarantee right and contact Philips since this model 2020 series..!!
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Old 05-22-2022, 04:56 AM   #10
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Done

Last edited by nomoresonys; 05-22-2022 at 05:56 AM..
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Old 05-22-2022, 06:35 AM   #11
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Quote:
Originally Posted by Diah View Post
why you don't use the guarantee right and contact Philips since this model 2020 series..!!
+10, if under warranty or guarantee it should go back.
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Old 05-22-2022, 06:43 AM   #12
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

"Here he uses a piece of thermal pad to put pressure on the flex cable connection that goes to the panel:
https://www.youtube.com/watch?v=ITHprEQhyL0&t=312s" that IS it, it's called a tab bond and not as useful with the newer tvs that pretty much have NO frame holding them together.
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Old 05-22-2022, 06:50 AM   #13
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

this one dives deeper: https://www.youtube.com/watch?v=pfrRhw7-ZII
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Old 05-22-2022, 06:54 AM   #14
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

what you need to understand is there are at least a few different issues that will make a tv display in that manner, if you can find someone that can tell you exactly what is wrong from a picture, I'd like them to help me pick some lottery numbers.
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Old 05-23-2022, 02:17 AM   #15
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Yes, this guy explains it to some extent in a two-part video:

I fixed a broken 4K 55 TV with TAPE | How to fix a TV with a blank screen
https://www.youtube.com/watch?v=pfrRhw7-ZII

Repair Hack Explained | How to Fix TV Horizontal Lines - Part 2
https://www.youtube.com/watch?v=SbGAkRgaZhs

He first measured all the ceramic SMD capacitors on the long, thin PCB to make sure there wasn't a short circuit on any of them.

He explains that the pins that are masked off on the ribben cable are clock signals on the horizontal plane, and in his case there appeared to be a short circuit in a subpixel on a single horizontal clock line on his panel after he tried reducing the block of masked off pins one by one.
The consequence of the masking is a possibly lower brightness on lines on the panel at the half where the masking is done.
He had to research a patent application to fully understand the technical implementation.
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Old 05-23-2022, 02:21 AM   #16
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Quote:
Originally Posted by Diah View Post
why you don't use the guarantee right and contact Philips since this model 2020 series..!!
I did in fact report this TV to the retailer and from there to Philips last week.
The support ticket was delegated to an outsourced service vendor in Sweden and the initial message I got from them was that they replace PCBs until the TV starts working again.
They hinted that spare parts would take a long time to get hold of and might not be available anymore for this model.
That's when I thought I'd better prepare for the worst and see if there is a reasonable way of handling this myself.
I wrote them a message in the ticket asking them what part they were expecting to replace and got no answer back, so no help from them and they certainly don't do any component level repairs anyway.
Maybe they'll come through and solve this, but if the issue is in the panel, I guess that basically means replacing the entire device.
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Old 05-23-2022, 02:50 AM   #17
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

The service vendor is right, for this model several parts are not available. I read the following at a mayor Philips parts supplier: "This item is currently unavailable due to delivery problems at the manufacturer/supplier."
It's best to ask for another tv / leniency.
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Old 05-23-2022, 03:50 AM   #18
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Quote:
Originally Posted by Maalobs View Post
I did in fact report this TV to the retailer and from there to Philips last week.
The support ticket was delegated to an outsourced service vendor in Sweden and the initial message I got from them was that they replace PCBs until the TV starts working again.
They hinted that spare parts would take a long time to get hold of and might not be available anymore for this model.
That's when I thought I'd better prepare for the worst and see if there is a reasonable way of handling this myself.
I wrote them a message in the ticket asking them what part they were expecting to replace and got no answer back, so no help from them and they certainly don't do any component level repairs anyway.
Maybe they'll come through and solve this, but if the issue is in the panel, I guess that basically means replacing the entire device.
this is not your problem if there are no parts.. you will get new TV or complete money back.. so dont miss this chance.
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Old 05-23-2022, 04:03 AM   #19
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

Indeed, don't let them off the hook, they need to be held responsible for selling junk.
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Old 05-23-2022, 04:05 AM   #20
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Default Re: Philips 70PUS7505/12 - Contrasts in image are echoed vertically upwards

I would go with refund if possible, they do not make philips like they use too.
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