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Old 09-09-2011, 05:54 AM   #21
stevekasian
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Default Re: Sanyo DP46848 screen half dark

Hi PlainBill... So, just to interject here, as I am looking at one for sale on craigslist with the exact same problem right now for a hundred bux, are you saying that this is an irreparable malfunction, or is there a part that can be purchased and/or work that can be done to fix it?

Thanks,
SK
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Old 09-09-2011, 07:17 AM   #22
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Default Re: Sanyo DP46848 screen half dark

Quote:
Originally Posted by stevekasian View Post
Hi PlainBill... So, just to interject here, as I am looking at one for sale on craigslist with the exact same problem right now for a hundred bux, are you saying that this is an irreparable malfunction, or is there a part that can be purchased and/or work that can be done to fix it?

Thanks,
SK
I'd suggest you do a little research to fill in the details, but here is a summary of the assembly of an LCD panel as I understand it.

The actual LCD panel is a sheet of glass with the pixels deposited on it. Pixels are addressed by turning on a particular combination of X and Y data lines. Conductive strips run horizontally and vertically to the edges of the panel.

In a small (watch) LCD display contact between the conductive strips and the control electronics is made by a narrow 'rubber' ribbon with alternating conductive and insulating layers (Zebra strip). When one edge of the ribbon is against the glass panel and the other against a strip of contacts, continuity is established. This is maintained by a clamp which squeezes the three parts together.

This is impractical for large panels. Instead, a special adhesive is used to bond a flexible conductive strip to the glass panel. During the bonding process the adhesive becomes conductive 'vertically' - between the conductive strips on the glass panel and the conductive strips on the flexible conductor, but not 'horizontally' - between adjacent conductors on either surface.

This process is very temperamental, and the bond is prone to failure. When the flexible conductive strip pulls away from the glass the drive signals are lost. A temporary solution is to insert pads to force the strip and the plate together, but this seldom works for very long. It is my understanding this can be repaired, but it requires specialized equipment and techniques. In other words, 'Very Expensive'.

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Old 11-19-2011, 10:59 PM   #23
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Default Re: Sanyo DP46848 screen half dark

I had the same problem, and I don't know anything about fixing TVs or working on TVs, but I fixed it for now.

I took the whole TV apart while it was plugged in and had a show on (so I could see if what I was doing was working). At first I focused on the board on the left side of the TV (on the back side of the screen). Before the problem got worse the picture would clear up for a second when I hit the screen, so I figured it was a connection problem, but then the problem got so bad it would never go away. There are 15 or so chips with wires running to them on the board on each side - I checked them to make sure the were connected.

Meanwhile, I'm banging away on anything and everything inside the TV and nothing's working. Finally I traced the wires on the left side to what might be the "main board" in the middle (behind the access panel on the back of the TV). I took off the metal guard (with lots of holes) that protects the "main board" and pushed on all the places where wires connected to "chips" connecting to the board. Something there did the trick and the picture cleared up completely. There are wires that go from this "main board" (in the middle behind the access panel in the back) to the board that runs along the left side of the TV (behind the screen). Check those connections on the "main board" and all the connections around that. I just pushed on them with my finger.

So far so good.

MM
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Old 08-10-2012, 02:20 PM   #24
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Default Re: Sanyo DP46848 screen half dark

I've got a DP46848 that had the same thing. The left half of the screen was very dark and faded. I replaced the backlight inverter and it kept doing the same thing. I finally figured out that it is a problem with the ribbon cables that go from the t-con board into the LCD panel itself. I put electrical tape on the back side of those ribbon cables and carefully reassembled the tv and problem is solved. I've moved it around quite a bit and could not get it to create the half-lit screen again so hopefully this is a long-term solution.
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Old 08-10-2012, 02:26 PM   #25
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Default Re: Sanyo DP46848 screen half dark

I'm sorry, let me clarify.
The ribbon cables run from the long strips that are inside of the frame into the LCD panel, they are not connected to the t-con board.
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Old 08-28-2012, 03:52 PM   #26
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Default Re: Sanyo DP46848 screen half dark

I have a dp46848 with a half black screen. Is there any chance if this being caused by a bad cap. I so does anyone have pics showing the problem cap or caps and the repair itself.
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Old 08-28-2012, 04:05 PM   #27
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Default Re: Sanyo DP46848 screen half dark

I had a Samsung LCD that had under-sized caps on the start up board installed by the Manufacturer, I guess to save money. However, the manufacture was forced to fix the problem or recall the whole TV. So I called an number given from internet client who had her TV fixed free. I called the number and they set up an appointment then came to my house replaced 3 caps with factory issued over-sized caps in less than one hour. The Technician that came said his company got $150 for the repair and he had 6 calls to do that day. My TV was 2 years old and out of warranty but it paid everything. I'm wondering if the dp46848 Sanyo might have the same deal going to happen to them seeing this many people having the same problem.
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Old 09-01-2012, 03:15 PM   #28
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Default Re: Sanyo DP46848 screen half dark

I was trying to follow the instructions you posted here and as I removed the metal cover with the lots of holes, the bottom right corner of the metal cover touched something on the bottom right of that yellow board. There was a spark and now the TV won't power on at all. Suggestions?


Quote:
Originally Posted by mrmusichead View Post
I had the same problem, and I don't know anything about fixing TVs or working on TVs, but I fixed it for now.


Meanwhile, I'm banging away on anything and everything inside the TV and nothing's working. Finally I traced the wires on the left side to what might be the "main board" in the middle (behind the access panel on the back of the TV). I took off the metal guard (with lots of holes) that protects the "main board" and pushed on all the places where wires connected to "chips" connecting to the board. Something there did the trick and the picture cleared up completely. There are wires that go from this "main board" (in the middle behind the access panel in the back) to the board that runs along the left side of the TV (behind the screen). Check those connections on the "main board" and all the connections around that. I just pushed on them with my finger.

So far so good.

MM
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Old 10-31-2012, 07:15 PM   #29
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Default Re: Sanyo DP46848 Black Lines Advise

Quote:
Originally Posted by rhino18e View Post
I have this TV that when I turn it on the left side of the screen is dark, then after about 10 to 20 minutes the left side (which I think are the backlights) will start to flicker and then will come on and stay on until I turn off the TV. Then if I turn it back on it does the same thing.
Any help would be appreciated

Thanks in advanced
As you can see in the pic, I have some small black lines that seem to be fixated on the screen all the time, Then I get more blacks lines that are flashing when the images get bright and/ or flash. All at the the top 1/3 of the screen

I have pulled both boards that are mounted to the back panel, checked and reflowed many solder joints (None looked cracked). Also taped down all wires and ribbon cables, crammed foam rubber between the 4 ribbon cables that goes from thr T-Con board to the LCD panel, at the top. After all this, The TV seems to work good, but when it warms up good, It starts to get the dark shadowy flickering. Is it worth replacing the Master & Slave boards?
Thanks........ Sick over my LCD....
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Last edited by TubeJunkie; 10-31-2012 at 07:18 PM.. Reason: Spelling
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Old 10-31-2012, 07:40 PM   #30
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Default Re: Sanyo DP46848 screen half dark

The inverter is fine. Your problem is with the LCD, and unfortunately, it is likely to be unrepairable.
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Old 11-25-2012, 02:36 PM   #31
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Default Re: Sanyo DP46848 screen half dark

What about the grounds inside the case that flex as it is re assembled? has anyone tried this? also where they contact could be dirty. Im going to diss assemble mine today and see if I can "see" a difference.
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Old 01-01-2013, 03:03 PM   #32
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Default Re: Sanyo DP46848 screen half dark

I hate to dig up this thread again, but I (think) after over a year with this issue, I finally solved it. Hopefully.

This morning I was feeling a little brave. Actually, more like I've been sick in bed and trying to watch the stupid thing I got frustrated and grabbed my laptop. After digging through the web for hours, I came across a video that was VERY helpful in solving this case. This video here: http://www.youtube.com/watch?v=purk_SyiT44

This isn't the same TV, and it isn't even the exact same problem, but it's close. It led me in the right direction. Since I can't stand being sick, and I hate even more to be laying in bed trying to watch that PITA television, I grabbed a screwdriver and got busy.

This is probably the 5th time I've tore this thing apart. But this time I didn't have to go as far. The only thing that needs to be removed is the front bezzle by removing the screws around the outside on the back. The front bezzle comes right off, so be careful, especially since the speakers will still be connected, so just carefully lay the bezzle down in front of the TV. This will reveal the metal frame around the LCD. This also needs to come up. There's a number of screws around the outside on the very front of the frame. Take those off, and that frame will slide right off.

After the LCD frame is off, you will notice the 12 ribbon cables along the top of the screen. You can see them clearly in the video I posted. I went ahead and plugged the TV in and fired it up. When it was on, I lightly pressed on the front of those ribbon cables to see which one was causing trouble. For me, it was the 2nd one from the left. I had a few pieces of one-sided sticky foam laying around, so I cut it up into 12 pieces and stuck it on the front of each of those ribbon cables. I put a piece of electrical tape over the top for good measure. While the TV was on I grabbed the metal LCD frame and put it on. As soon as I got the first screw in on the left side, boom, the problem came back even worse. The left half of the screen stayed solid dark, unlike before where it was just flickering. So I drew a conclusion that putting MORE pressure on those ribbons made it worse. I took the frame off again, and removed the tape and foam from the ribbon that was causing problems. I even removed the rubber piece to the corresponding ribbon on the top inside of the metal frame. I tossed the frame back on and the picture was like brand new. It's been on all day without a single problem. I'm sure this is only temporary, but I'm glad to be able to enjoy my TV at least a little while longer.

If you're having this same problem, the first thing I would do is remove the rubber on the inside of the frame for the cable that is causing you problems. If not, you could always go the other way and add pressure by using some foam or rubber or whatever you have laying around. The best thing would be to check out that video, everything was explained very clearly and it was very helpful.

Good luck, and Happy New Year!

Cheers.
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Old 02-22-2013, 09:36 PM   #33
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Default Re: Sanyo DP46848 screen half dark

My tv is the same model and is doing the exact same thing. it is dark in the left side when you turn it on and some times it freeks out a little in color lines but as soon as the tv warms up it starts working fine and i left it on for days and it works great till i turn it off again. I was going to change the boards in the back but if I could narrow it down I would like to. I was thinking power inverter board but any help would be great.
thanks all
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Old 02-22-2013, 09:45 PM   #34
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Default Re: Sanyo DP46848 screen half dark

missed the posts about the ribbon cable so ill try it tomorrow and ill post my results. thanks all
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Old 06-08-2013, 12:56 PM   #35
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Default Re: Sanyo DP46848 screen half dark

This is kind of a half-assed way to fix it, but I removed the metal bezel, which in turn relieved pressure from the ribbon cables. Guess what? Problem solved! I reassembled the TV without the metal bezel and the fading in the left side of the screen is now gone. :-)
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Old 06-08-2013, 01:01 PM   #36
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Default Re: Sanyo DP46848 screen half dark

Yeah, that's not going to fix it, because you need to keep pressure applied to those ribbons.
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Old 06-15-2013, 04:00 PM   #37
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Default Re: Sanyo DP46848 screen half dark

Picked up a DP46848-00 with the same problem. Following the process documented in the YouTube video linked by Tom got it to show a full picture. I hate to call it fixed. This one was given to me. I'm going to pass it on to a friend. That way I can keep an eye on it.
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Old 07-19-2013, 03:33 AM   #38
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Default Re: Sanyo DP46848 screen half dark

I have a 42lcd inch sanyo lcd tv with the right side. Being less bright than the right. Going to try some of the suggestion and check back in tomorrow.
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Old 07-20-2013, 04:08 PM   #39
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Default Re: Sanyo DP46848 screen half dark

I had the same Make/Model TV in shop. The right side of the screen was dark and would vary brightness. It was not the T-Con. It was the COF flex cable on the far right top of pannel. Pushing on the flex cable bad the picure clear and bright. Placing a little pressure on it and reassembling screen was a temperary fix that prolonged the enevitable failure.B
Because I did not actually repair it or replace parts I only charged te 25 dollar exam fee.
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Old 12-11-2013, 07:51 PM   #40
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Default Re: Sanyo DP46848 screen half dark

you all have given me great insight to the problem..........removed the metal frame and took a chance.........left side came back up........kudos screen looks great.......will reinstall with and then without the pad........wish i could just put a heat gun on the strip that is the issue......most outer ribbon to the screen.......hoping for the best thanks again
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