Useful RT809H Universal Programmer In LCD TV Repair

By on November 5, 2018
lcd tv repair connectors

 

 

 

 

 

 

 

 

About a week ago I noticed an older used (2010) 26 inch MEDION LCD TV that someone had thrown outside next to our building’s waste container. And before I took it home for parts or for repair like any good engineer would do, I first checked if the MEDION TV model MD20174 was not too damaged, and luckily the LCD screen looked still unscratched and repairable.

I cleaned the dust from the outside case before I checked if the TV was still functioning somehow when powered on. By switching ON the power switch on the back and pushing the Standby side button the screen came on. But only for a short few seconds after which the TV didn’t react anymore on the buttons or the power switch. No matter how often I had tried.

medion lcd tv repair

So it was time to open up the TV to examine what had caused this.

lcd tv mainboard

I also checked the internet forums and searched with Google for any answers that could help fixing this older MEDION TV. But nothing could be found. Not even a schematic and certainly no service manual.




I therefore started to check with my DMM the voltages on the power supply board type AOYUAN AY130P-4HF03/04. All voltages checked out fine. So I continued by checking all flat cable connections and how they were attached to the other boards.

lcd tv power board

On following picture all connectors are shown. It shows that the four 24V power lines and the 4 GND lines (CON3) go directly to the CFL inverter board. The CON2 connector of the power supply is not used and the other connector with the four +5V power lines, the five GND lines, and ON/OFF plus +5VSB (5V standby) all go to the MAINBOARD. (Next photo shows the power board connectors).

power board connectors

connector diagram

Because I knew that I could try to extract the mainboard’s firmware with my new great RT809H universal programmer, even if the TV wasn’t giving any signs of life, I first decided to make sure I had a backup copy of the Medion Firmware of this TV. Because if the FW is lost the device will be beyond any repair and will not operate anymore. And Medion doesn’t share this with TV buyers/owners on the internet. Only a Medion MD20174 users guide can be found and downloaded.

Above backup method is simply possible because the BIOS chip on the mainboard can be read through the VGA ISP port of the RT809H when connected to the VGA port of this TV. The BIOS chip, here a 4MB eeprom, always gets 3.3V on its power pin 8 and so can be read even if the GPU/TV mainboard chip is partly defect.

I didn’t find any help or information but assumed that it was not the LCD, the inverter, and neither the CFL backlight tubes that were at fault, because I had seen them working once. Showing a perfect TV picture if only for a few seconds before the screen garbled and the TV kept silence afterwards. And that only left one possible suspect open, the mainboard. The mainboard is also the board that controls the BKL, ADJ and GND lines on the CFL inverter board. I checked the inverter board which contained a SOP 24 pin Samsung SEM2106 CFL controller chip with a 5A onboard fuse. And all inverter board components looked fine so I ruled out that it was defect. Only the mainboard that is the working motor behind all functions of this TV could be causing this defect.




Next screenshot shows that I was fully able to read, auto verify and save the MX25L3205 serial eeprom on this TV’s mainboard to my computer. With this great RT809H programmer we also simply can delete the BIOS chip of TV’s and Monitors with the VGA ISP connection, completely remove the FW after which the device no longer operates, and then write the FW back to the internal chip

(without even having to open up any device!), and we’ll notice that the TV or monitor works again afterwards like nothing happened! But of course make sure that you read and saved the Firmware first!

rt809h programmer

I was convinced that only the mainboard was defect and was afraid that hot fixing would not make any difference if the GPU/TV mainboard chip was damaged. Same problem is often the reason that many laptops do not give any visible LCD screen anymore. And in those cases only the external video port may still operate on external monitors. But even that is no certainty if that video chip or its mainboard memory are internally damaged. Reballing and/or replacing any defect chips would make sense but is a very tedious job without any warranties on success at all! Luckily to my surprise I found a seller who still sold a used but good working mainboard. These Medion TV boards are apparently also known as Foehn & Hirsch FH-26LMH – Main AV – MSD306V4.0-A (MSD306V40A) boards. And for 25 Euro and 16 Euro shipping costs I only waited 2 days on my replacement board. Which today arrived and of course was immediately tested. The MEDION MD20174 came indeed back to life and the repair was a great success! Without the IR control (which likely was still kept by the previous owner) my Dreambox DM800HD se with super Japhar SIM OpenPLI6.0*** was connected to the scart port and the TV showed some great screens of which I will add a few screenshots after following mainboard photos (Top and solder side). Following photo shows the top left side of the mainboard.

lcd tv mainboard repair

Next photo top mainboard side with the GPU/TV chip top left and the DVB-T tuner right below.

how to fix lcd tv mainboard

how to repair lcd tv mainboard

Photo below shows mainboard bottom/solder side with model/version labels.

fixing lcd tv mainboard

repairing lcd tv mainboard

Next photo more closely shows the components on the TV mainboard. With step-down mp1582en.

mp1582en ic

lcd tv repaired

Bad news is showed on TV by beautiful ladies to make all misery bearable.

how to fix and repair lcd tv

In previous photos also three LM117 regulators are visible on the mainboard component top side.

lcd tv repair and fix

Thank GOD for creating la femme and making electronics possible!




After this repair only a small white point on the left part of the screen marks the spot where the outside screen was slightly damaged by the previous owner but with such beauties it is hardly noticeable. And nothing is perfect although above ladies come extremely close! Until another repair!

Albert van Bemmelen, Weert, The Netherlands.

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Note: You can read his previous repair article in the below link:

http://jestineyong.com/6-usb-charger-repaired/

 

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17 Comments

  1. Robert Calk Jr.

    November 5, 2018 at 3:59 pm

    Good job, Albert. Thanks for sharing the repair with us.

    Likes(3)Dislikes(0)
    • Albert van Bemmelen

      November 5, 2018 at 4:34 pm

      By-the-way: Your JYE DSO-15001K Oscilloscope KIT tip was very useful! I bought it through Banggood and got it very soon for about 17.22 Euro. Only had some wrong R1 and R2 components in my kit where R1 was 506.6k instead the in the manual given 510k. And R2 was 5833k instead the needed 5.1Mohm value. And some screws were missing and too short to hold the frontknob board, why I used two of the longer 8mm screws for it. But I kept those resistors and the scope works splendidly! I guess that the white line on your display is from a faulty LCD or caused by a bad connected flexprint? I find this miniscope very useful to check on videosignals in TV's and on Scart/RCA cables.

      Likes(1)Dislikes(0)
      • Robert Calk Jr.

        November 6, 2018 at 7:40 am

        Yeah, it's a nice little scope kit. I'll look it over one of these days.

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  2. Albert van Bemmelen

    November 5, 2018 at 4:14 pm

    Thanks Robert! How is your Tektronix 2465DV Fan motor repair going? I guess buying a new Fan is not possible?

    Likes(1)Dislikes(0)
    • Robert Calk Jr.

      November 6, 2018 at 7:59 am

      I have held up Part 1 of the Fan Motor articles because I don't want their to be too long of a time gap between them. Part 1 of the disassembly has 26 photos in it. I could put 75-100 photos in it but I have to limit the number to a decent amount, especially since I use full size photos instead of tiny blurry ones that you can barely see. Plus there are always setbacks and other things popping up that need attention.

      I also need to get a digital scope. I was planning on getting a digital scope anyway, but my Tek scope fan needing rebuilding has forced me to hurry up and get one now. I have spent the last few days doing almost nothing but studying up on digital scopes and different kinds. And Sundays are reserved for playing with my grandbabies!

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  3. Parasuraman S

    November 5, 2018 at 6:56 pm

    Excellent as usual exposing the real unrelenting hunter in you!

    Likes(1)Dislikes(0)
  4. Albert van Bemmelen

    November 5, 2018 at 11:09 pm

    Thank you Parasuraman. I hope I will be still able to correct the error in the still defect original TV mainboard. Now that I know the right voltages as measured on the replacement working mainboard with good working TV controller chip. Which of most voltages couldn't be measured on the defect Medion mainboard. As they also were mentioned in the drawing :

    Voltages on coils L17 + L16: +1.55V DC

    Voltage on pin 1 MP1582en : +1.32V DC. (same on old defect board!)

    On/Off signal voltages: +4.33V DC/ 0.12V DC

    BLK voltage : +4.90V DC

    ADJ Voltage : +3.73V DC

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  5. Humberto

    November 7, 2018 at 12:38 am

    Great repair Albert. Thanks for sharing your experiencies in this Blog.

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    • Albert van Bemmelen

      November 7, 2018 at 3:35 pm

      Thanks Humberto. After fixing this Medion I still need a matching IR remote controller. So I tried all my 5 different programmable universal IR remotes but none worked. And I couldn't find the right code for this MD20174 Medion tv why I bought another USB programmable universal IR remote from this firm: https://superior-electronics.com/ on eBay.
      Their programmer software database with over 260.000 codes is free and I bought an USB 4in1 Superior model and another IR programmer for my older standard also Superior type 4in1 remote. So I will be able to program two Superior remotes for hopefully any device in my home including the Medion tv. I hope that the available Superior database codes for Medion tv's type md20170 and md20171 do work with my repaired tv.

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      • Albert van Bemmelen

        November 7, 2018 at 9:38 pm

        Good news on the SUPERB universal SUPERIOR USB programmable remote controller which I received superfast today! Above Medion codes didn't work for my MD20174 tv BUT Medion code MD20272 worked perfectly! So I think that this Superior USB 4in1 remote controller is a must have and also a very affordable device!!! Programming only took a few minutes and is SuperEasy!

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  6. Christopher Massie

    November 7, 2018 at 1:40 am

    A very excellent no B.S.troubleshooting exercise! Thank you Albert. I don't work on tv's but I will save this article for future reference since the opportunity may come my way someday.
    Vielen Dank!
    Das Allerbeste

    Likes(0)Dislikes(0)
    • Albert van Bemmelen

      November 7, 2018 at 3:23 pm

      Thank you Christopher. Like you I normally do not repair tv's. Simply because without schematics or service manuals they are very hard to fix. But occasionally they find my way like the Medion tv in this article. Which makes it more interesting to invest some time and money on trying to fix them.

      Likes(1)Dislikes(0)
    • Robert Calk Jr.

      November 7, 2018 at 7:50 pm

      Hi Christopher,

      I am glad that I worked on my TV. After disassembly and troubleshooting, all I had to do was remove the first pair of LED strips, resolder the LED's on the first one, and adjust their LED strip coupler pins. It would have costed me $300 - $400 to buy a new TV had I just thrown it away and bought a new one like most people do.

      I may have found one for a little less than $300 if I caught it on sale. I replaced the primary e-cap and removed the factory glue for good measure since I already had it opened up. That saved me money that I used toward buying a new digital scope!

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  7. Albert van Bemmelen

    November 7, 2018 at 8:29 pm

    You are right Robert that doing the job ourselves saves us a lot of money that otherwise would have gone lost on cost of labor alone. Repairing the backlight of LCD tv's however will always be a tricky job if it involves replacing single LEDs on the backlight strips. Some of the backlight leds in our LG in a previous repair caused problems again after a week or so. Why replacing all old strips by completely new original strips is I think the best advised method to follow. Although also the most expansive solution.

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    • Robert Calk Jr.

      November 8, 2018 at 3:10 am

      I am sorry to hear that the TV started acting up again, Albert. You probably should have went ahead and resoldered all of the LED's. My TV is still playing well. But from now on when I do a repair like that, I will go ahead and resolder every LED since I already have the TV apart.
      I ordered 100 LED's from China so I will have some in the future if I have to replace some. I now have a good board preheater so I can do a better job replacing LED's if the need arises.

      Likes(1)Dislikes(0)
  8. albert van bemmelen

    November 7, 2018 at 11:49 pm

    I meant 'expensive' of course.

    Likes(1)Dislikes(0)
    • Robert Calk Jr.

      November 8, 2018 at 11:21 am

      Yeah, I knew you did:)

      Likes(1)Dislikes(0)

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