YAMAHA DGX-620 LCD & Backlit Fix With NO Cost!

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Introduction: YAMAHA DGX-620 LCD & Backlit Fix With NO Cost!

There are many cases on the internet, most of the user's pickup option to change the LCD board for a new one, someone even finds the alternative (smaller size) screen. this case i will save my piano with NO COST.

Step 1:

My Yamaha DGX-620 has been having problem with screen display since 2011, right after the 1-year warranty expired, so lucky! and the problem seems to be so typical! there are many users has the same problem, the screen just showed half, sometimes worth and some time dramatically come better for a while (very soon), mostly the piano is screenless. here comes the challenge, we love the sound and we want it back to life...

first, you need to take the 4 screws from the stand, then 94 more to take off! there is only 2 size of screws, quite easy but you better put them in different cups as shown.

1) a wireless high-speed screwdriver is very important, with long tips is better

2) a smaller manual screw driver for the circuit board with care.

3) a magnetic screw finder is a plus to collect every screw from its a compartment, make the job smoother.

(PD: I forgot to take pictures of my piano, just "borrow" some from the internet, after will replace them on my own.)

Step 2: TAKE OFF THE SCREEN MODULE

the original (maybe desambled from a dead piano.....) from aliexpress sale about USD99. and if you buy a new one, does not guarantee the problem gone forever, the problem is still there, the manufacturing fault. Here, in this case, it's all about the FLEX cable! (anisotropic conductive film) , it's quite obvious when the LCD backlight runs a long time, heat rise above 60 digrees, there is where the flex cable meets tacking conditions! see here for the datasheet of the cable, you will find out the tacking condition is 60 to 90 C and bonding conditions is 140-180C

https://multimedia.3m.com/mws/media/734078O/3mtm-anisotropic-conductive-film-7376-10.pdf

so the real job is to "reflow" the flex cable to bond the sticker , this will restore the contacts.

Step 3:

Take off the main board first, then the LCD board.

find an air soldering machine may be hard for someone, but you need something to give you a precise airflow at 170C (This temperature has been edited, as the 1st time i used 145C it last only 1 month), this meets the bonding condition of the flex. I bought one for this case, it's cheaper than the stupid LCD spare part and more useful for other projects.

flow to the both sticker part for about 15 sec. then push with some force using a plastic press, repeat this job for each 2mm of distance, as the air blower covers only this range. the whole work is about 3 to 5 minutes.

(i really don't know why the pictures an up-side-down, until I find a way to edit it in instructable.com, the original pictures are fine!)

Step 4: Tricky Part of Work, Prevent for the Future!

After reflowed the flex, I decide to give some extra pressure to it, since once get heat again will repeat the story, by the name of 98 screws, I drilled 2 holes to a wasted electronic board, in attach to the original screws then cut 2 pieces of rubber and push in. as shown.

Step 5: Important Thing Before Finish

put back everything is simple, important tips:

1, Set drill's torque to 1, this is due to the structure for screws are all plastic, more torque will damage the hole.

2, Beware of speakers cables from inside of piano may cause vibrations, mine did happen once, I had to screw them again...

3, As we re-flowed the contact instead of changing them, the same problem may come back in any moment, as the room humidity, gravity, built quality all thing has to do with durability. there is no grantee from anyone, but at least, you know where is the fault and can "even temporarily" correct this.

Step 6: If Your LED Backlight Is Broken....

In the first picture, you will find the backlight cover, where the contracts are, this is a thin film that works as a diffuser.

You lift it up carefully, will see the tiny LED board just inserted there, it's connected to the power cable

Take off this board with a small nipper, and you have the board in hand, then do what you want to do.

DO NOT TRY TO POWER THESE LED WITH EXTERNAL POWER SOURCE! this will immediately damage the LEDs as there is no protection, there is no even a resistor!

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    14 Comments

    0
    Ptplopes
    Ptplopes

    1 year ago on Step 6

    Thank you very much!!! You saved the day! :-)
    It looks very simple to remove them. I wiil try this next weekend.
    regards,
    Paulo de Tarso

    0
    Ptplopes
    Ptplopes

    Reply 1 year ago

    Hello,
    This Tuesday I opened the DGX620 and checked the display. I saw no way to open it easily but when lifting a side tape I came across two (only two) backlight leds. There it was easy!
    I used two LEDs removed from a common bulb LED bulb (3000K). See attached photos.

    Regards,
    Paulo de Tarso (Brazil)

    IMG_20200421_173601[1].jpgIMG_20200421_181344[1].jpg
    0
    TqW
    TqW

    Reply 1 year ago

    It works Nicely! congret!

    0
    Ptplopes
    Ptplopes

    Question 1 year ago on Introduction

    Hello!
    I had some similar issues with my DGX-620 that showed to be due to pressure of the flat cables contacts. This was solved using a small piece of cellulose acetate cut from a 35mm negative and inserted in between the display flat cable end the connector.
    Now my problem is the backlight that stopped working. Is there a way to disassemble the display to access the back light and fix it or I need to buy a new complete display?
    Regards,
    Paulo de Tarso (Brazil)

    0
    TqW
    TqW

    Answer 1 year ago

    Hi Paulo, I have no experience of repairing backlight, are you sure they are broken? maybe its just the connector on the mainboard, with 2 pins, voltage about 3V. (see picture for location) if it's surely broken, you will have to buy a new one for backup and give a try to open it. there are sells from aliexpress cheep enough and works better than original.

    1111.jpg
    0
    Ptplopes
    Ptplopes

    Reply 1 year ago

    Hi TqW (?), thanks for the feedback. I had problems about 10 years ago with the flat cables, but not this time. I checked the 5V source direct in the backlight terminals and it was fine. If there is a way to open the display and remove the backlith fixing it will be easy.
    I did not remove the display for not to have problems with flats.
    As you removed and handled the display I figured you could give me a hint if it’s possible to disassemble and how it would be.
    regards,
    Paulo de Tarso

    0
    TqW
    TqW

    Reply 1 year ago

    You are lucky, I just did the research for you, in a minute you will see in the last section of the same post, I updated there to help others too, it's really easy.

    0
    MPBernhard
    MPBernhard

    1 year ago on Step 5

    Awesome instructions. After taking out all the screws and the board, I didn't think it was going to work because the connections on the LCD board looked perfect. But I followed the instructions exactly anyway. I have zero experience with repairing electronics but the instructions were so good that I fixed it on the first try. I especially appreciated the detail of setting the screwdriver torque to 1 so as not to strip the casing when putting it all back together. Thanks!

    0
    TqW
    TqW

    Reply 1 year ago

    Nice to know you made it! you might need to know this fix will not solve forever the issue, but it really points to the origin and able to repair it, I opened 3 times mine, as the problem went back twice, each time I put little higher flow temperature, and the 3rd time was beginning of last year. good luck!

    0
    pwregan
    pwregan

    Question 1 year ago

    Great advice. Thanks! Looking to buy one of these very cheap (because - you guessed it - screen problem!). Before I attempt to fix/replace... is it possible to play as regular piano WITHOUT screen function? My daughter needs a nice keyboard for piano practice... Hate to pass this one up!

    0
    TqW
    TqW

    Reply 1 year ago

    sorry for not replying before, the keyboard overall is functional, but not very much "pianist", it compares to CASIO more or less the same, good one to practice a few month, then let her try a real piano, you maybe need to sale it to someone else.

    0
    TqW
    TqW

    Answer 1 year ago

    Yes, you can catch the offer, the overall quality and durability are ok, as it made by YAMAHA, sound quality is decent if the internal speaker still original, or you can just connect to an externally powered speaker system. one thing I feel the keys are little noisy compared to a Casio, the strike sound, maybe the shock absorber is getting old.... Mine one is about 7 years stationary use. Hope this help.

    1
    calpesun
    calpesun

    1 year ago

    Thanks for the advice on the anisotropic conductive film cable. My DGX620 LCD was down to half screen and I wanted to avoid the cost of replacement, when it was clearly only a connection issue.
    I discovered that solder melts at around 180°C (although a soldering iron can get considerably hotter), but I decided to carefully try it. I plugged the soldering iron until the tip was just starting to 'silver' and then I carefully ran it side to side across the end of the cables. I made a few passes without stopping, at at the same time put slight pressure on the connections with a knife.
    Bit hit and miss maybe, but it worked perfectly, and the screen is back as it should be.

    0
    TqW
    TqW

    Reply 1 year ago

    Hi there! glad my note helped in solving the issue, seems it's a genetic bug of all DGX keyboards (i just can't call it piano even it sounds good, but the keys stoke feels toy). I do recommend you have a hot gun to finish this kind of job, as the iron slide quickly on the contact ribbon, maybe may become open again in a few days. good luck!