How do I fix a Yamaha MM6 keyboard display that is working on half of the screen but showing lines on the other half

Your battery has died and you've lost the sound info, Contact Yamaha in your area to find a service center to place the battery and reload the data.

only few technician could do some repair with the screen card or the connections fron screen to cards very complicated usually the screen goes off totally only few could do it luckily by chance.
you need to change the screen i suppose

Probably the transpose button on your keyboard has become short. You need to clean the contact by a cleaning agent such as WT-40 or similar one. If not, you need to change the button.

My Yamaha MM6 Synth is showing blank (white) screen when switched on. Keyboard sounds and banks are working. Everything looks nice but not showing any details on screen. Any help.....

It kinda depends on if a hammer is broke or key is broke. Or if a foreign object is stuck in there. Typically not hard if you can remove screws and remember how they go back in. TypicAlly the bottom panel comes off keyboards ( start by removing those screws ) or the top case will fold up ( still bottom of keyboard screws ) then multiple screws to realease keyboard assembly. May have to disconnect some wires/ ribbon cables so have a sharpie ready to label to ensure correct reassembly. Then it's all about if they have separate keys or a keytree or sometimes just removing ba key and reseating fixes sticking problems. Get yourself a can of blow off or contact cleaner just in case. Not sure who locally to you sell parts but you can always call manufacturer and ask who does their distribution for parts.

Usually that is a programed feature, but you can try the support center at the manufactures website.

The defect is likely failure of the LCD module and the connections to the glass sandwich... it is likely fatal to the module... If you are adept with tools a bit, you can probably replace it yourself... You have to go slow and be careful to keep track of where stuff goes.

One has to be real careful to not damage the ribbon cables that connect between the upper and lower shell. I suggest having two people present to handle the shell when opening it. Have a good work surface and organizer cups or bins to keep screws seperate. There will be a LOT of screws from the back to remove to seperate the halves. DO NOT force anything.

You can probably order the part... Call Yamaha America Music support and ask for parts dept to order the part... I suspect it is a bit pricey. While your at it, inquire if they can sell you a service manual for the keyboard... they used to do this for $15 and you could get one with your order. The manual for the Tyros I got is very complete showing all the internal and assembly procedure.

I had the same problem. This is how I fixed it:
1- Lay the MM6 upside down, remove the screws, open the back panel.
2- On your right side (the Volume PC board section), you will see component stand up (2 of them had 3 legs each, one of them is had more than 3 legs don't remember exactly) but 3 of them all had metal finish on their back. There are look like Power Transistor ( I do not have a schematic to be sure) but when these part get warm or hot (volume is only decrease when MM6 had been Turn-On for awhile), caused the volume to decreased.
3-Go to Radio Shack or other electronic stores, buy 3 HEAT SHRINK or you can make them your self (find- google to see what it look like, marterial...etc);
4- Use small screws and nuts, install these HEAT SHRINK into these 3 component then they will help these 3 components to stay cool all the time, therefore it will fixed the Volume decrease problem.
5- Yamaha should put HEAT SHRINK into these part when they designed.

If this s a common known problem, perhaps there is a recall on the instrument. Contact Yamaha directly to inquire.

I brought the keyboard into a local service technician. He told me that he had to remove about 50 screws but the solution was simple. He unplugged and reconnected the ribbon connector. It apparently was not making good contact.