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Rusty, Music Professional
Category: Electronic Musical Instruments
Satisfied Customers: 5883
Experience:  Sound Engineer, Electrical Issues, Tone Consulting
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I replaced the touchscreen on my Triton Studio 88 keys

Customer Question

I replaced the touchscreen on my Triton Studio 88 keys because was bad, and after that the display just turns blue without characters. I know that the new touchscreen works because when I touch it a bip sounds. Also when I turn the contrast potenciometer the display looks like change it a little bit to dark. I checked that potentiometer and gives 1.2VDC to 2.8VDC to the KLM2091 board (LCD inverter). How can I know if the LED or KLM2091 or the main board (KLM2283) is bad?
Submitted: 6 months ago.
Category: Electronic Musical Instruments
Expert:  Rusty replied 6 months ago.

Hello, my name is***** to Justanswer! Give me just a few minutes to look up some specifics, I'm working on this now.

Expert:  Rusty replied 6 months ago.

Do you still need help with this?
*This is not your answer, just an inquiry to see if you still need help. I'm here to help when you're ready. Due to the nature of the problem, it may take a few tries back and forth before we finish the troubleshooting and fix the problem.

Customer: replied 6 months ago.
Hi Rusty. Nice to meet you. Yeah. I am ready.
Expert:  Rusty replied 6 months ago.

If it's the backlight that isn't working, you can shine a flashlight into the display, and you'll see the characters. Since it's blue, try that first to find out. I think you'll find that a ribbon cable was not seated properly during the replacement, unless you see characters with a flashlight. If you do, change the backlight.

Customer: replied 6 months ago.
Is the backlight the small LED behind the LCD that iluminates the whole screen? If yes, this one is working, because the LCD is iluminated in blue. I will check again the ribbon connection, when I noticed the characters don't pop up, I cleaned the ribbon and slot with DeoxIT D5 cleaner thinking a bad contact, but not successful.
Anyway. I will check again the connection.
Expert:  Rusty replied 6 months ago.

Deoxit is the stuff to use, but sometimes the ribbon doesn't always align properly. They are a pain. Yes, the LED is the backlight for the whole screen.

The other thing that can go out is the IC that sends the characters to the screen. If that goes bad, you'll need to replace the module that the LCD plugs into.

Customer: replied 6 months ago.
Is there a way to know if that IC is sending the characters information properly? I mean, an specific voltage range. I will follow the LCD lines until reach the IC and I will look for his datasheet.
Expert:  Rusty replied 6 months ago.

That's getting a little above my pay grade... Basically if you are sure the contacts are lining up on the ribbon, on both ends, and it still doesn't work, and you are certain that the LCD works, then the IC is dead.

Customer: replied 6 months ago.
I have ordered the LCD. I will install it when arrives. And I let you know.
Expert:  Rusty replied 6 months ago.

You did read the part about the IC that sends the characters to the LCD, correct? When there are no characters, and the rest of the machine works, it's either the LCD or the IC that needs replacement. The IC you would have to order from Korg.

Customer: replied 6 months ago.
The IC is the M66271FP. I will wait for the LCD, if stills the issue, I replace the IC. I let you know.
Expert:  Rusty replied 6 months ago.

Sounds good, you're on the right track.

Customer: replied 5 months ago.
What's up. Yesterday arrived the display. I replace it but still the same problem. No characters. I re-check the wires from the IC to the display ribbon, and all are ok, some of these wires have SMD solenoids, these are good. Continuity end to end.
Expert:  Rusty replied 5 months ago.

The IC is the only other part that would prevent characters from getting to the LCD. That's the difficult thing with LCDs and ICs on keyboards, it's hard to tell which part is bad until you replace either one of them.

Customer: replied 5 months ago.
Ok. I will buy it. I let you know fella.
Expert:  Rusty replied 5 months ago.

It should do the trick. LCD screens are the only parts where we have to flip a coin between replacing the screen, or the IC.

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