XP-50 LCD displays jumbled characters

[xcevinx]

Problem: Upon startup, XP-50 LCD display shows random jumbled characters - mostly exclamation marks. The jumbled mess is completely unreadable, and once some buttons are pressed (such as disk/utility), the gibberish jumps around on the screen in a chaotic fashion.

The LCD display brightness works properly. The audio outputs function properly. It appears all the patches work, except the user patches which are completely silent. I have just replaced the CR2032 battery and cleaned the interior with compressed air.

I am the original owner. It has been in the shop one time (for the same jumbled text problem) about 10 years ago. Maybe three months after getting it back, it started happening randomly again, and after six months the synth became completely useless. Recently, I’ve had the desire to get this synth working again.

Has anyone had similar experiences or know what the issue might be?

Thank you in advance!

[AncientGeek]

With respect to the user patches, did you do a factory reset after replacing the battery? If not, you should do this. The RAM contents, including all user patches, will be empty/random after changing the battery. A factory reset re-initializes the RAM and copies factory presets to user patch space.

If the jumbled text issue first occurred 10 years ago and no other symptoms of capacitor failure are present, then I'd be inclined to suspect either the LCD module itself, or the ribbon cable connecting it to the main board. A faulty ribbon cable connection would be my first point of investigation.

Good luck.

[xcevinx]

I desperately tried to perform a factory reset, but nonsense characters jumping around on the screen made it impossible. While the LCD is nice and bright, it is absolutely worthless for viewing or changing any settings.

Thank you for the response - I will attempt to track down the LCD ribbon cable first as you suggested. I did not see any capacitors leaking on the PCB's at first glance. I'll pull the main PCB out, along with my multi-meter and get a magnifying glass to inspect thoroughly.

[AncientGeek]

It's possible, indeed sometimes essential, to do a system reset without being able to see the display. Use the following key sequence:

1: Disk/utility
2: Number pad 4
3: Number pad 5
4: Enter
5: Dec
6: Enter again.

This will reset everything, including the LCD contrast. The following keystrokes can be used to adjust the contrast:

1: Press System
2. Press switch number 2 in the 'tone switch' row at the top
3. Use the scroll wheel to adjust the contrast.

Good luck