Roland XP-10 Display replacement

(and fix stuck keys)

Last week I bought a Roland XP-10 which was in desperate need of some tlc. In the photo’s it was visible that about 10 keys where stuck down. I thought these might be physically broken but according to the seller some keys just don’t come back up when you press them sometimes. Apart from that the seller said the keyboard (and display) work fine. I asked because I know the displays on these have issues.

I collected it from his front door and took it home without testing it. At home I plugged it in and nothing happened 🙂 I measured the external power supply and it read 0 volts. Right. Great start. I suspect a fracture in the cable right where it leaves the PSU because it has a weird bend in it there. I will have to look at that later. I got another Roland power supply and plugged it in. Now the screen lit up (sort of..) and a few LED’s turned red. No text on the display though. I plugged in my headphones and played the keys. At least it made some noise so the synth part seems ok 🙂 Okay.. so far for ‘the display works fine’.

Did I mention that the whole entire keyboard is covered in engine oil? Or WD40? Something greasy and disgusting anyways.. Why do people do that? To make it look ‘better’ for a sale? Every time you touch the freakin’ thing you have to wash your hands..

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Let’s take it apart!

I must say that taking an XP-10 apart is a breeze.. super simple. Very small circuit boards and a plastic housing. You have this thing apart in a matter of minutes. I removed the keybed and all the circuit boards.

Below is the original display. It has a little 14 pin flat cable that goes in a connector on the mainboard. Early XP-10’s didn’t have backlight but later models do. I didn’t see anything wrong with it but it didn’t work apart from the backlight (which only illuminates the bottom of the screen).

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Reinstalling the display or running my finger over the long horizontal flexcable you see at the bottom didn’t make a difference. So, time to find a replacement.

I’ve read a few things online about these and I’m not the first one to replace one of these displays. There is just not enough information on which display to use and how to hook it up. I have had no education in electronics so I have to figure all this stuff out. Now that I know how it works I will try to make this a how-to 🙂

The display is simple 16 character 2 line display. You can buy these from AliExpress for about 2 euro’s. I had a new one ‘in stock’ because I buy a lot of electronic parts (Arduino’s, displays, sensors etc.) from AliExpress for all kinds of small ‘future’ projects. I checked the schematics for the XP-10 (check Synfo.nl) and compared them with the pinout of the display connector on the mainboard.

This should work! 🙂

All standard HD44780 compatible 1602 LCD display’s should work.. There are only one or two models available online that I could find.. Just get the cheapest one you can find without the I2C backpack. They are available in the colors Green, Blue, Orange and White.

The pinout of the displays is compatible but the order of the pins is a little different.. you can find the pin numbers on the mainboard of the XP-10.

XP-10 Display		1602A display
Pin 1	Ground	Pin 1	Ground
Pin 2	Data 7	Pin 2	+5V
Pin 3	Data 6	Pin 3	Contrast
Pin 4	Data 5	Pin 4	Register select
Pin 5	Data 4	Pin 5	Read / Write
Pin 6	Data 3	Pin 6	Enable
Pin 7	Data 2	Pin 7	Data 0
Pin 8	Data 1	Pin 8	Data 1
Pin 9	Data 0	Pin 9	Data 2
Pin 10	Enable	Pin 10	Data 3
Pin 11	Read / Write	Pin 11	Data 4
Pin 12	Register select	Pin 12	Data 5
Pin 13	Contrast	Pin 13	Data 6
Pin 14	+5v	Pin 14	Data 7
		Pin 15	Anode (Background +5v)
		Pin 16	Cathode (Background ground)

The two extra pins are for the background leds. I piggybacked them of the 7805 regulator. (just because someone advised me to do this.. I guess you could use pin 1 and 2… but maybe there is not enough current to drive everything? No idea..)

Because the original display has a 14 pin flat cable which will never fit the new display I desoldered the original connector from the mainboard and soldered a piece of flat cable directly to the mainboard.

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I soldered the other end of the flat cable to the display except for the contrast pin which needs a 10k potentiometer so you can change the contrast.

I also put a potentiometer (500 ohms) in the anode wire powering the backlight so I can change the brightness of the display. I thought about making these controls external but I would require drilling two holes in the back of the XP-10 and use a different type op potentiometer which I don’t have right now. As you hardly ever change these settings (and it’s not possible to change them on a stock XP-10) I decided to keep them internal.

Just follow the wiring diagram about and install the potentiometers in the following way:

Pin 13 on the mainboard goes to a 10k pot and from the pot to pin 3 on the display.

Get +5v and ground from the 7805 voltage regulator and install a 500 ohm potentiometer from the +5v 7805 pin to pin 15 on the display.

Now you can set the brightness and contrast of the display. I glued in a small pcb inside the XP-10. The first photo show the place where I got the 5v from the voltage regulator (black and red wire on the pcb)

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More photo’s of the inside and the voltage regulator (which is located right next to the on/off switch:

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The 7805 voltage regulator has 3 pins. Left is input (which is somewhere between 9 an 12 volts), the center pin is ground and the right one is +5v. I soldered the wires for the backlight directly to the center and right pin.

The display worked first try! 🙂 Whoeehoeeee!!!!

One more thing: the display does not fit without modifying the case of the XP-10.. you need the trim the 2 black plastic tabs with a Dremel:

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Now you can install the display a little further to the left and install it with 2 small screws on one side. On the other side the holes won’t line up so I added small washers there:

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I you don’t do this it won’t line up properly on the front panel.

Now that the first part is done it’s time to look at the keys.

Some of them sometimes stay in the down position.. weird. I removed all the keys: put a flat screwdriver in the back and carefully spread the end tabs for the keys to come off. Be very careful because the keys break easily (ask me how I know)

I then put all the keys in the kitchen sink and washed them. I also cleaned A LOT of grease of the keybed frame thing.. I left some on it but there was a lot of grease on the pivot points..

I reinstalled all the keys and…… a lot still got stuck..

You can press a key 50 times without problems and the 51st time it will stay down. Very annoying. I removed all the keys and figured out the problem.

It’s not the pivot point at the end, it’s not the spring either. It the black tab at the front.

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Only the white keys seem to have this problem.. you can clean or lube this as much as you want but some keys will still get stuck.. either the black tabs expanded somehow or the space in the white keys got smaller.. so I thought the most professional way to fix this was to get an iron file a just make the black tabs a little narrower 🙂

Just a couple passes with the file on both sides is enough. I reassembled the keybed (after I vacuumed all the plastic grainy shit from the frame) and all keys run smoothly again 😎 Success! I learned that the Roland JP-8000 has the exact same keybed (only 4 octaves instead of 5) so this fix probably also applies to that synth.

Did I mention that my XP-10 has the famous and highly sought after ‘SRX-07 Ultimate Keys’ expansion sticker on it? 😀