Roland XP50 LCD Display Problems

Have just mailed you one. Good luck my friend.

Hi Richard,
Thanks for your kindness sending the schematic, though I have not received your message yet. But I ended up buying it on eBay, so I have it now.

My XP50 had the same problem of yours: display backlight is lit (orange) but no characters appear on it. This is a problem on contrast adjust circuit.

Actually I have a lot of skills in electronic (engineer), and I analyzed the schematic and found a solution to the problem the problem:

The circuit formed by IC17B (opamp), C83 and C63 are responsible to adjust the LCD contrast using PWM technique, acting as an integrator.
So this circuit is responsible to integrate the PWM signal and converting it to a variable voltage output (-0.6 to +0.96vdc). Then this signal is applied to the pin number 3 of connector CN14 (responsible for the contrast adjust of LCD).

-1st solution (more correct): replace C83 and C63, in my case these caps were opened (without capacitance, because they leaked).
The values of C83 and C63 are 1uF x 50v (pretty cheap).

-2nd solution (no need to replace the caps): just remove the wire that is on pin # 3 of CN14 and solder this wire to the ground of PCB mainboard.

Note: be careful when disordering / soldering the components on motherboard, use a 20watt iron solder, otherwise you can damage the copper wires of PCB.

I hope this help you and in case of doubt let me know.
Julio.

Here is a pic showing the location of contrast adjust circuit and caps.

I have already replaced C901, C902 , C65, C83 and C63, but the problem remains.

Does anyone have other solutions?

Thank you.

Update:
As I have explained, in my case the caps C83 and C63 leaked and I forgot to mention that the liquid (electrolyte) corroded and opened a superfine PCB wiring that connects the R74 and R73 and the pin 7 of IC17B. I detected it with an OHM Meter.

It was just to repair this PCB wiring (soldering a jumper wiring) and the display returned to work fine.

Also, you should consider this simple solution:

-2nd solution (no need to replace the caps): just remove the wire that is on pin # 3 of CN14 and solder this wire to the ground of PCB mainboard.


Good luck.

Hi Cesarsound,
Thanks for your help.

I already according to succeed of repair LCD problem.
But have a new problem is have no sound output,
In test mode all buttons and keyboards contain sound, just sound very low.

Excuse me, do you have other solution to repairs?

Thank you.

do it have some sound on headphone output?

please give more details.

Under the general mode, there is no any sound output.

But at [TEST MODE ] 4. SW&LED test, All buttons & keys have the piano sound output, just the volume is very low.

Sorry for my poor English.


Thank you.

Here are some tips you should try:
1-Do a factory reset.

2-Connect another keyboard to the XP50 via MIDI (MIDI IN) to see if the sound generator responds or if the problem is on keyboard keys scan circuit.

3-Replace all electrolytic capacitors, especially the C931, C932 and the caps that are on analog signal path like C6, C7, C8, C11, C174, C175, C86, C90.

4-Test all the muting circuits that that composed by:
A: Q13, Q14, C902 and IC37 are the muting circuit of DA converter - you should read a voltage of aprox. 12-15vcc on pins 7 and 8 of IC19 (the 18bit DA converter).

B: IC1A, Q11, Q1, Q2, Q8, Q9 form the output muting circuit. You should read a voltage of aprox. 0 to minus (-)5vcc on junction of R148 and R132 to have sound on output (muting off).

5-Test the direct output of DA converter: Check if there is sound on pin 11 and 6 of IC19 (the 18bit DA converter). You should use an oscilloscope or an audio amplifier here.

6-Do a visual inspection on all PCB wirings of motherboard using a magnifying glass, to see if there is some trace of leaked electrolyte from capacitors, because the electrolyte can destroy the PCB wirings. If you find a damaged wiring, you should try to reconstruct it.

I am considering that you have some Electronic Technician skills to work on motherboard. Otherwise you may damage definitively the motherboard.

PS: my XP50 is working perfect now, with a clear and punch sound.
Good luck.

Help anyone, I have the same problem with my xp 50 with the display being blank. I have read on the forum that it can be fixed by relpacing the caps. So can anyone email me a schamatic or the value and location of each caps that needs to be replaced on the mainboard so I can get the right caps. Any help will be appreicated. My email address is ezgee45@msn.com, thanks

To add to excellent answers in this thread - my experience with my XP-50,
in hope that it could be of some help to fellow XP-50 users.

Even thou my XP-50 was for a couple of years in storage, it started
developing similar problems. LCD contrast got messed-up, and it was not
possible to change it, XP-50 was changing modes on its own will, etc.

After disassembly, and close examination I found damage to PCB traces
around electrolytic capacitors (problem is confined to mainboard PCB,
top side only, I think).

I decided to replace all electrolytic caps. Here is the complete list of
all caps from the top side of the mainboard:

1 uF 50V x 2
10 uF 16V x 14
4.7 uF 50V x 1
100 uF 6V x 3
330 uF 6V x 2
47 uF 6V x 5

As mentioned before, all components are surface mounted (SMD),
so, unless you have skill and facilities to deal with soldering SMD
components - send your XP-50 mainboard and caps to qualified
service which can do caps replacement, and examine / fix damaged
tracks as well.

My XP-50 works like new now =)

Special thanks to Cesarsound for lots of useful information on the
subject.

Hi domu,
Thanks for the compliment and for the additional tech information.
This is the way, let's help each other.

Cesarsound.

Hi, pls could someone post me a copy of the xp50 schematic? I have a similar problem with my LCD. Just went blank with only the backlight showing. My email addy is kachilala@yahoo.com. Thanks.

Hi,
Do this simple task:

-just remove the wire that is on pin # 3 of CN14 (white connector) and solder this wire to the ground of PCB mainboard.

Let us know the results.

hallo, heeft iemand een schema van Roland xp50.
de probleem is telkens bij inschakelen valt de sound weg
na 10 seconden.
weet iemand waar het aan zou liggen.

bij voorbaat mijn dank,
 
benbas