Roland XP50 LCD Display Problems

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Re: Roland XP50 LCD Display Problems

Postby mp3ireland2 » 13:19, 27 January 2016

THanks for the link and the info!
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Re: Roland XP50 LCD Display Problems

Postby Horizonsound » 00:51, 28 January 2016

Hi All,

I recently picked up an XP50 through ebay (not working). This one obviously had a hard life.
Battery replacement and factory reset got it to operate initially.
The disk drive was seized, but managed to free up the drive motor and now it works. Note, these are SHUGART drives, so a replacement was rather difficult.
The expansion board only recognised EXP-A position, but after cleaning up the connectors on the other three, managed to get those running as well.
The encoder was erratic. I've got a new one on order from Syntaur, as I could not find a direct replacement for the part no. through element14 or mouser. They are obsolete.
Many buttons are starting to fail. Replacement on their way.

The big issue now is that the keyboard is freezing after being turned on for 10secs. Display goes dim (characters are slightly visible), but nothing responds, and no sounds. Voltages seems to be all good when it goes into this state.

I'm going to replace all the caps when they arrive.

FYI, i've fixed up a number of JV synths recently, including a JV80 with the dreaded red-goo (easy fix with NaOH) and many broken PCB traces, and a JV35 that had beer and tobacco all through it!

If anyone has experienced the freeze issue before, please let me know. I'm suspect of C65 with is in the reset circuit(?)

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Re: Roland XP50 LCD Display Problems

Postby Horizonsound » 08:20, 28 January 2016

I replaced C65 for the time being with a 10uF (in lieu of 4.7uF) and it seems to be running fine now...
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Re: Roland XP50 LCD Display Problems

Postby Jazzbassist220 » 20:17, 21 November 2016

Hello, I wonder if there's still anybody out there from this 6 year old post; I just found this while looking for a solution to my problem: synth turns on, orange display lit but no characters and no sound at all; battery has been replaced a few months ago and all was fine until recently; if I let it stay on for a few minutes it would come to life and work fine until turned off again, but now it won't work at all. Has anybody found if the problem was the power transformer, by any chance? Thanks!
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Re: Roland XP50 LCD Display Problems

Postby dgtl311 » 00:26, 12 February 2017

Hi Cesarsound,

I was hoping with all of your expertise on the Roland XP-50 that you could provide some advice:

I purchased a dead XP50 in hopes of bringing it back to life. It has the infamous blank display and I have replaced all of the caps on the main board. I noticed some leaky caps, but no damage to any of the traces or surrounding components that I could see under magnification. Replacing all of the main board caps didn't change anything. Voltages seem to check out as per the service manual, but I only checked the power supply and various points on the main and exp board. I should also note that it has a brand new CR2032 and the stop/play button or heartbeat is a solid red and does not blink. Pressing any buttons has no effect and there is no sound on any of the outputs when pressing the keys.

I really appreciate any advise you can offer.

Many Thanks,


UPDATE: I ended up finding 2 broken traces from IC12, which I repaired. It now has a heartbeat and I have audio output, although it it sounds like every patch has some extreme vibrato on it. Still nothing on the display, but at least I've made some progress. Is there a way to do a hard reset without using the display?
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Re: Roland XP50 LCD Display Problems

Postby CesarsoundOne » 14:32, 12 February 2017

A solution for no text on display (only orange light):
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.
-just remove the wire that is on pin # 3 of CN14 and solder this wire to the ground of PCB mainboard.

Some tips for the sound problems:
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.
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Re: Roland XP50 LCD Display Problems

Postby Subtox » 06:25, 5 March 2017

I too am having sound issues with my XP-50. I turned it on for the first time in years and got a hissing sound and a tiny bit of distorted audio when I pressed keys. At the advice of multiple forum threads I replaced all of the electrolytic capacitors on the mainboard. However now, there is no sound at all! Utter silence.

I should say I'm not an electronics expert and had a tough time with the job (although looking at my work I clearly got better as I went, haha). Here are the details of what I fixed, the mess I made, and the troubleshooting I've done. Any help as far as a next step would be appreciated.

For a few reasons, I replaced the SMD's with through-hole capacitors, by bending feet and soldering them to the pads. I was careful to buy the correct uF and voltage components. A couple of the originals were 6v and the supplier only had 6.3v, which I understand is OK.

Due to my lack of experience, and not helped by the old adhesive, I managed to lift a few pads from the board and break a few traces. I fixed these by either gluing the pads back down where still intact, or using wire strands to connect the capacitors back to the circuit further down the trace. I read the schematic carefully to make sure I was not bypassing any important components, and I did continuity tests in those areas afterward to make sure there was a signal.

I found that C932 was soldered in backward (it is paired with C931 but facing the opposite way, so as an oversight I soldered them in the same direction). I didn't notice any issues with the capacitor (pops, burns, etc.) so I corrected it and then did some continuity tests.

I also tried testing the capacitors themselves but I wasn't about to remove each of them from the board to do so, which I believe is necessary for a true test. The unit was turned off and unplugged, and I simply attached my multimeter leads to each side of the capacitor to see if I was getting an Ohms reading. In most cases it would flash a number like 1000-1500 and quickly return to 1, which I understand is what you want. Some capacitors stayed at a higher number though and I'm not sure if I was doing something wrong or those capacitors are bad.

Following the advice of CesarsoundOne's most recent post, i tested the voltage on pins 7 and 8 of IC19 and got 0 volts. Again, I could very well be doing something wrong. I powered on the unit, connected the negative lead of my multimeter to ground (one of the mainboard mounts with the screw holes), and the positive to pin 8, and then pin 7. For both of these, the multimeter quickly went back and forth between 0 and .01 volts. (As a troubleshooting measure I tested the battery and got 3 volts so I'm sure I have a good ground.)

I went into test mode on the unit and went through all the tests. All of the non-sound-related tests passed, however there was no sound for any of the sound tests. Also the after touch test failed, which was supposed to register a keypress but didn't. Although when I press keys in Perform mode the LEDs in the center section just below the LCD blink, so there is a signal coming from the keyboard.

I have of course tried multiple cables, both the headphone and L/R outputs, different channels on my mixer, plugging different instruments and mics into those same mixer channels, playing songs from a floppy disk in case it was a keyboard problem (no sound comes from sequenced files either), and I recorded a few measures on the sequencer and looked in Microscope Edit to make sure notes were being registered (they are).

Phew, thank you if you are still reading. If anyone has any suggestions on what I can try next I would be very grateful! I can't bring myself to trash this thing just yet. Especially since it was making *some* sound before I tinkered around in there, I'm pretty sure it's just something I did wrong and not a fried IC or something major.

EDIT: More info including close-up photos can be found at a previous thread I posted at Electronics Point.
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