Roland XP50 LCD Display Problems

Forum for JD, JV, XP and XV synthesizers from 1990's
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Thanks for replying. That was quick!

Now, which one is better, 1uF or .1uF?

And do you still have the schematic? If so, please email to me at mustang-83 at ca dot rr dot com

Thanks again!
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Hi Cesarsound,

I saw someone mention replacing C901, C902, and C65 to fix the LCD display problem. Does this also help or should I replace only C83 and C63?

Also I'm kinda confused because someone said he replaced all these caps (C901, C902, C65, C83, and C63) and still the problem remained. It seems that the problem was finally fixed by removing the wire on pin 3 of CN14 and soldering it to PCB ground. So is this the real solution that works or does replacing the caps also work?

Lastly, what is the function of the capacitors C931 and C932? Are these capacitors in the signal path?

Thank you so much for your help!
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

Besides the replacement of caps, it is necessary als to redo the PCB wiring. Please see the pictures and the message from user "Obsolet" in this subject:

"Cheers Mate! You saved another XP-50's display :)
A friend helped me with the repair, he replaced C63 & C83 and wired pin #2 of IC17 with R74 left and R73 with R74 (right to left). Now display is working perfect again, contrast can be set from 1 to 10 as well!

Thank you very much again for the detailed instruction!

Thumbs up!

Best greetings from Germany & a happy XP-50 owner!
Obsolet"

Posts: 2
Joined: Sun Sep 04, 2011 12:41 pm
Private message
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Hi Cesarsound,

I don't see any corrosion or broken traces in mine. I think my problem was that I was not using my XP-50 for a long time. As you know, electrolytic capacitors can become weak or they may even stop working if no electrical current passes through them for a long time. So one day, when I turned on my XP-50, there was no more LCD display. Sometimes when I turned it on there was a display but it would fade away and disappear after 5 minutes. So I left my XP-50 turned on for 3 days, and after that, the LCD display began to work again and did not disappear anymore.

However, because of what happened, I think that some capacitors are already weak, so I want to replace them. Considering that there are no broken traces in my board, I don't really need to do the rewiring of IC17 pin #2 with R74 left and R73 with R74 right to left. I only need to replace some capacitors. Am I correct? If so, which capacitors do I need to replace? Do I need to replace C83 and C63? How about C901, C902, and C65, do I need to replace these also? Or what about removing the wire on pin 3 of CN14 and soldering it to PCB ground? Should I do that also, just to be sure?

Although my LCD display is fine as of now, I just want to prevent it from going bad again. If the XP-50 has a design flaw, what do you suggest to correct it so that this problem will never happen again?

I really appreciate your help. Thank you so much for staying with me on this thread.
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

My XP50 had the same symtpoms of yours, when I turned on my XP-50, there was no more LCD display. Sometimes when I turned it on there was a display but it would fade away and disappear after 5 minutes. But one day the text on display disappeared at all and not returned anymore. The solution for this problem was replacing the mentioned caps and redoing the mentioned PCB wirings.

To check if the PCB wiring is open or not you should use a multimeter in low resistance (x1) range, it must be almost 0 (zero) ohm if ok.

Cesarsound.
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Cesarsound wrote:My XP50 had the same symtpoms of yours, when I turned on my XP-50, there was no more LCD display. Sometimes when I turned it on there was a display but it would fade away and disappear after 5 minutes. But one day the text on display disappeared at all and not returned anymore. The solution for this problem was replacing the mentioned caps and redoing the mentioned PCB wirings.
I just want to be sure, for my particular case, which wiring are you referring to:

This: "Rewire IC17 pin #2 with R74 left and R73 with R74 (right to left)."
Or this: "Remove the wire on pin #3 of CN14 and solder it to PCB ground."
Or should I do both of them?
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

Fisrtly I adopted the solution of "Remove the wire on pin #3 of CN14 and solder it to PCB ground."
But with this solution it is not possible to adjust the LCD contrast. So I decided to investigate more deeply the problem and ended up discovering the problems with caps and open PCB wiring.
Then I undid the first solution and did the second one: "Rewire IC17 pin #2 with R74 left and R73 with R74 (right to left)." This is a definitive solution because you will be able to adjust the LCD contrast as usual.
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Thanks, Cesarsound! It is clear to me now. :-)

Regarding the capacitor replacements, someone else suggested to replace C901, C902, and C65. Do you think that is necessary, or should I replace only C83 and C63?
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

C65 is related to auto-reset circuit when power-on.
C901 is related to delay cicuit that mutes the outputs when power-on to avoid pops.
C902 is related to the power supply filtering of the DA converters.

So unless you have problems in these areas, you don't need to replace these caps.
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Wow, thanks a lot, Cesarsound! You really have deep knowledge about the XP-50's circuit.

Based on your advice to Moripi in this thread, I'm also thinking of replacing the capacitors C931 and C932, and the ones in the analog signal path like C6, C7, C8, C11, C174, C175, C86, and C90 even if they are not yet failing. Considering the age of my XP-50, perhaps these capacitors are no longer performing at their best. So I will replace them with good quality, low impedance Panasonic FC capacitors. Do you think this is a good idea? Will this improve the sound quality of my XP-50? Well, I hope you'll say yes, but even if you say no, as long as it will not make my XP-50 sound bad or cause any degradation in sound quality, I will do it just to prolong the life of my XP-50. What do you think?

By the way, what is the function of the capacitors C931 and C932?
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

C931 and C932: both 10uF are the power supply decoupling for the +15v / -15v lines, that supply the analog section (Op Amps).

It is recommended to replace the capacitors after 5 years old because they become dry and consequently reduce the capacitance values. If the caps are on audio path, this will cause reduction on low frequency response, reduction on output volume or even no audio at all. I some cases it cause noises (hiss, cracks) on outputs. Other problem is when it enters in short circuit, in this case it will leak and corrode the pcb.

The low impedance Panasonic FC capacitors are very good caps for audio, you will get a better audio specially in low and high frequencies. Only for your information, the Motif XS uses similar caps on analog audio path and outputs, so here is one secret of its great sound.

If you have the ability, replace them. But it is at your risck, because the PCB wirings are very very weak and can be damaged easily with high temperature solders, in some cases will render the total ruination of mainboard.
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Cesarsound wrote:The low impedance Panasonic FC capacitors are very good caps for audio, you will get a better audio specially in low and high frequencies. Only for your information, the Motif XS uses similar caps on analog audio path and outputs, so here is one secret of its great sound.
That's really good to know! Yeah, the recent capacitors from Panasonic (FC and FM), Nichicon (HE and HN), and Rubycon (ZA and ZL) are great. So much has advanced in capacitor manufacturing technology since the time the XP-50 came out. IMHO the capacitors now are much better.

Thank you so much, Cesarsound! I really appreciate your help and your generosity in sharing your knowledge. I'm so glad I found this thread and all my questions have been answered!
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Hi Cesarsound, my capacitor order has arrived and I'm now ready to start working on the mainboard. But first I have a few more questions:

1. Is it alright for the battery to be installed or do I have to remove it when working on the PCB?

2. Are all those SMD capacitors such as C83, C63, C86, C90 temperature-rated for 85 degrees Centigrade? I'm just curious because there is no temperature marking on them.

3. How do you safely remove and put back the white flat ribbon cable connecting the boards? Do you apply something like a conductive lubricant? I'm worried that if I remove the cable I might have much difficulty putting it back. Seems like the connector/slot is tight, and the cable looks so flimsy that it will bend and be hard to insert back in. So I'm thinking of using some Deoxit Gold G5 spray http://www.mcmelectronics.com/product/2 ... =220223251 to lubricate it. By the way, this product also claims to enhance the connection's conductivity. Would you advise to use this?

Thanks!
Cesarsound
Posts: 369
Joined: 04:50, 24 December 2005
Location: SP - Brazil

Re: Roland XP50 LCD Display Problems

Post by Cesarsound »

Hi mtl777,

1. Is it alright for the battery to be installed or do I have to remove it when working on the PCB?

R: you don't need to remove the batery, but if you do it, you will need to backup your user patches / performances before on floppy disk (disket).

2. Are all those SMD capacitors such as C83, C63, C86, C90 temperature-rated for 85 degrees Centigrade? I'm just curious because there is no temperature marking on them.

R: Yes, in general all caps are rated to 85 dgC to endure the soldering process and normal operation.

3. How do you safely remove and put back the white flat ribbon cable connecting the boards? Do you apply something like a conductive lubricant? I'm worried that if I remove the cable I might have much difficulty putting it back. Seems like the connector/slot is tight, and the cable looks so flimsy that it will bend and be hard to insert back in. So I'm thinking of using some Deoxit Gold G5 spray http://www.mcmelectronics.com/product/2 ... =220223251 to lubricate it. By the way, this product also claims to enhance the connection's conductivity. Would you advise to use this?

R: In my XP I have not removed that white flat ribbon, due to your exactly concern. But I have removed others flat ribbon from others electronics apparatus and I used a small dip of WD lube oil to facilitate the re-inserction. This Deoxit Gold G5 spray should works fine for this operation too.

Cesarsound.
mtl777
Posts: 20
Joined: 23:45, 1 December 2010

Re: Roland XP50 LCD Display Problems

Post by mtl777 »

Thanks, Cesarsound!

Due to 0.1uF being out of stock, it turns out that I only have either 1uF or 0.47uF to replace the original 0.1uF for C83 and C63 (I previously mentioned that these caps are 0.1uF in my XP-50, not 1uF as they are in yours). If I use 1uF to replace those caps, will it possibly have the side effect of making the LCD display brighter (but not necessarily clearer)? I'm just concerned that a brighter display might shorten the life of the LCD display. Therefore, if a higher capacitance than the original will cause the brightening side effect, should I use 0.47uF instead to stay as close as I can to the original value of 0.1uF?

Lastly, now that I'm doing an overhaul of my XP-50, I thought I might as well replace all the caps in the power supply. They are just a few caps anyway. I will replace them with the same values but better quality (Panasonic and Nichicon) and higher temperature rating of 105 deg.C. Do you have any words of caution or advice regarding this?
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