Roland XP50 LCD Display Problems

[Maxx2206]

Hi,

while these sounded like very good tipps to continue searching for a fix for my xp50, they turned out to be just more deadends...
after replacing all caps on the mainboard i was apparently able to fix my strange unstable cold boot issues (had to "preheat" the synth by turning it on and not touching it for 10-15 minutes or it would simply freeze) and also the lcd issues by grounding pin3, i still have the very low volume issue bugging me.

i've spent quite some time cleaning and carefully checking the mainboard for obvious faults. i measured voltages on Q13 and IC19 pins 7 and 8 (collector of Q13 has +15V, Output on the emitter is around 3-3.5V, and so are the voltages on pins 7 and 8 of the DAC).
Q14 and its corresponding parts on the backside arent populated at all so no point in doing any measurements there...

the multimeter reads about -7.5v on R132 next to C901.

i have no distortion or other bad sounds, its just an extremely low volume, barely hearable with a headset.. and only very quiet when i connect external speakers.
any ideas what i could check next or maybe replace as a precaution?
i just try to avoid soldering if not really necessary... the pcb is so old, its extremely fragile and vulnerable to heat is seems... the smd pads show a very high risk of lifting up as soon as i touch them with the solder tip even though im fairly experienced in soldering (nonetheless the repair attempt on my trusty old xp50 made me gain even more experience in smd reworking and working with flux gel and smd paste ;) ).

any help is highly appreciated... im so close of having it finally fixed with all other issues being gone so far, just the volume remains...

[RolandoKix]

Analyzing the picures I can see that the pcb wiring on second pin of IC17 and R74 was damaged (cut). This was caused due to leakage of electr. caps C63 and C83, as the internal electrolyte is acid and corrode the pcb wiring. Is the same case that occured with my XP.
Try to re-do the electrical connection between the pin #2 of IC17 and R74 (lef side), with a fine wire, low power solder and a magnifying glass.
Note: the left side of R74 must be connected to the right side of R73.

G.Luck.

Hello Cesarsound and other board members. I have a similar problem with my new XP-50. My R74 is totally disintegrated. If I buy a new resistor, I am unsure where to connect the other end (besides the one that connects to IC17 and R73). The schematic seems to show it connects to R72 and R82. I do not see how that should be wired though, because R82 doesn't seem to even exist on the PCB. Any ideas?

Another problem: the L/mono output works and the R/stereo output works, but when I connect the stereo/R output at the same time, the L/mono output doesn't work any more. If I remove the stereo/R output, the mono output works again. Is this a bad capacitor issue, or some other component has failed?

Thanks!

[repairman]

Hi...I replaced all of them with tantalum capacitors five years ago and no problems...everything works.

[knicknac]

Hi there. So I replaced all the capacitors to fix a blank screen problem. Problem remained. Sound is fine. I can use the work around of cutting wire 3 of CN14 and connecting it to earth - the display comes back but with no control over contrast of course. So to try and get control over contrast, I checked the connection between R73 and R74 which seemed good. I then tried for continuity between pin 7 of IC17 and R73: that seemed a bit dodgy so I rewired it and reconnected wire 3 of CN14. The result is that the display now works but it's now stuck on a fairly high contrast with no control over it. Any ideas?

[hmac]

Hello all- happy to be here. I recently acquired an XP-50 from an old friend and it had the low volume issue many have expressed here- though my display was actually fine, I had low volume output from both channels(both headphone out and line outs).

I've started the process of replacing all capacitors on the mainboard (painstaking as many of you know), and accidentally ripped both pads off C86 😫.

I am an amateur solderer, and an even more amateur electrical tech, so searching the schematic has yielded me very little with respect to actionable intelligence. I assume I'll have to jump the capacitor somehow, and I'm hoping someone here might have some good advice to share as I have no idea where I need to connect the jumpers.

Thank you ever so much in advance!

[MatrixRat]

The space between IC24 and R88 looks like a good place to glue an SMD Tantalum cap, upside down. Suggest epoxy and use some fine ~320 grit emery to rough up the area a little, enough to de-glaze the surface. Think carefully about orientation before you stick it down.