Beginning a repair on a Roland XP-50

Hello, first time here, my names Phil.

The keyboard player in one of my bands asked if I would take a crack at repairing his buddies Roland XP-50 knowing that I’m a senior electronics technician at my day job. I also build my own tube amps and pedals for gigging so, he thought I might stand a chance at this repair.

If I remember correctly, there was no sound and the display was on the blink. I’ll be putting the synth on my bench tonight so, time to get rolling. My first line of action without knowing anything quite yet was to make a list of all electrolytic capacitors, order them up and replace. I figured that even if this is not the key component in the synths issues, its probably a damn good idea seeing that this synth is old and hasn’t been serviced as far as I know.

I surely would look forward to any input or advice on any aspect of this repair. It would be my first synth repair but I intend to give this a good shot and exhaust all of my efforts and resources.

Thank you all for having me aboard and I look forward to meeting some of you!

Best,
pjd3 (or Phil)

your on the right path, but first

no sound could be as simple as an dead op amp, but the display too means the power supply is probably out of spec.

Start with the power supply to see if all the voltages are there, and fix the areas where it isn’t.

before you start replacing electrolytic caps, tantatum caps are the majority of the problems in that vintage. replace them with something else. Tantalum caps either fail internally (short) with no external signs, or burst into flames. look for those two symptoms.

Once the power supply if fixed, then using the schematic as a reference, play a note to see what works, follow the audio signal from the output back to the audio generation chipset. You should be able to find a dead op amp in there somewhere if that’s the problem.

If the audio generation chipset is dead, consider the keyboard lawn furniture. If Syntauer needs parts for that model ask them if they want it for parts, but also let them know why.

The LCD is almost never repairable. when the fail they can only be replaced.
If Syntaur doesn’t have a replacement there is somebody on ebay selling new replacement LCD’s, so keep an eye out for that. If you find one seller for replacement LCD’s for another brand, email them as they might know who does, or can make one.

All of the problems you have mentioned are caused by the leaky caps, even the LCD. You have to replace all of those electrolytic caps on the main board, 27 of them. The only question is how bad acid damage to the tracks is, how corroded they are. If not big, then remove old caps, clean corrosion with alcohol, and solder new ones. I have fixed few XP50s and only one was so bad that I was not able to repair.

Ok so you need to get the display working first. There’s a common opamp that dies which reads the battery voltage and controls the display contrast. If you google XP50 contrast, there’s a video that shows the procedure of how to temporarily fix it. Most likely now the text shows and everything is fine but you will still get no sound because all the patches are garbage. Now you need to follow the procedure to reload the factory sounds. Now all the text will show and it will play sounds. If the battery is dead you will have to do this after every powerup. After you replace the battery everything will be normal but you will still get “battery low” until you replace the opamp. You will also need to recap it cause the silver metal capacitors on the mainboard are probably leaking.

I want to thank you all for what is obviously good advice and direction. It really does give me alot to go on to maybe fixing this synth.

Of course, checking to see that the proper voltages exist from the power supply but, considering the age of this synth, its sounding like a good idea to do the recommended cap replacements and that particular OP amp, plus, taking a good look at reloading the factory presets and getting a new battery in there if there isn’t already.
I’m feeling more than ready to start on this and I’ll surely be back to report findings as I go.

Thank you again for your invaluable information. It is indeed extremely helpful and confidence bolstering.

Best,
Phil Donovan