Hi All. I had a Roland KR-3500 Digital Piano (similar to the KR-4500) that exhibited a Crackling audio sound on all keys. After reading somewhere about someone with a similar issue who had replaced all the Electrolytic caps I decided to also go down that route. (Spoiler : It worked !) After some basic troubleshooting I determined that it could be noise feeding thru from the Keyboard scanning since the Demo tunes played back undistorted and the Audio amp / speakers were fine ( Inserted an Audio signal into the rear Audio input). After extracting the main board from the shield, I replaced 7 Capacitors that ,although not looking damaged or bulging ,showed signs of leaking on the PCB area around them. I also repaired a damaged feed-thru and cleaned the board. After re-installing the board I checked that the issue was still there. I replaced a further 16 capacitors and finally the Audio was normal. There remain about 20 caps that I did not replace (and will probably have to in the future...but I'm not set up with proper fume extraction and the Solder fumes were getting to me so I decided to stop ;-) After measuring the removed components it was a wonder that the Keyboard worked at all ! All the 10 uf caps read under .1 uf ...I began to wonder if I had damaged then during my de-soldering, but after doing a test solder/de-solder operation on a scrap board I realized that they were really ALL BAD. In my case it was the 3.3uf caps that created this audio distortion ( C11,14,15,18,22,29,24 & 31) But the bottom line is I would suggest just replace all Electrolytes on that board ( Main Board Assy 7627590000 in my case). ( Qty. 19 10uf/16v, Qty. 4 10uf/25v, Qty. 8 3.3uf/50v note: I used 4.7uf to replace these 8 with no adverse effects) Hope this helps someone. P.S. to open the piano there are 6 screws, 3 on each side underneath that once removed allow the top to be lifted like a car hood. Also there is a troubleshooting mode that can be accessed by pressing "Advance/Basic" and "Sync Stop" buttons while turning on the unit. Select the 14 tests with the "inc" and "dec" keys.
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Hi All
These seem to be quite popular , but first time i'm attempting to repair one .
Customer mentioned a crackling coming through when using an external mic to record via XLR ports .
What i have experienced is the unit being tap sensitive & crackling even without playback .
Anyone have experience of working on these units ?... -
Need schematic for Williams Overture digital piano.07-19-2022, 01:11 PM -
Good day folks. Today, I came across something kinda special, which I haven't worked on before: a Roland RD100 electric piano. It was just sitting there in the shop covered in dust, no doubt having been ravaged and then abandoned by my oh-so-skilled co-worker. I actually remember seeing him struggling with this thing and I recall briefly witnessing the problem too: some of the notes play distorted. I'll try plugging it myself and maybe do some captures for you to hear for yourselves, but let's just say it sounds....bad.
I haven't actually dug into it myself yet, so this is mostly... -
Hi,
I received this Yamaha P105 digital piano completed dead - no power and no standby lights. Pressing the power button does nothing.
I have checked the power adapter has 15V output to the piano. I opened up the keyboard, and did some basic checks, and there is 15V input to the power supply board. But that is apparently no power feed into the main board that connects to the power switch button.
Attached is the pictures of the PCBs, and the service manual I downloaded.
I need help to get guide me where to start tracing for problem(s).
Thank... -
Hi All,
I have a used Clavinova CVP 209 that isn't playing any sound from the keys or memory, neither on headphones nor line out. The speakers work OK from line in, and the rest of the lights and screen seem to work just fine.
I have tried doing a factory reset by holding down the top key and turning it on, but that doesn't help. I did the RAM/ROM checks and they're OK. I checked the volume potentiometer and it seems OK (works with line in audio). I'm thinking it might be faulty DACs from the synth board (IC 28 and 29: ) or op amps. Not sure how to narrow it down more. I've...