Weird D-50 key?

[Alex E]

Not sure what's going on here, but there's a sharp key on my D-50 (on the top octave) that basically makes that particular octave monophonic when you hold it down. So, in other words, I can't play chords with that key depressed. Weird.

The white key next to it does the same thing. Any ideas?
I'm gonna replace the battery soon, but I don't think that's going to help anything.

[pflosi]

D50 keybeds are a nightmare. A mate of mine has a D50 and we've had almost everything fail in the top octave - velocity, aftertouch, etc. It's probably just a bit dirty.

OTOH, does it happen on all patches? If not make sure no keyboard split is enabled...

[Alex E]

Yeah, it happens on all the patches... I'll take a look inside when I replace the battery.

[Pro5]

I doubt it's the battery. Was it doing it when you got it or just started?

First thing unplug all connections check for corrosion, then replug them - sometimes sorts things. Make sure they are pushed on properly including the white plastic ribbon cable on the underside that connects the two halves of keybed.

It could be a damaged trace or wire for that octave (a short or the opposite) - you'll need to inspect the pcb under the keys (that the rubber cups go on) and use a multimeter to test each trace has continuity as it should and no shorts.

After that check the board fixed under the keybed (the dynascan) the memory chips on these can go, and cause all kinds of weird problems. A note on up there could feasibly block all other note on events if there's a problem on that board. It's a weird set up but removed some of the logic from the mainboard, maybe for easier replacement of just that board. Can't recall if the gate array chip is on that board or on the mainboard but that would be my final thing to check.

You can troubleshoot by plugging in the different halfs of keybed hi/lo - swap em over, you'll see what i mean when in - then see if the problem continues but this time lower down - if so its unlikely to be the keybed but the dynascan or gate array (or both).

[Bitexion]

I have one key on mine that always plays louder than the others. Probably something to do with the velocity sensor, it always plays at 127 velocity. Not a huge issue since it's one of the upper black keys.

[Pro5]

That just needs the contact cleaning. A single note with max velocity means it's not seeing the rear cup hitting the contact so assumes instant/fast key press = max velocity.

Just need to rub the contact and the inside of the rubber cup with a dry cotton bud (or Q-tip depending on your nationality) - synth fixed.

info: On these synths and many Rolands under each key are *2* rubber contacts front/rear - the rear one is lower than the front one so it hits it's contact on the keybed PCB first. Then the front one hits (The note on/off trigger) the time diff between those hitting = the velocity rate. at full rate they both hit at pretty much the same time (very quickly). When the rear contact is dusty/dirty it's never even seen to be hitting the contact at all so when the key on event comes it combines both and assumes it was very quick = max velocity.

It's a very simple fix - the only problem is the D-50 is a nightmare to dismantle esp if you are new to opening synths up. You'll need to remove the mainboard, some connectors, then the keybed assembly - then the key springs and keys for at least that strip of contacts up until you find an 'end' and then you can peel back the rubber cups (gently dont break the little rubber tabs) clean the contacts and replace gently and ensure the bits are all pushed back nice. When you take the springs off put black key springs in a seperate pile as they are longer than the front key ones (or your black key may sit high if you put a short spring on it)

To remove the keys prise back the clear plastic strips on the underside of the keybed that stop the keys being pulled forward - with a thin small screwdriver - don't need to pull them off (if you do you can glue them back on or double sided tape as they are to start)

[Bitexion]

Having never opened a synthesizer in my life, and being a colossal clutz when it comes to breaking all sorts of things, I think I'll just leave it as it is.

I'll probably end up with all the keys in a mess on the table and not being able to put them back inside again.