Hey folks, I have this old Korg 88-note stage piano.
A couple of the notes are "always" loud.
I assumed there would be a problem with the rubber actuators, but having taken it apart today, they're 100% perfect.
The electronics look pretty simple, two sensors for the first and second "strikes" from the rubber actuator, then these go thru 2 resistors (1 each) by the looks of it.
Am just about to measure the resistors to see if any have an anomalous readings...
But generally, I'm a bit mystified... everything looks 100% visually, no signs of burning or excessive wear in anything.
From general searching online, I've not seen any advice or tutorials except for the usual stuff relating to worn or perished rubber actuators. What are the chances a resistor could be blown...? pretty slim I would have thought... it's not actually had very much use to be honest and always stored in reasonably dry conditions.
Anyone know about these things, had a similar situation or can maybe offer some tips?
Korg SP-200 digital piano LOUD notes
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- KVRist
- 259 posts since 31 Oct, 2021
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- KVRist
- Topic Starter
- 259 posts since 31 Oct, 2021
well... interesting developments...
no problem with the resistors, but I thought I'd try something obvious that I didn't try before:
I swapped one of the actuator strips for another... lo and behold, the "loud" note has now moved.
Despite all visual indications that the rubber is perfect, it really is the actuator that needs replacing!
Must be something happening at a near-microscopic level.
For all who stumble this way in future, take heed regarding rubber actuator strips... it may not look like there's anything wrong with it, but it still needs replacing!
no problem with the resistors, but I thought I'd try something obvious that I didn't try before:
I swapped one of the actuator strips for another... lo and behold, the "loud" note has now moved.
Despite all visual indications that the rubber is perfect, it really is the actuator that needs replacing!
Must be something happening at a near-microscopic level.
For all who stumble this way in future, take heed regarding rubber actuator strips... it may not look like there's anything wrong with it, but it still needs replacing!
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- KVRist
- Topic Starter
- 259 posts since 31 Oct, 2021
Last word: silly me, it's a carbon contact in the rubber actuator! So... for whatever reason, it's no longer conductive, and no, the there wouldn't necessarily be any visual indication.
In truth, it's 4 "sensors", i.e. two pairs - the carbon contact in the rubber actuator makes a contact between two sensors to carry a current.
In truth, it's 4 "sensors", i.e. two pairs - the carbon contact in the rubber actuator makes a contact between two sensors to carry a current.
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- KVRAF
- 7120 posts since 22 Jan, 2005 from Sweden
Another approach is to compare velocity out from loud notes with others.
- hit similar strength ten times each key and look in daw how velocity compares
- so identifying which notes deviate from most
- so focus on fixing those
I refurbished D50 keybed a couple of times when some keys started to behave.
- so don't go by looks
- clean with some antioxidation contact spray, and rub with cotton tops
- on circuit board
- and conducting rubber too
Yet another approach is to look for settings in digital piano itself.
- my Kawai MP7SE you can set each keys level, filtering, pitch tuning and whatnot
- so if some keys produce serious louder notes you can fix that
Pretty sure Korg has that too to a degree.
- hit similar strength ten times each key and look in daw how velocity compares
- so identifying which notes deviate from most
- so focus on fixing those
I refurbished D50 keybed a couple of times when some keys started to behave.
- so don't go by looks
- clean with some antioxidation contact spray, and rub with cotton tops
- on circuit board
- and conducting rubber too
Yet another approach is to look for settings in digital piano itself.
- my Kawai MP7SE you can set each keys level, filtering, pitch tuning and whatnot
- so if some keys produce serious louder notes you can fix that
Pretty sure Korg has that too to a degree.