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Diodes on Yamaha Music keyboard query.
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Topic: Diodes on Yamaha Music keyboard query. (Read 1297 times)
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geobee
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Posts: 47
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Diodes on Yamaha Music keyboard query.
«
on:
April 20, 2018, 09:00:11 am »
Hi all, just wondering if anyone would know the purpose of the string of diodes, think they would be the old 1N914, on the key circuit strip. The diodes are off the carbon track switching pads. Any ideas would be great.
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Moshly
Regular Contributor
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What's wrong with this thing
Re: Diodes on Yamaha Music keyboard query.
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Reply #1 on:
April 20, 2018, 09:06:48 am »
Look up N-Key rollover
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capt bullshot
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Re: Diodes on Yamaha Music keyboard query.
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Reply #2 on:
April 20, 2018, 09:08:52 am »
My guess:
The diodes are used to decouple the key switches for a multiplexed scanner. If they weren't there, pressing multiple keys at the same time would short out some of the scanning lines and the keyboard scanner wouldn't work. Using the diodes enables the scanner to detect any number of simultanously pressed keys.
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Safety devices hinder evolution
LateLesley
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Re: Diodes on Yamaha Music keyboard query.
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Reply #3 on:
April 20, 2018, 09:16:24 am »
It'll be part of the keyboard matrix.
There's an example halfway down this page -
http://musicfromouterspace.com/analogsynth_new/OLDIESBUTGOODIES/CONTROLLERS/scanningmatrixkeyboard2.html
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Last Edit: April 20, 2018, 09:25:13 am by LateLesley
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geobee
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Re: Diodes on Yamaha Music keyboard query.
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Reply #4 on:
April 20, 2018, 09:23:16 am »
Many thanks to all, well explained. Looks like they are just performing a ''one way street'' from the keys.
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