Trouble with the circuit board of my Synthesizer keys

Thread Starter

hide24

Joined Jul 9, 2019
83
Hello everyone,

I own a roland D-50 synthesizer which some of the keys don't produce sound.
I tried to clean the strip rubber contacts with alcohol, but without success.

The funny thing is that the synthesizer itself it's in mint condition, and the bad keys follow a "pattern" ( I mean are the 3rd of each line as you can see in the picture)
I attach a picture which you can see the wrong keys with tape .
What could be the cause ?

The things are tried are:
1-clean contacts
2-try another rubber note in the place of the bad note.
3-Check diodes (which seems fine)

Thank you very much!
 

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Alec_t

Joined Sep 17, 2013
12,808
The keys are almost certainly arranged as a scanned matrix of rows and columns. The affected keys (all are 8 pads apart) likely connect in common to a particular row/column which isn't making a good connection with the scanning IC. I'd be looking for an edge connector problem, or an IC fault.
 

Thread Starter

hide24

Joined Jul 9, 2019
83
Thank you very much!
Today I tried to clean with spray contact cleaner all the connections. Also unplug and plug again the cables but with no success.
What does it mean a "locking lever involved"?
Could be the ribbon flat cable damaged?
 

Thread Starter

hide24

Joined Jul 9, 2019
83
Today I've been checking and, seems this connector don't use levers. I will try to buy a ribbon cable if I can find.
There are two cable connectos which from the key scan board to the other half of the keyboard. Those are checked and seems work fine.
 
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