key board repair question

[Guest Entity]

I am in the act of buying an older synth that has 2 keys that do not work.

 

I am hoping to buy this machine and repair it.

 

I am not an expert but I know haw to solder.

 

Also, I am thinking that if the keys do not work the midi signals should still be able to get the machine to play the sounds, just not when I hit the key.

 

 

OK, so questions

 

1) Is it possible that the 2 keys will not work and still play via midi?

 

2) If only 2 keys are not working I am expecting that there must be a problem with the 2 individual keys not contacting their individual signals. If this is the case that means that under the keys there shoud be a button that is not getting it's signal.

Will this be a repair requiring special parts or could it be a simple broken solder?

 

I know that my questions are vauge, but any info will be a big help.

 

Please respond, this deal will be made soon and I really hope to not be setting myself up for lots of troubles.

 

thank you

[Guest DeeperNETWERK]

They should work if triggered by another midi device, yes.

[Guest PortaMento]

It depends on how it works when you press a key. If the key hits a closed switch, that switch could be worn out, and then you'll need a new one, which is a "special part".

Some synths use very simple open switches, which are just two metal strips. When the key hits the top strip, it bends and touches the other strip, creating a contact. These switches will not work if they become dirty, but they are easy to clean.

But it could be a broken solder as well, I guess. You won't know for sure, until you see the inside.

But in any case, you should be able to trigger the key by midi.

[Feathers]

One of the keys went dead on my old GEM-S3 Turbo workstation.

I opened up the machine and underneath the keys there are diodes on a circuit board. These diodes are usually very small glass/clear cased cylinders soldered to the circuit port. They are used by the keyboard scanning circuit and it could be one of these that needs replacing. On my GEM it was a very simple matter to find the diode since it was directly inline with the key position. A diode is a very inexpensive component. Perhaps you can find someone with knowledge of electronics?

 

It could of course be a switch/contact problem as Portamento said. WD40 is good for cleaning/lubricating electrical contacts. I even spray it on the gold edge connectors of my PC parts (it reduces wear and tear and cleans the surface as well).

 

Feathers.