Hello all!
I’m repairing a Korg Krome 88 that was given to me for free due to key contact problems.
After trying to use new rubber contact strips I discovered that many of the contact points on the boards themselves were worn, so I ordered a replacement set of boards. After installation I replaced the contact strips, keys, ect., and… nothing. No sound at all from any key.
I began systematic testing in an attempt to find the problem. First, I plugged in my headphones and turned the volume knob up and down. I can still hear the (very) faint hiss of white noise that changes when I turn the volume knob, which suggests that current is still being conveyed across the audio outputs
Secondly, I checked the velocity meter on the display. Nothing there either, for any key. That tells me that the motherboard is not receiving a signal from the keybed itself.
I then checked the 16-part cable that connects to the new contact boards. All channels are conducting properly.
As I looked at the new boards, I noticed a dark green substance spread over the contact points which is not present in any amount on the old boards. Is this merely a conductive compound, or is it a manufacturing protectant that should be removed?
Also, while removing the small ribbon cables that connect the boards together I noticed that the old boards have FPC connectors that are slightly more bulky than the new ones.
Is this possibly the issue, or is there something simple which I am overlooking (which is entirely possible!)?
Thank you in advance for your advice!