Just joined the forum and want to say hello. My name is Mark Wybierala and I've been a professional luthier for nearly twenty years. I get keyboards in for repairs a few times a year and generally have been lucky with being able to repair the usual dead key/touch sensitivity problems along with replacing broken hardware. But I sometimes could use some help. I have a background in electronics in the military so I know a little -- enough to get myself in trouble. I'm looking for recommendations for a tutorial on understanding how the switching matrix of the keyboard functions. On occasion, I come across multiple dead keys and being able to understand the commonality of the keys would save me a lot of time. Right now I have a Kurtzweil that has an intermittent problem of multiple dead keys that is intermittent and there is no evidence of any problem on the key contact circuit board.
Hello Friends
- Thread starter Mark Wybierala
- Start date
happyrat1
Destroyer of Eardrums!!!
It's often possible and very useful to find a service manual online for either the board you are working on or an earlier, discontinued model with similar specs.
As for the keyboard matrix, you should be able to find youtube and google tutorials on basic multiplexing designs that might help you out.
Which model Kurzweil are we talking about here?
Gary
As for the keyboard matrix, you should be able to find youtube and google tutorials on basic multiplexing designs that might help you out.
Which model Kurzweil are we talking about here?
Gary
happyrat1
Destroyer of Eardrums!!!
Here's a simple youtube search about keyboard multiplexers.
https://www.youtube.com/results?search_query=keyboard+multiplexing+circuits
While it's mainly about computer keyboards the principles are not all that different from musical keyboards.
EDIT >>> Here's a second search specifying musical keyboards.
https://www.youtube.com/results?search_query=musical+keyboard+multiplexing+circuits
Gary
https://www.youtube.com/results?search_query=keyboard+multiplexing+circuits
While it's mainly about computer keyboards the principles are not all that different from musical keyboards.
EDIT >>> Here's a second search specifying musical keyboards.
https://www.youtube.com/results?search_query=musical+keyboard+multiplexing+circuits
Gary
This is a K2000. Eflat4, B4, and G5 didn't work when it came in. When I looked inside, the right hand ribbon cable looked like it wasn't seated properly -- didn't lock properly either. I secured the ribbon cables with a small drop of hot glue, and the problem went away. This morning, I did a last check of the keyboard before I called the customer and there was a touch sensitivity problem on C1 so I opened it up, cleaned the contact pad and put it back together. At that time, the Eflat4, G4 (a new problem), and the G5 ceased working so I pulled the contact board and inspected it. Its totally clean with no obvious typical problems like corrosion or cold solder joints. I spray cleaned the ribbon connectors, reassembled, and now I'm back to the original three dead keys. It might be the ribbon cable itself but manipulating the cable at the connections doesn't yield any help.
Like I said in my introduction, I get lucky often but out of a dozen or two keyboards that I've repaired, I've yet to come across one that didn't have a physical or contamination problem causing dead keys. I'm sure it happens where there are weird issues. I'm not giving up yet but I don't charge for services if I don't fix the problem -- client isn't responsible for my learning curve. I don't advertise that I repair keys but one sneaks into the shop every now and then.
Like I said in my introduction, I get lucky often but out of a dozen or two keyboards that I've repaired, I've yet to come across one that didn't have a physical or contamination problem causing dead keys. I'm sure it happens where there are weird issues. I'm not giving up yet but I don't charge for services if I don't fix the problem -- client isn't responsible for my learning curve. I don't advertise that I repair keys but one sneaks into the shop every now and then.
Welcome Mark.
When it comes to keyboards, I know a little about using them, and bugger all about fixing them. Your voice will be welcome here along with the others who have good mechanical/electronic skills!
When it comes to keyboards, I know a little about using them, and bugger all about fixing them. Your voice will be welcome here along with the others who have good mechanical/electronic skills!
happyrat1
Destroyer of Eardrums!!!
First hit on Google. K2000 service manual.
http://www.synfo.nl/servicemanuals/Kurzweil/K2000_K2000R_SERVICE_MANUAL.pdf
133 page service manual complete with schematics.
Probably a cold solder joint you missed anyway.
Check the cables with a DVOM too.
If you have a decent scope or a logic probe at your disposal you can try some signal tracing.
Intermittents can be a bitch to troubleshoot.
Gary
http://www.synfo.nl/servicemanuals/Kurzweil/K2000_K2000R_SERVICE_MANUAL.pdf
133 page service manual complete with schematics.
Probably a cold solder joint you missed anyway.
Check the cables with a DVOM too.
If you have a decent scope or a logic probe at your disposal you can try some signal tracing.
Intermittents can be a bitch to troubleshoot.
Gary
Wow. What a great welcome. This will certainly be my place to go for help. I did not expect a schematic let alone a full service manual. Thank you Happy Rat. Most google searches for schematics and manuals lead to scams so I often don't bother any more. Thanks again to all for the welcome and assistance
I am a competent luthier. My forte is fretwork and I build one-off custom guitars for clients and other stringed instruments on the fringes of normalcy, I'm happy to be of assistance and I enjoy sharing what I've learned over the years. I like teaching what I know and I keep no secrets. I believe that my email address is available on my profile here. Send me an email direct if you think I can be of any assistance and also send me an email to accompany any friend requests on facebook so I know who you are. I do luthery as a passion because there certainly isn't any money in it unless you leave victims in your wake.
Thanks again
Mark
I am a competent luthier. My forte is fretwork and I build one-off custom guitars for clients and other stringed instruments on the fringes of normalcy, I'm happy to be of assistance and I enjoy sharing what I've learned over the years. I like teaching what I know and I keep no secrets. I believe that my email address is available on my profile here. Send me an email direct if you think I can be of any assistance and also send me an email to accompany any friend requests on facebook so I know who you are. I do luthery as a passion because there certainly isn't any money in it unless you leave victims in your wake.
Thanks again
Mark
happyrat1
Destroyer of Eardrums!!!
You're welcome Mark.
Like you, I know enough electronics engineering to get myself into trouble
We don't keep many secrets around here either. Everyone on these forums tries to help each other out as best we can.
Gary
Like you, I know enough electronics engineering to get myself into trouble
We don't keep many secrets around here either. Everyone on these forums tries to help each other out as best we can.
Gary
Rayblewit
Love Music / Love Life
Hi Mark
Welcome to the forums.
I did not know what a Luthier did. Never heard of that word before.
I thought you belonged to the Lutheran church . . Lol
Its ok . . I looked it up and now I know.
"No strings attached" . . Chuckles
I am becoming more and more knowledgeable everyday here at this forum.
Collector of information -ray
Welcome to the forums.
I did not know what a Luthier did. Never heard of that word before.
I thought you belonged to the Lutheran church . . Lol
Its ok . . I looked it up and now I know.
"No strings attached" . . Chuckles
I am becoming more and more knowledgeable everyday here at this forum.
Collector of information -ray