[KL] K2500RS Analog output distortion issue

[[e-mail] [KurzList]]

Friends,

My K2500RS has begun outputting distorted audio. It is not constant, but repeating (ie: if you strike a key on a controller repeatedly, every third strike out of four distorts.) I did a hard reset, ran the full series of tests (all passed) tried an imported demo sequence, cable swaps, changed all outputs--no change in the symptom. I thought I'd see if anyone else had experienced this before I pull it from the rack and pop the hood. The only other thing I've found is that I can no longer access the internal hard drive (I have a spare I can swap.) All the installed ROM (orchestral/contemporary/piano) works fine (albeit with the distortion.)

Any ideas?

~Mark

[Caleb Garner [e-mail] [KurzList]]

I don’t know the Kurzweil products intimately but i’ve owned and read about enough other products (Juno 106 and others).. it sounds like a “voice chip” problem though with K2500 having 48 voices I imagine they have something more sophisticated than imagining 48 actual independent voice chips to swap out. However it’s managed by a K2500, I bet it’s still in that realm of where the voices are managed / sound distributed.

I wonder too about multi timbral stuff too.. does the “every third” effect EVERY note regardless of which instrument is playing or only resides on one.. i’m guessing it doesn’t matter, but it might help isolate the issue?

Sincerely,
Caleb Garner / 615-818-8483

Post by ***@yahoo.com [KurzList]
Friends,
My K2500RS has begun outputting distorted audio. It is not constant, but repeating (ie: if you strike a key on a controller repeatedly, every third strike out of four distorts.) I did a hard reset, ran the full series of tests (all passed) tried an imported demo sequence, cable swaps, changed all outputs--no change in the symptom. I thought I'd see if anyone else had experienced this before I pull it from the rack and pop the hood. The only other thing I've found is that I can no longer access the internal hard drive (I have a spare I can swap.) All the installed ROM (orchestral/contemporary/piano) works fine (albeit with the distortion.)
Any ideas?
~Mark

[[e-mail] [KurzList]]

Caleb,

It is global, with the caveat that on a handful of patches (no particular category) it is total drop out every few strikes instead of distortion.

Thanks for your feedback. My first thought was multi-timbral as well, though it doesn't SEEM to be timbre-related.

~Mark

[derrick simpson [e-mail] [KurzList]]

My experience with my 2500 has been that it is the Effect board causing the
problem...You can confirm this by using only the Master outputs and turning
off the Effects unit.

Post by ***@yahoo.com [KurzList]
Caleb,
It is global, with the caveat that on a handful of patches (no particular
category) it is total drop out every few strikes instead of distortion.
Thanks for your feedback. My first thought was multi-timbral as well,
though it doesn't SEEM to be timbre-related.
~Mark

[Steve Worley [e-mail] [KurzList]]

the Juno 106 was a Roland 6 voice analog synthesizer from the late 80s - not sure where any knowledge of it’s sound design could relate to digital sampling technology.



On Jul 19, 2017, at 3:59 PM, Caleb Garner ***@gmail.com [KurzList] <***@yahoogroups.com> wrote:

I don’t know the Kurzweil products intimately but i’ve owned and read about enough other products (Juno 106 and others).. it sounds like a “voice chip” problem though with K2500 having 48 voices I imagine they have something more sophisticated than imagining 48 actual independent voice chips to swap out. However it’s managed by a K2500, I bet it’s still in that realm of where the voices are managed / sound distributed.


I wonder too about multi timbral stuff too.. does the “every third” effect EVERY note regardless of which instrument is playing or only resides on one.. i’m guessing it doesn’t matter, but it might help isolate the issue?

Sincerely,
Caleb Garner / 615-818-8483

Post by ***@yahoo.com [KurzList]
Friends,
My K2500RS has begun outputting distorted audio. It is not constant, but repeating (ie: if you strike a key on a controller repeatedly, every third strike out of four distorts.) I did a hard reset, ran the full series of tests (all passed) tried an imported demo sequence, cable swaps, changed all outputs--no change in the symptom. I thought I'd see if anyone else had experienced this before I pull it from the rack and pop the hood. The only other thing I've found is that I can no longer access the internal hard drive (I have a spare I can swap.) All the installed ROM (orchestral/contemporary/piano) works fine (albeit with the distortion.)
Any ideas?
~Mark

[Caleb Garner [e-mail] [KurzList]]

Right just saying similar “every “ x notes is the same behavior you would run into with faulty chips. The point isn’t analog vs digital. it’s simply saying that something in the voice chain is defective. When the individual DCO chips are defective and it’s that “voices” turn to play a sound you end up with something weird because that particular voice is damaged.

Though it seems like if we do have 48 voices this would only happen every 48 notes or something like that.. since 48 notes can be simultaneous.. which brings up a question.. if you do a six note chord.. can you tell if you get 2 defective sounds or still just 1?

Does it matter which note is pressed? makes me wonder if every 3rd note is not the third note pressed.. like.. every D# acts up? or is it that if you hit A B (C) B B (G) C A (A)
 or A B (C) A A A B (C)


One idea though.. in the troubleshooting.. if you were to make an instrument that is a mono instrument.. like a minimoog type of patch.. will it still act up.. or maybe it’s when polyphony overlaps that causes something strange to happen.

Just putting out ideas to help isolate where the problem could be.

Sincerely,
Caleb Garner / 615-818-8483

Post by Steve Worley ***@cox.net [KurzList]
the Juno 106 was a Roland 6 voice analog synthesizer from the late 80s - not sure where any knowledge of it’s sound design could relate to digital sampling technology.
I don’t know the Kurzweil products intimately but i’ve owned and read about enough other products (Juno 106 and others).. it sounds like a “voice chip” problem though with K2500 having 48 voices I imagine they have something more sophisticated than imagining 48 actual independent voice chips to swap out. However it’s managed by a K2500, I bet it’s still in that realm of where the voices are managed / sound distributed.
I wonder too about multi timbral stuff too.. does the “every third” effect EVERY note regardless of which instrument is playing or only resides on one.. i’m guessing it doesn’t matter, but it might help isolate the issue?
Sincerely,
Caleb Garner / 615-818-8483

Post by ***@yahoo.com [KurzList]
Friends,
My K2500RS has begun outputting distorted audio. It is not constant, but repeating (ie: if you strike a key on a controller repeatedly, every third strike out of four distorts.) I did a hard reset, ran the full series of tests (all passed) tried an imported demo sequence, cable swaps, changed all outputs--no change in the symptom. I thought I'd see if anyone else had experienced this before I pull it from the rack and pop the hood. The only other thing I've found is that I can no longer access the internal hard drive (I have a spare I can swap.) All the installed ROM (orchestral/contemporary/piano) works fine (albeit with the distortion.)
Any ideas?
~Mark

[[e-mail] [KurzList]]

I'm sorry to hear you're experiencing problems with your K2500RS. I had a very similar situation with my K2500RS.

In the MASTER menus there is a utility menu. Select select UTILITY, then select VOICES. When a note is played, an X will appear on the display to represent each voice. Check to see if the bad voice occurs with the same X.

This is the advice given to me by Roger J, a prolific Kurzweil technician who posts here and is a wealth of Kurzweil technical knowledge. In my case, I had a faulty engine board which caused distortion on a single voice in the upper limits of polyphony, and I decided to replace the board. I purchased my engine board for $70 from Alex Goetsman, who also occasionally posts here and I recommend him just because he's a nice guy and has always come through for me, over-delivering and under-promising.

If you do decide to replace your engine board, see if you can find a "revision K" board, which is the latest revision. The replacement of the engine board is pretty straightforward - take pictures of everything, remove the audio connector board, digital connector board, daughter board, standoffs, engine board. The engine board uses longer screws than the daughter board, so make note of that.

But, there could be other issues. Check for obvious stuff like bulging or leaking capacitors. Those are easy to replace since everything on these Kurzeweils use through-hole manufacturing, and the common parts like that are pretty easy to obtain.

Best of luck to you!

[Gordonjcp [e-mail] [KurzList]]

Post by ***@theluthers.net [KurzList]
This is the advice given to me by Roger J, a prolific Kurzweil technician who posts here and is a wealth of Kurzweil technical knowledge. In my case, I had a faulty engine board which caused distortion on a single voice in the upper limits of polyphony, and I decided to replace the board. I purchased my engine board for $70 from Alex Goetsman, who also occasionally posts here and I recommend him just because he's a nice guy and has always come through for me, over-delivering and under-promising.

That's who I got my RAM and sampling board from. I guess he's like the
Kurzweil equivalent of that guy with about 20 old Volkswagen Beetles
around his house and yet another arriving every week or so on a trailer,
who's always got juuuust th thing you need, right here in the shed ;-)

[[e-mail] [KurzList]]

Thanks for all the advice! I'm still troubleshooting. So far, I've eliminated most of what has been suggested in this thread. Going to see if I have signal at the digital out (which I rarely use.) After that, I'll pull it from the rack and open it up. I'm quite comfortable working on it (I've done quite a lot to it in the past.) Good to know you all have had the same positive experience with Roger, etcetera, as I have. This group is a life saver!

I'm curious about the capacitor suggestion as well. That was one of my first thoughts when I noticed the distortion.

Updates will follow. Thanks again, everyone!

~Mark

[[e-mail] [KurzList]]

I guess he's like the Kurzweil equivalent of that guy with about 20 old Volkswagen Beetles

around his house and yet another arriving every week or so on a trailer,
who's always got juuuust th thing you need, right here in the shed ;-)

Ha! Truth be told, I've got more than a few spare boards around my house too. I had an opportunity to purchase a K2500X wheel assembly for $50, but this one guy was selling the entire guts of his K2500XS less the case and keybed for $75, so I went with that option. Turned out the only "bad" thing he had was the engine board that had an obviously fried diode, but I have a "Kurzweil K2500 Goody Box"...

[Terina Gleason [e-mail] [KurzList]]

--------------------------------------------
On Thu, 7/20/17, Gordonjcp ***@gjcp.net [KurzList] <***@yahoogroups.com> wrote:

Subject: Re: [KL] Re: K2500RS Analog output distortion issue
To: "***@theluthers.net [KurzList]" <***@yahoogroups.com>
Date: Thursday, July 20, 2017, 5:01 PM


 









On Thu, Jul 20, 2017 at 12:55:29PM +0000,

Post by ***@theluthers.net [KurzList]
This is the advice given to me by Roger J, a prolific

Kurzweil technician who posts here and is a wealth of
Kurzweil technical knowledge. In my case, I had a faulty
engine board which caused distortion on a single voice in
the upper limits of polyphony, and I decided to replace the
board. I purchased my engine board for $70 from Alex
Goetsman, who also occasionally posts here and I recommend
him just because he's a nice guy and has always come
through for me, over-delivering and under-promising.



That's who I got my RAM and sampling board from. I
guess he's like the

Kurzweil equivalent of that guy with about 20 old Volkswagen
Beetles

around his house and yet another arriving every week or so
on a trailer,

who's always got juuuust th thing you need, right here
in the shed ;-)



--

Gordonjcp MM0YEQ













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Nici o parte a actualului teritoriu sa nu fie detasata de Romania

[[e-mail] [KurzList]]

UPDATE: Issue resolved.

After looking for other possible causes of the output distortion, I swapped the engine board for an earlier revision I had from a "donor" K2500R. Problem solved! Back to outputting sweet Kurzweil sounds.


Many thanks to all who offered suggestions over the last month. Rock on!


~Mark

[[e-mail] [KurzList]]

Awesome news Mark!

You might want to check the PLD revisions of your "bad" board against the revisions on your "good" board and swap them if necessary.

[[e-mail] [KurzList]]

Thanks Dan! While I had everything open, I checked all the rev levels. It's a testimony to how well designed these things were that I was able to pull the dormant engine board from the donor after it sat for over two years, swap it in, power back up, and VOILA! Back in business.

It's a good thing we Kurzweil people hoard spares!


~Mark