[KL] Taking a K2000 on the road - feedback?

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I have been keeping my old K2000 (with sampling and expansions) in the studio. I bought it second hand a few years ago and did a few fixes on it such as changing the display and maxing the memory. It had been already modified with the floppy replaced by a zip drive.
On a couple of occasions it has needed to be restarted when powered up as it would display a blank screen. Turning it off then on again always fixed the problem.
Now I am thinking of making it part of my live rig - it has the best keyboard feel of all the non-weighted keyboards I have, it offers a wide range of sounds, multitimbrality and a built-in sequencer as well as multiple outputs (to send a click to the drummer). It would be the perfect complement to my Nord Stage.
But I am worried about its reliability on the road given that it's quite an old keyboard, and the couple of incidents when it needed restarting suggests not all is 100% well with it.
So I am wondering - do any of you still gig with a K2000 and what are you experiences with regard to reliability?


Thank you


Bruno

[[e-mail] [KurzList]]

I am worried about its reliability on the road given that it's quite an old keyboard, and the couple of incidents when it needed restarting suggests not all is 100% well with it.So I am wondering - do any of you still gig with a K2000 and what are you experiences with regard to reliability?

Hi Bruno,

Have a tech recap the power supply section, especially that 33000uf (C202) primary 5V filter and the 4700uf (C192) and 1000uf (C190) smoothing caps. Actually, check all the electrolytic capacitors for visual defects like swelling/discoloration at the top, leaking at the base or even ones that appear bent over (they usually stand.) Testing capacitors requires removal, and let's face it -- if you have to remove a component to test it and maybe replace it with a part that's $0.25, I usually just replace them and keep any tested good caps around for "emergency" purposes. It's also a good practice to check the diodes and diode packs, which are much easier to check since they only need to have one leg lifted. These are probably the weakest areas of the K2X series.

On a couple of occasions it has needed to be restarted when powered up as it would display a blank screen. Turning it off then on again always fixed the problem.

That sounds a lot like the reset circuit that drops when the +5Vdig supply is out of spec. What you're describing could be a marginal capacitor not charging fast enough initially to pass stable voltage and the reset circuit does its job; when the unit is turned on for enough time, current builds up slowly, but the residual charge isn't immediately dissipated and subsequent power off/on leaves enough voltage and allows the reset circuit to resume normal operation. It could also be a diode like D10/D11, the half-wave rectifier diode pack D19, or even the IRFZ30 5V regulator.

That 33000uf cap is notorious for failure since it's only rated for 3,000-5,000 hours, and all kinds of strange issues can be traced back to the power supply across the entire K2X series. In fact, you can look at a popular page outlining the replacement of the display in the K2000 keyboard (helium.deepgreen.ca/dave/K2000_Display) and see in his pictures the 33000uf capacitor obviously swollen, ripe for failure. I'm a tech and tend to go overboard when seeing power supply issues in my Kurzweils, replacing the capacitors with 105deg/F low ESR rated capacitors from Nichion or Rubycon, voltage regulators and any diodes that are even remotely suspicious.

Let me bring this all back to reality and say that this is in no way a professional diagnosis of your issue -- I'm only relaying my own experience with refurbishing and repairing my own Kurzweils - I have 6 of them.

[Jon Hartmann [e-mail] [KurzList]]

it depends on the mileage of the instrument.. yes, I have a K2vx, but it;s like new..and I depend on it

On Wednesday, November 29, 2017 7:38 PM, "***@theluthers.net [KurzList]" <***@yahoogroups.com> wrote:


  >> I am worried about its reliability on the road given that it's quite an old keyboard, and the couple of incidents when it needed restarting suggests not all is 100% well with it.So I am wondering - do any of you still gig with a K2000 and what are you experiences with regard to reliability?

Hi Bruno,

Have a tech recap the power supply section, especially that 33000uf (C202) primary 5V filter and the 4700uf (C192) and 1000uf (C190) smoothing caps. Actually, check all the electrolytic capacitors for visual defects like swelling/discoloration at the top, leaking at the base or even ones that appear bent over (they usually stand.) Testing capacitors requires removal, and let's face it -- if you have to remove a component to test it and maybe replace it with a part that's $0.25, I usually just replace them and keep any tested good caps around for "emergency" purposes. It's also a good practice to check the diodes and diode packs, which are much easier to check since they only need to have one leg lifted. These are probably the weakest areas of the K2X series.

Post by ***@fastmail.fm [KurzList]
On a couple of occasions it has needed to be restarted when powered up as it would display a blank screen. Turning it off then on again always fixed the problem.

That sounds a lot like the reset circuit that drops when the +5Vdig supply is out of spec. What you're describing could be a marginal capacitor not charging fast enough initially to pass stable voltage and the reset circuit does its job; when the unit is turned on for enough time, current builds up slowly, but the residual charge isn't immediately dissipated and subsequent power off/on leaves enough voltage and allows the reset circuit to resume normal operation. It could also be a diode like D10/D11, the half-wave rectifier diode pack D19, or even the IRFZ30 5V regulator.

That 33000uf cap is notorious for failure since it's only rated for 3,000-5,000 hours, and all kinds of strange issues can be traced back to the power supply across the entire K2X series. In fact, you can look at a popular page outlining the replacement of the display in the K2000 keyboard (helium.deepgreen.ca/dave/K2000_Display) and see in his pictures the 33000uf capacitor obviously swollen, ripe for failure. I'm a tech and tend to go overboard when seeing power supply issues in my Kurzweils, replacing the capacitors with 105deg/F low ESR rated capacitors from Nichion or Rubycon, voltage regulators and any diodes that are even remotely suspicious.

Let me bring this all back to reality and say that this is in no way a professional diagnosis of your issue -- I'm only relaying my own experience with refurbishing and repairing my own Kurzweils - I have 6 of them.



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This is brilliant, thank you so much! Are these cap replacements within the reach of a beginning to intermediate level solderer? Finding a tech without a 3 months waiting list is difficult in my area especially this time of year.

Bruno

[[e-mail] [KurzList]]

(trying to reply again after Yahoo's snafu...)

First, try getting the K2000 service manual from the files section of the "Kurzweil-K2600" group and performing all the power supply tests and calibrations, measuring the voltages at all the test points outlined starting in section 5.1.2.4. The K2500 service manual has a more straightforward test regiment outlined beginning in Section 5, and the section labeled "K2500R Power Supply Test". The audio/power boards on the K2000R/K2500R are nearly identical -- in fact the audio/power board on the K2500R series is labeled "K2000/K25000", and the test points (even if not identically labeled) should be rated for the same voltages. In case you're wondering, I keep bringing up the rack version since it has the combination audio/power board style found in the K2000 keyboard, while the K2500 keyboards have a separated PSU and audio board.

You'll need a desoldering pump and some desoldering wick. I have the spring-suction handheld type (which is surprisingly efficient), and an electric foot-operated station; both have their advantages and disadvantages, like the spring-loaded manual desoldering pump is good at excavating a lot of solder at a time, but I tend to use the electric pump since you can move it around the pin to remove solder.

If you're a beginning level solderer, desoldering can be a bit tricky since you have to desolder and immediately use a thin pair of needle-nosed pliers to wiggle the pin in the hole to make sure it doesn't solidify from the any remainder, usually on the other side of the hole on double-sided boards -- this is where the electric desoldering pump comes in very handy as you can desolder and immediately lift and grab the pin with the other hand. Desoldering wick is good to have on hand to mop up and remove any remaining solder stuck in the holes, but this can become quite maddening with a combination of solder wicking, re-applying a small amount of solder to the pad and then removing that with the pump and/or wick. I found a dremel tool on low speed with a 1/32" drill bit (and special collet) does this "clean the hole" trick nicely, as long as you remember to use a dry toothbrush, a shaving brush, plenty of compressed air and finally electronic cleaner on both sides of the board to clean off any solder shavings.

You might want to practice on some old junk electronics before you perform open-heart surgery on one of your most prized possessions...

To answer your question, yes, replacing the caps is definitely with reach of the intermediate solderer. But also check the diodes by unsoldering one leg of the diode and using a meter in diode-test mode to check each one. Lots of videos on YouTube about checking diodes in this manner. Also, acquire the K200/K2500 service manuals. Some good service notes at the end of the K2500 service manual that apply to the K2000 series (possibly even your specific issue) including the notes for "PWROKECO" and "KF351ECO" at the very end.

Three important things --

1) Take lots and lots of pictures of everything from multiple angles, of every step.
2) Keep screws, standoffs, washers and brackets separated, and label them if you must.
3) Replace components one at a time.

[[e-mail] [KurzList]]

Thank you again very much!

Bruno

[[e-mail] [KurzList]]

Another question - I opened the K2000 and sure enough the big capacitor looks all swollen up and ready to explode like a giant pimple. It was referred to as a 33000uF capacitor but the one on my board is 22000uF (16V). Must be a different version of the board. On some archived posts I saw it discussed at 47000uF.

Is it better to replace it with another 22000uF cap or to up its value to 33000uF?


Thank you!


Bruno

[[e-mail] [KurzList]]

That's always disheartening to see. I don't think it can be a a 22,000uF cap.

The other is 4,700, not 47,000 (seriously, look at it)

Here's an image of the schematic from the service manual I screen grabbed with the primary filter and smoothing capacitors circled, with values:

Loading Image... http://theluthers.net/images/k2000-schem-pwr.jpg

http://theluthers.net/images/k2000-schem-pwr.jpg

http://theluthers.net/images/k2000-schem-pwr.jpg http://theluthers.net/images/k2000-schem-pwr.jpg


View on theluthers.net http://theluthers.net/images/k2000-schem-pwr.jpg
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... and here's where they are on a K2000 keyboard (with attribution to Dave at "helium.deepgreen.ca" for the image):


Loading Image... http://theluthers.net/images/k2000-board-cap.jpg

http://theluthers.net/images/k2000-board-cap.jpg

http://theluthers.net/images/k2000-board-cap.jpg http://theluthers.net/images/k2000-board-cap.jpg


View on theluthers.net http://theluthers.net/images/k2000-board-cap.jpg
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If you look closely at this picture, you can see the big 16v/33,000uF capacitor bulging. However, I'd say if that big capacitor is labeled 22,000uF in your K2000, it may have been replaced with a lower value which is no bueno. The only capacitor I can see on the schematic that even looks like it might be what you describe is C203, which is a 2,200uF/6v cap coming off the Q12/Q13 to supply +5Vdig to the CPU's SRAM and PRAM.

Give your boards a good inspection and look for any more electrolytic capacitors that might be swelling or leaking. They're all old caps (25 years old now), and these three are the ones that get worked the most. You can replace the 16V with 25V equivalents (and not an entirely bad idea), and you might want to consider using Rubycon/Nichicon 105deg/F rated capacitors instead of the 85deg/F versions.

Nearest each of these components, the component number is printed on the board. Is there any chance you could get that info - just to verify?

[[e-mail] [KurzList]]

Thank you again

I checked again and it's definitely the one. It's C202 and it is 22000uF. I actually have a second K2000 (not working) that I'm keeping in storage for parts and I checked it too and it also has a 22000uF at this position.


https://photos.app.goo.gl/UOdPhQhNTq8qNl9U2 https://photos.app.goo.gl/UOdPhQhNTq8qNl9U2



https://photos.app.goo.gl/LIqLj2UStbUkWDqo2 https://photos.app.goo.gl/LIqLj2UStbUkWDqo2



I wonder if there's a different board version out there.


But would there be any harm in replacing it with a 33000uF cap? I actually ordered both caps just in case, but they are taking a while to get here :-(.


By the way as I was doing this I also noticed a loose wire where the sampling option has been added to my board (by direct soldering). Should that wire be connected somewhere and if so, where? I can't find the sampling board installation instructions anywhere


https://photos.app.goo.gl/MxhiaAxFmofxve992 https://photos.app.goo.gl/MxhiaAxFmofxve992



Bruno

[[e-mail] [KurzList]]

Bruno,

Wow -- that thing looks like it's about to pop!

Honestly I don't know what to tell you -- all the documentation I have states that cap should be 33,000uF. Every Kurzweil unit I have uses a 33,000uF cap in the power supply. The service manual states this should be a 33,000uF cap for both the keyboard and rack units. But hey, here's another pic of someone's K2000 opened up and sure enough, a 22,000uF capacitor:

Loading Image... http://tk386.com/k2000_innards/DSC_8153.jpg

http://tk386.com/k2000_innards/DSC_8153.jpg

http://tk386.com/k2000_innards/DSC_8153... http://tk386.com/k2000_innards/DSC_8153.jpg


View on tk386.com http://tk386.com/k2000_innards/DSC_8153.jpg
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(note the swelling...)

Maybe Roger J can weigh in on this -- I really didn't get into the early Kurzweils except for my K2000R...

As for the loose wire from the sampling option, it came off the other end of R9.

[[e-mail] [KurzList]]

Many many thanks!

[[e-mail] [KurzList]]

To conclude this thread, I have replaced the 22000uF cap with a 33000uF one (used this one: http://au.element14.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=43&urlRequestType=Base&partNumber=1040945&storeId=10184 http://au.element14.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=43&urlRequestType=Base&partNumber=1040945&storeId=10184) Plus the other two caps next to it.


And so far it's all working very well!


Thank you for all the help!


Bruno

[[e-mail] [KurzList]]

Awesome Bruno -- good for another 20 years!

Did you get the sampler cable fixed as well?

[[e-mail] [KurzList]]

Awesome Bruno -- good for another 20 years!

Did you get the sampler cable fixed as well?





Yes, soldered it back in place. I haven't actually tried sampling anything or playing with the digital outputs yet so don't know if that was a success or not, but the machine hasn't complained so far

Bruno

[[e-mail] [KurzList]]

Post by ***@fastmail.fm [KurzList]
But would there be any harm in replacing it with a 33000uF cap? I actually ordered both caps just in case, but they are taking a while to get here :-(.

In the filtering stage of a power supply, most likely not. These caps might be the +100%/-20% variety, which is why they've all been replaced with 33,000uF +-20% varieties. Since these are so prone to failure, the engineers probably replaced them with a higher capacitance to decrease the ripple voltage and (hopefully) with the lowest ESR rating available.

If this were my keyboard, I'd want the 33KuF variety in this location. I'd also replace C192 and C190 with the equivalent values since those have managed to stay static across the entire K2X line.

Best of luck!