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Fixing a Casio SK-200 Music Keyboard

bnitz — Sun, 28 Feb 2010 23:40:32 +0000

Sometime in the late 1980s or early 90s I bought a Casio SK-200 sampling music keyboard. It has been a lot of fun over the years. I’ve sampled everything from radio static to hulusi’s and harps. The sound quality isn’t brilliant, it’s only 8-bit sampling at 10 kHz, but slightly higher quality than the more popular but older Casio SK-1. I was surprised to learn that 20 years after I bought this keyboard, there doesn’t seem to be a similar “kid-sized” fun sampling keyboard. So I hung onto it and now my kids have fun with it. I think it may have helped encourage my little boy to talk.

The little guy helped break it, but we can fix it and learn how it works.

Boys will be boys, and the little guy loves playing music keyboards with his feet. So one of the black keys was wobbling like a loose tooth.

Who needs C# anyway?

I decided to take it apart and try to epoxy glue the key. Wow there were quite a few screws inside! I read that the SK1 had 4 screws holding the key assembly into the case, this one had 14! Ideally I would replace the cracked key or swap it for a seldom used one at the top of the range, but while white keys are discreet, black keys are grouped, about 10 together on a single piece of plastic. The plastic has exactly the right springiness to make the keys bounce well. The SK-200 is full of discrete electronics, many ICs capacitors, diodes, transistors… all work together to make a robust and wonderful keyboard. Here is a photo of the M4135-MAIM board:

Main logic and sound circuit board SK-200

Here are some of the parts on the M4135-MAIM board

TC4066BP (3)	TC40175BP(2)
5218/4558?(2)	TC74HC174P
TC74HCU04	8517PX204
TC74HC157P2	MSM6294-03
74HCABP(2?)	7416PX204(uPD4464C -15L)
tM6283-02	HD61702A04

The other circuit board has a few small ICs and lots of transistors, capacitors, resistors and diodes. It appears to be the power supply and audio amplifier board.

I took apart a cheap modern keyboard recently and only found one of those ugly black blobs. You can see why keyboards such as this and Casio’s SK-1 are sought after by circuit benders. There are thousands of points where circuit modifications could be made. I found a point where it would be easy to pitch bend and the trick of piggybacking an extra memory bank and soldering the data-select to a toggle switch wouldn’t be too difficult, but I think I’ll leave well enough alone. With this minor repair the keyboard is just as fun as it was in the 1990s and neither Casio nor Yamaha appear to have taken advantage of 20-years of advancements in memory and sampling electronics and given us a higher quality portable sampling keyboard. So this was well worth fixing.

One word of caution, if you do use epoxy, only use enough to fill the crack. You don’t want the stiffness of epoxy to mess up the key bounce. And be very careful you don’t glue the key to the case.

SourceJuicer at Beijing OpenSolaris User’s Group

admin — Mon, 08 Feb 2010 08:11:08 +0000

While I was in China working with the desktop QA team,

I was invited to present SourceJuicer to the Beijing OpenSolaris Users Group/Beijing GNOME group combined meeting. (Thanks Emily and all!)

An engine crosses Malahide rail viaduct testing in progress!

bnitz — Sat, 14 Nov 2009 13:18:42 +0000

I was pleasantly surprised at the quick progress in plugging the breach in the weir and repairing the broken viaduct. Today marked a milestone, it was the first time since the rail problem that I saw a rail car traverse the broken section of track!

14 November 2009, railcar goes across malahide estuary.

Use it or lose it patent legislation proposed in Minnesota

admin — Sun, 13 Sep 2009 20:10:08 +0000

My friend Ron at inventorsagarage.com found this proposed Minnesota legislation which would grant an employee the right to use a patent if his/her employer sits on the patent for too long:

(b) An employer who has a right to develop or utilize an invention or proposal 1.11must make a substantial investment in the invention or proposal within five years of the 1.12submission of the invention or proposal or forfeit all rights and interests in the invention 1.13or proposal to the employee.

I’d wondered about this possibility years ago when I noticed how common it was for an invention to languish in an employer’s defensive patent armory while everyone, including the inventor, is blocked from doing anything with it. There are many reasons for this, for example a company may be operating in a business where the patent might not be applicable. Do we want the idea for a 90% efficiency solar panel or a cure for cancer to sit in a warehouse because the inventor’s day job is at an investment firm or oil company which has absolutely no financial interest in developing the technology? Even when a new patent aligns with a company’s core business, developing the patent might not figure into to the company’s immediate business plan. SEC guidelines force companies to focus on near term (90 day) profits. IMHO this discouraged R&D and may have contributed to the fact that NASDAQ remains below the trend line set in the pre PC, pre-Internet vacuum tube era. The proposed ‘use it or lose it’ law might help uncork some of the innovations which, I imagine are sitting in a warehouse not unlike the one at the end of ‘Raiders of the Lost Ark.’

I agree with Ron that this law has very little chance of passing, but at least it has seen the light of day. If a similar law has passed in another state or country it would be interesting to see if it encouraged innovation. I suspect it would discourage large companies who have every reason to want to maintain their patent hoard, but it would also encourage small start-ups who would take advantage of the wasted IP. Sooner or later we will reach a critical mass of inventors whose creations are kept under wraps and there will be a level of reform somewhere. Then perhaps one day the patent system will live up to the mission of creating an environment that “encourages investment in innovation, and fosters entrepreneurial spirit.”

A carpenter’s explanation of OpenSource

admin — Thu, 10 Sep 2009 20:22:33 +0000

Imagine that you are a shop teacher intending to teach children how to build a wooden footstool:

The shop teacher and the prefab ‘lumber’yard
You go to the lumberyard and ask for some lumber and nails. The guy at the lumber store shakes his head and says, “Sorry, we don’t got that, we only carry EasyDone or NanoHouse products. How about this beautiful prefab bathroom?” You tell him you don’t need a bathroom.

“Perhaps I can interest you in a EasyDone kitchen?” he says.
“Just wood and nails,” you say. Frustration is beginning to show in your voice.
“O.K. then you must choose between an EasyDone or NanoHouse prefab livingroom.”
“I only need wood and nails! Ten penny nails, 2X4s, plywood!”
“We don’t sell that.”
“O.K. then how much is an EasyDone bedroom, I can take it apart and use the wood and nails.”
“$40,000″
“What? That is far too expensive for my budget!”
“It’s fully integrated, painted, the carpet is in place and the bed is even included, it’s ready to go!”
“But it doesn’t do what I need. I’m only going to take it apart and we are going to use the wood in shop class.”
“Wait a minute. Did you say something about taking it apart?”
“Yes! It doesn’t do what we need so I have to take it apart so my kids can rebuild!”
“No, I can’t sell it to you for that, it’s against the law, violates the EULA. Besides, all the joints are epoxy rivet-welded together. You couldn’t possibly take it apart without turning it into sawdust.”
“But I need the raw materials for my students to build a footstools!”
“Go away. I need someone to buy my prefab bathrooms, I have some overstock.”
“Fine!” You say, “I’ll take my business elsewhere.
“There is a NanoHouse prefab garage store down the street.” he offers.
“I’m not interested! And if I ever do need a new bathroom, I’m going to build my own!”
“Oh no you don’t. NanHouse has a patent on those.”

Opensource software is a raw material which can turned on a lathe, nailed together. It can (and must!) be replicated at any stage of customization or enhancement. Therefore, it improves as it is used. If you can’t buy exactly what you want, you can build it or put together the components and configure them to meet your needs. Free software doesn’t eliminate the need for software expertise anymore than raw lumber eliminates the need for carpenters. Free and opensource software (FOSS) is a good fit for education where thousands of schools across the country have similar, but perhaps not identical needs. Ironically, many proprietary software companies have all but abandoned the educational market because of widespread piracy of proprietary software in schools.

When schools had solid federally subsidized budgets for computers, proprietary software running on proprietary operating systems installed on proprietary fat client computers (with a shelf life of little more than one semester), may have seemed a good idea. But this was never an efficient use of funds. For some schools it was the equivalent of buying a pre-fab house for the shop class to take apart and build into footstools and candle holders. Times have changed, educational money has disappeared. Such inefficiencies are now impossible to overlook. In order to give children the best chance of a bright future where they can compete in the global economy, we need find these holes where our government is throwing tax money, and fill them as quickly as possible. It is becoming obvious that to balance their budgets, governments and educational institutions must utilize opensource software and eco-efficient, future-proof, low TCO hardware wherever possible.

ZFS in Apple’s OSX 10.6 Snow Leopard

admin — Thu, 03 Sep 2009 16:46:46 +0000

Storagemojo’s blog has some interesting comments about Apple’s decision to leave the next generation ZFS volume-manager/filesystem out of OSX 10.6 Snow Leopard. I have no idea why they did this. Command line read-only ZFS existed in OSX 10.5 Leopard and an opensource plug-in gave it read write capability. ZFS has proven itself both in saving Apache.org time and headaches after a recent security breech. This is from Apache.org’s incident report:

aurora.apache.org runs Solaris 10, and we were able to restore the box to a known-good configuration by cloning and promoting a ZFS snapshot from a day before the CGI scripts were synced over. Doing so enabled us to bring the EU server back online, and to rapidly restore our main websites. Thereafter, we continued to analyze the cause of the breach, the method of access, and which, if any, other machines had been compromised.
…
What worked?
* The use of ZFS snapshots enabled us to restore the EU production web server to a known-good state.

The consensus seems to be that Sun’s CDDL license wasn’t a factor in Apple’s removing this feature. Sun’s dtrace is already in OSX under CDDL. GPL won’t help here because the OSX kernel is under a BSD license and much of the software and hardware drivers which are able to link to BSD licensed kernel would not be able to live with GPL code. I doubt it is a stability issue, as I’ve mentioned, read-only ZFS has been in OSX for quite some time and many Linux and Windows servers have gone into production based on less reliable and far less scalable filesystems.

Some have claimed that ZFS is only appropriate for large servers. Nothing could be further from the truth. I regularly use it on a tiny Solaris laptop with 2G of RAM. The snapshot, rollback and related boot environment management features are enormous timesavers. Time machine is a typically beautiful Apple GUI built on top of a slow (rsync?) kludge. Merge this GUI with ZFS, and it’s a marriage made in heaven. Snapshots take almost no time or redundant space (Copy on Write), rollbacks are nearly instantaneous. Why wouldn’t artists, writers, musicians and other creative people in Apple’s prime market want instantaneous automatic versioned snapshots of their work?

I don’t know why Apple made this decision. Maybe they want to make their money on a ZFS based storage appliance. In any case, I’m glad BSD and Solaris 10 and OpenSolaris already have ZFS. Even if my Mac or Windows desktop has to rely on archaic HFS+ or NTFS filesystems for another year or two, at least we can push storage out to a more reliable and scalable filesystem running on a modern server-class OS.

28 August Broadmeadows low evening tide

admin — Fri, 28 Aug 2009 21:33:05 +0000

I don’t remember the broadmeadows estuary water level ever being quite so low so close to a high tide. Notice the entire length of the pier is out of the water. Today is partway between a spring tide and neap tide so I wouldn’t expect extremes. The wind was strong out of the west but this is also typical. It struck me that if the channel through the eroded section weir is considerably deeper than the others, eventually the estuary will settle to a lower level.

Video taken 17 days before Malahide railway collapse

admin — Mon, 24 Aug 2009 17:29:04 +0000

Here is a movie I took on 4 August, 2009 at approximately 8:30 p.m., only 17 days before the railway collapsed:

See if you can guess which support is the bad one.

Repairing Pentax *IST DL DSLR mode switch

admin — Mon, 17 Aug 2009 23:08:15 +0000

Update February 8, 2010

The problem came back two more times while I was in China but while I was shopping for and considering buying a replacement camera, some guys in the basement of Top City Electronics in the Zhonguancun district of Beijing fixed it for about $20, while I waited. I watched and saw that in order to remove the cover completely it is necessary to remove another screw inside the battery compartment! This allowed him to better access to the mode switch contacts. He used a tweezers to sand the contacts with a very fine sandpaper and put the camera back together, being careful to route the wires properly so they didn’t show up in the top LCD display. If by chance the problem isn’t fixed, now I know how to access the part. I sure wish the U.S. and Ireland had such quick and efficient service centers. We throw so much electronics away because of the high labor cost to fix it!

Update December 11,2009

After a few months the odd switch behavior came back and today it was bad enough to make it difficult to get photos of the kids with Santy. So I referred to my blog to repeat my contact cleaning effort. This time I took off one more screw on the right side (from photographer’s point of view) which gave me more room to take out one of the screws of the micro circuitboard. I think if I knew how to safely detach the on/off switch, I could take the entire top off and really get at it, but it looked pretty difficult and there was potential to damage the microcontacts on the power switch which we don’t want!. So, my assumption is that my 80% isopropyl alcohol was not pure enough (probably true) and didn’t contain any other lubricants to continue to protect the contacts and base. It turns out that the pad is copper instead of carbon which is probably more durable in the long run and less prone to contact noise such as what you’d get from a carbon/copper audio volume control. So, this time I used a ‘tuner cleaner’ contact cleaner spray. I’ll let you know if I have to do this again in a few months, but so far so good!”

Problem:

I encountered a problem with my 3 year old Pentax *IST DL Digital SLR. The symptom is that after selecting a mode (P/Program, Av/perature Priority, Tv/Shutter Priority…), the camera would randomly go into another mode with movement. In my case, Program mode became Auto Picture (green) mode. Av would occasionally become Manual… The problem was made worse by pressure on the top, such as that which a hotshoe flash would cause. Occasionally flash photos would be dramatically overexposed as the camera slipped into another mode at the moment the flash went off.

Solution:

After discussing the problem with my brother (an experienced electronics repair guy) and investigating the cost of repair versus the cost of getting a new or refurbished SLR, I decided to risk taking the bottom cover off. This displayed a test jig ribbon cable but not much useful. So I decided to carefully take the top cover off. I used Enzo’s IST-D disassembly instructions as a guide. The DL construction is slightly different and to get at the mode switch I didn’t need to disassemble nearly as far as Enzo did for his InfraRed modification!

Before I go on, I must warn you that once you take the cover off, any warranties are void (not a problem for me, as I purchased the camera in 2006 at the now defunct Circuit City), and there is always a chance the camera will come out worse than when you started. Don’t say I didn’t warn you, you wield a screwdriver at your own risk! Now, let’s get started. This is what you’ll need:

One good jewelers philips screwdriver
One very small slot screwdriver to help pry the top off.
A capful of 97% or purer isopropal alcohol or better plastic safe inert, corrosion resistant, non-residual electronic contact cleaner.
One small foam cleaner swab, such as those used to clean video heads. I tried the Irish version of Q-tips, but I don’t recommend as shreds of cotton got tangled in the very fragile copper contacts!
One tweezers, to extract any cotton shreds from the very fragile copper contacts!
One camcorder or friend to document the procedure.
A container for each screw. Pentax likes variety in their screws, of 8 screws, I think there were 6 unique ones and 2 alike
A nice bright light or headlamp. Jewellers glasses could be useful for those of us over 40!

O.K. Here goes!

: The yellow highlights point to the screws which must be removed.

The first two are long ones behind the eyepiece cover. I went in order clockwise so it was easier to remember which screws went back into which hole (they are almost all different.) Press the flash up button so you can get at the two screws beneath the flash cover. Then remove the batteries. Be careful, there could still be a charge in the flash capacitor!

: There are two screws on the right side

: Here are the two screws under the flash cover.

: Here is one which must be removed on the left side of the camera.

: Now carefully pry up the left side of the camera

It wasn’t obvious how to remove the whole cover without breaking something. The power switch seemed to be holding the right side on. That’s O.K., I was able to pry the left side up enough to get at the modeswitch circuit board. First I checked the ribbon cable (careful, they are sooo easy to break!)

: I removed one more screw here to lower the mode switch board enough to clean the contacts.

I pried open the left side just enough to remove the screw which holds the tiny mode switch circuit board in place. The contacts were copper printed circuit traces, springy (and VERY FRAGILE) copper ‘brushes’ move across these to make appropriate connections. The flash up button is mounted directly on this little circuit board, which explains why sometimes pressing flash up made the camera go into the correct mode.

I was able to see a tiny bit of corrosion on the printed circuit contacts and wipe it away carefully with the isopropyl alcohol swab. But then part of the swab unraveled and got tangled in the copper brushes. Oh No! I carefully used a tweezers to remove the cotton shreds and carefully lifted the contacts ever so slightly so they were as springy as before. I hope you won’t have to do this.

I used a tweezers to put this tiny screw back in place to get the circuit board back where it belongs. Then I reassembled the whole thing being careful to route the wires and ribbon cables so they didn’t get stuck between components. I reinserted the batteries, and it worked. The mode switch now put the camera in the correct mode. Good luck!

Now I don’t have to get a Pentax K-7 or Olympus EP-1 ‘pen’ to replace it just yet, though the weatherproof seals in the K-7 might’ve prevented the corrosion. I’ll save up and hope the price comes down next year.