Profile

Cover photo
132 followers|118,199 views
AboutPosts

Stream

MiK-Music

Shared publicly  - 
 
Needed to test my new camcorder :)
2
Add a comment...

MiK-Music

commented on a video on YouTube.
Shared publicly  - 
 
Nice video!

From what i see - if you look at the right side of the voice board, there really might be some drink spilled into it. You should unscrew the board and look underneath.

Other interesting things: program 45 shows a garbage value for parameter 11. So the RAM is filled with trash. If you get your buttons working, you should load some useful patches using the tape load function to have some reliable data there. There is no factory reset, so loading a full memory dump (you can find WAVs with them in the web i think) is the only way to get this fixed.
Looks like you have some "endless sustain" or so.

The CV system for the voices seems to work, but there still seems to be a problem with gate/trigger signals. You should be able to verify those with the multimeter also - i'm still unsure about the voice LEDs, they sometimes are extremely dark and they look like normal diodes so they are a bit hard to detect. Don't strip the next cable if you're not 100% sure it is the problem.

Your CPU board looks very clean and the mechanical damage of the contact springs i had was due to corrosion, which doesn't seem to be the problem in your case.

I'll follow your progress and try to give more hints, i'm pretty sure we get this baby pushed to his next decades of fresh live. While not "true analog", it's still a very nice machine. The oscillators are not really free-running as they are synced by the computer, but at least DCO1 is an analog integrator-based VCO and the filters and envelopes are also analog. I hope your envelopes are still okay as those chips (the SSMs) are a bit hard to get.

Good luck!
2
DJ EDDIE FM's profile photo
 
Thanks a million for the tips.  It's so much fun to work on these things!  I'll follow up soon.   
Add a comment...

MiK-Music

Shared publicly  - 
 
Yet another LCD backlight fix / display exchange
 
Kawai K5000W LCD exchange

While fixing several EL backlights, the K5000W also had to get that procedure. The backlight still was perfectly okay, but the K5000 is my master keyboard, right in front of me in the studio, so that whining noise of the inverter was simply driving me crazy.

So I made two identical backlights and drivers for them while I was working on the Wavestation, just to find out the K5000 has a mechanically very different display, the backlight was not just 2mm smaller, there also wasn't enough room under the LCD to get the whole set of foils underneath. Leaving away some of the didn't help also, so there was only one option - replace the whole module

Luckily, I found those Everbouquet MG24065G-SBLWU for just 14.95€ on eBay. A quick look at some datasheet has shown it uses a more modern but T6963C compatible controller and has a bit different pinout. No problem, ordered two if them.

Carefully checking everything before putting it into the K5000 revealed that the contrast voltage of the K5000 was acceptable with -9V (just a rough range, I needed to change the contrast later to make it look nice) and I found a datasheet with the same pinout as the K5000 display. Having 2 different datasheets always makes me a bit nervous, so I checked the traces of the display PCB for plausibility and decided in really have a matching pinout. It even uses the original T6963C.

So I just soldered connectors for control and backlight to it, used some 4mm distance pieces and other screws as this panel is thicker than the original and it is mounted fine now. In the PSU, I disconnected the inverter by soldering off one leg of a thermistor, using the whole for the anode of the backlight, through a 15 ohms resistor. Cathode was soldered to a different spare hole.

So it wasn't that complicated and I really like the result. Unlike the original display, it's inverted, but I think it looks good.

This LCD module might also be usable for the Wavestation and other machines using such 240x64 LCDs. 
2
MiK-Music's profile photoJakub Forejt's profile photo
4 comments
 
Fine. In your crop of the service manual, the topmost board is the PSU, unsolder the left leg of TH (between the capacitors). Make sure you bend it away far enough that it doesn't touch anything. Or completely remove TH and put it somewhere with some adhesive tape or so. The left hole (pointing to the closer board edge) is your +5V.
Add a comment...

MiK-Music

Shared publicly  - 
 
Improved backlight quality as i got some 10" panels to steal the backlight from. I really like this now.
 
Korg Wavestation A/D LED backlight, version 2

This looks great. Not 100% perfect but way better than the 1st try. 12.5mA, which is what I will design the booster for (MC34063, 100 ohms sense resistor).

With this current, this backlight should live forever, and besides the work it was even cheaper than the 30€ replacement EL foil, but the biggest advantage is the silence.

The K5000W will definitely get the same mod, the EL foil is still okay there, but getting rid of the permanent noise directly in front of me is worth every minute of work.
1
Add a comment...

MiK-Music

Shared publicly  - 
 
This week's synth hacking - EL backlight modernization.
 
Hohner HS-2/E / CASIO VZ-10M LCD backlight repair

Not the most uniform backlight, but cutting the iPhone backlight parts to the right size, reducing it to 4 LEDs and connecting it to the +15V using a 220 ohms resistor was a cheap fix for the usual problem of dead EL backlights.

It's a bit tricky as you need to take the LCD panel apart with the high risk of damaging LCD connections, but I was careful enough to make this work.

In the PSU, I cut the +5V line to the EL inverter and the output of the transformer to the connector, adding the 220 ohms resistor to +15V there. So I can use the existing cabling for this LED backlight. 
1
Add a comment...
Have them in circles
132 people
Bullet Time's profile photo
Bob Bailey's profile photo
Marcus Prestes's profile photo
Mitch Sams's profile photo
Bettis Shepherd's profile photo
Luigi Carosi's profile photo
Rens de Jonge's profile photo
Mike Pollington's profile photo
Roger Salzgeber's profile photo

MiK-Music

Shared publicly  - 
 
Synth-DIY: Ensoniq VFX repair

This time a little bit different, not a planned walkthrough, but just having the camera running while i restore this nice machine.
3
2
Pete Hartman's profile photoMichael Kukat's profile photo
Add a comment...

MiK-Music

Shared publicly  - 
 
Thoughts about this page

Since g+ allows pages, i use this page to post some repair or DIY related things from time to time. And there are some posts with >100 comments meanwhile, discussions about repairs having to do with the original post.
Meanwhile, YouTube is also highly integrated with g+, i connected my YT channel with this page for obvious reasons.

Today, +Edward Lyman posted a nice follow-up video for my Poly-61 repair session video. And since some days, i'm waiting for some gear i got from eBay that i need to fix and that might result in another video as the reactions for the Poly-61 video were mostly positive, which motivates me to do a bit more like this.

But i'm still not so happy with the way things work out currently. Having >100 comments on one post might be useful to keep things together, but some day, there might be 500 comments on problems of the Poly-61 (yes, indeed a problematic machine :). Nobody will read through them, so one might have a problem answered in the 200th post that needs to be handled again because it is hidden in the masses. There is not even a chance to link back to specific comments - finding them also isn't that easy.

Finding something isn't so great in g+ in general. A community would be a logical consequence as my goal is the interaction that already happened here and there. I try to find the time to help everybody, but i'm happy if my readers help each other on those pages - or a suitable community. But i'm still not so happy with g+ communities, don't know why but they don't really work for me. I'm pretty sure there already are half a million communities handling electronic repairs. Not that it would be better to have half a million pages about this :)

So how can we do this, how can the overall process be improved?

My idea i have in mind since quite a while - share a post directly with me (this page, not my personal g+ profile) to start some discussion. But share it publicly, please. This gives you the chance to attach photos or videos to better describe the problem and it gives me the chance to repost this question here on this page, with a hopefully good caption and as an opening for the discussion, likely adding my first response with the repost or first comment.

I'm aware about the problem having 2 posts then that might get comments, leading to confusion, as i would prefer having the comment thread on the re-post here for easier browsing through them. There are some ways to handle this, like disabling commenting on the original post after a redirection comment to my repost or so.

By the way - i stopped doing private consulting in the past and i will not do it in the future, i simply want to have a bit of time left for my own life. I want all this to be public to be there as help for others also. Some think it's a great idea to insult me if they ask for help on private channels or by posting their email address in YouTube comments and i tell them i don't do free private electronics consulting. Feel free do to so. Blocked. Done. So if you want me to help you, you have to accept this happens in the public.

I would be happy about some input on this and if there is no damn good reason to not do it this way, i would start disabling commenting on the old posts in favor of the new procedure, which hopefully results in some easier handling.
1
MiK-Music's profile photo
 
No feedback... so i turned off comments on some of the posts, especially those with a large number of comments so far.
Add a comment...

MiK-Music

Shared publicly  - 
 
Korg Poly-61 MIDI kit

I have this around here since years but couldn't decide which one of my 3 Poly-61s will get it - besides this i rarely use my studio so i didn't miss MIDI on the Poly-61 yet.

And it's so rare that it might be more valuable if not installed :)

I'm not sure but maybe the Poly-61M is just a Poly-61 with this kit added in the factory. Should work for OP and NP CPU boards, they added the keyboard assigner MCU (8049, ROM code 384) and some other parts to the kit to first upgrade the OP board to a suitable level.
4
maria margarete melo's profile photoboogie man's profile photoMiK-Music's profile photo
13 comments
 
+boogie man Good luck! This programmer should work for the job. If you don't have an eraser, be very careful, you only have one try per EPROM then.
Add a comment...

MiK-Music

Shared publicly  - 
 
After the success with the small LCD of the Hohner HS-2/E, here comes the next level. Not perfect yet, i need a larger backlight, but it develops the right way :)
 
Korg Wavestation A/D LCD backlight modernization

That 8" 4:3 panel backlight definitely is too short. Before doing this procedure with the K5000W also, I will try to find a more suitable solution, I don't like this uneven lighting, I need to move the whole thing more to the left, which I currently can't do because it would get dark on the right then :)

But in general, this works fine. I use 5 LEDs currently, needing about 13.5V, I think I will use a small boost converter for this, maybe even completely DIY as it can be current-regulating instead if voltage-regulating then.

This was a bit difficult by the way. I needed to disassemble the LCD module as the backlight was glued to the PCB and needed several tries to get back all segments. I just dared this because in worst case I have LED-backlit LCDs suitable as a replacement with some mods, but I wanted to avoid having a green backlight in this machine, so I preferred modifying the original module. 
1
Henner Zeller's profile photo
 
This was an interesting journey so far in backlights.
Add a comment...

MiK-Music

Shared publicly  - 
 
Needed it once again while having some trouble during re-cabling some synths...
 
Poor man's MIDI debugger

You're unsure if you MIDI OUT works? Or if your cable end really is the output and not the input.

Just connect a LED between pins 4 and 5 (the ones directly left and right of the center pin) and do something that should send some messages. Hit some keys, turn the mod wheel, play Giana Sisters, whatever.

If nothing flashes, turn the LED around and try again. If still nothing flashes, either your LED or your MIDI OUT doesn't work.

Sure, there are more sophisticated ways, but this one is the simplest I think :)
2
Add a comment...
People
Have them in circles
132 people
Bullet Time's profile photo
Bob Bailey's profile photo
Marcus Prestes's profile photo
Mitch Sams's profile photo
Bettis Shepherd's profile photo
Luigi Carosi's profile photo
Rens de Jonge's profile photo
Mike Pollington's profile photo
Roger Salzgeber's profile photo
Story
Tagline
Music electronics DIY stuff, repair hints and more
Introduction
The new home of MiK-Music's music electronics DIY site

Here, i try to collect my DIY/repair stories in a somewhat clean way and from time to time add some content that was on my web site before i shut it down.

You will not see high traffic here as only completed stuff is posted here and my music electronics related projects all are a bit on ice currently. So i will post about a repair every now and then.

If you want higher traffic and read about all my DIY activities (and all the other stuff i think i need to tell the world), just find my private g+ stream as +Michael Kukat

Some things you should know before asking questions:

No, i will not contact you via mail, you don't need to publish your address here. Those comments are not deleted - if you want to publish your email address, i will not stop you from doing so. But you won't get a mail from me, just the chance for more spam.

Questions in comments that have nothing to do with the posts they are attached to are silently deleted. You can try to create a post just shared with me for this, if the topic itself is interesting, i might repost it here publicly to care about it. Be aware of this and don't put information there you don't want to publish.

No, i will not guide you through a full repair session using comments or chat. By experience, this easily can take 2 weeks for a job i can do within 1-2 hours when i do it myself.

Be aware that my repair/DIY tips require a good amount of electronics knowledge and often some equipment like oscilloscopes and function generators. If you don't have this, my answer very likely doesn't help you at all. If a question reveals the lack of basic knowledge on your side, i might also delete that comment. I'm simply not able to replace several years of education by a bunch of comments here.

Sorry for those restrictions but i simply don't have the time for private electronics consulting, especially for people without the necessary basic knowledge. Or to say things simple: If you have the basics to be able to make use of my answer, you very likely don't need to ask as you can figure out the answer on your own.

I'm totally aware that all this sounds very arrogant but during the last years i learned that i need exactly this level of arrogance to keep away most of those people not willing to use their own brains to solve a problem. You're totally welcome if you know what you are doing and just need a detail hint.

Thank you for your understanding.