KAWAI K5000 Cool Blue LCD!

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KAWAI K5000 Cool Blue LCD!

Postby HideawayStudio » Wed Mar 19, 2014 6:05 pm

Just thought I'd share todays jubilation!...

The backlight had long since failed on my K5000R in the studio. I'm rather fond of this curious additive "secret weapon" so since I had a good outcome retrofitting my SY/TG77s with modern high contrast white on blue displays I started to wonder if I could do the same with the K5000R.

On dismantling the synth and consulting the service manual the original display turns out to be a 240 by 64 dot display with a Toshiba T6963C compatible driver IC on a 20 pin two row IDC header with a high voltage electroluminescent backlight.

I managed to find a company on eBay in China selling a blue display with remarkably similar dimensions with the usual exception with LED backlit displays that it's considerably deeper than the original.

The part number is: (HSM) LCM24064B (If anyone is interested I'll post a link to the supplier)

Cross comparing the datasheet with the schematic revealed an almost identical pinout.

Well after much fiddling around - I managed to make it work!!

There are a number of gotchas that make this project a little tricky...

These are my notes and do not constitute a full installation so please treat as some guidelines for experienced engineers only.

The EL backlight driver needs to be disabled by removing the power transistor (Q2) that drives it (this will cut down noise). Then the white EL backlight cable removed.

The display first needs to be fitted with a 2x18 pin header with the header justified towards the pin 1 end. This very deliberately leaves pins 19 and 20 on the original ribbon cable not connected - I LEARNT THIS THE HARD WAY THAT THESE PINS MUST NOT BE CONNECTED!!

A 2 Pin header is fitted in pins 21 and 22 on the lcd panel. These are wired to the 5 volt rail for the LED backlight - the floppy disk cable is an easy place to pickup 5 volts. Pin 21 is positive (LED Anode) and 22 Cathode.

There are suitable dropper resistors already on the display so no current limiting is required.

There is also a solder link that needs to be changed to put the controller in the correct mode:

Unsolder link J2 and solder J1 instead.

On removing the original display - the 4 display support standoffs need to be removed as the new display must fit much lower in the front panel chassis.

Warning: The top centre tapped screw hole to hold the aluminium front panel in place must be pressed flat and the screw discarded as otherwise it fouls the edge of the new display pcb!

Since the display has to fit very close to the metal panel the 6MHz crystal on the new display must be removed and relocated parallel to the 22 pin display header as there is a large cutout in the metal chassis at this point to permit it to poke through. I glued the crystal upside down at this point on top of an insulating strip and wired the leads back to the pads where the crystal used to be located.

I then lined the metal chassis plate under the display area with insulating tape and fitted the new display complete with 2 pin cable for the 5 volts to the backlight using four 12mm M3 screws. These screws must be only slightly torqued up or the pcb will bend as the display bottoms out on the metal flanges that hold the LCD bezel together.

On powerup you will find the contrast is wildly wrong and needs to be adjusted in the system menu.

Image
A Quick Test Fitment...

Image
Front Panel Back In Place and Looking Great!...

Its so clear now you can the display on the other side of the studio!!
Last edited by HideawayStudio on Sun Nov 09, 2014 10:49 am, edited 1 time in total.
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Re: KAWAI K5000 Cool Blue LCD!

Postby synthroom » Wed Mar 19, 2014 8:25 pm

That's beautiful! Thanks for posting all the info!
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Re: KAWAI K5000 Cool Blue LCD!

Postby rschnier » Wed Mar 19, 2014 8:39 pm

Wow -- that's so sharp and clear it almost looks as if you'd photoshopped in a graphic in place of the display. Congrats!
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Re: KAWAI K5000 Cool Blue LCD!

Postby garranimal » Wed Mar 19, 2014 9:34 pm

Well done that. I too replaced my display but not looking as great as yours there. I noticed your unit uses separate button pcbs around the display. EDIT: My KB version has one u-shaped pcb that recently stopped working. Turned out to be a pin connector not seated properly.
Last edited by garranimal on Sat Mar 22, 2014 3:22 am, edited 1 time in total.
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Re: KAWAI K5000 Cool Blue LCD!

Postby HideawayStudio » Fri Mar 21, 2014 5:27 pm

Just been doing some research and it's looking 99% likely the same replacement display will work in the Korg Wavestation A/D too.

I have ordered another display and my WS A/D is the next on the list for a new display...
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Re: KAWAI K5000 Cool Blue LCD!

Postby Mesmerised » Sat Jun 28, 2014 1:59 pm

I want to post this as a word of warning:
I have tried the above mentioned display mod on my newly acquired K5000S - and now it's a big doorstop. :cry:

I have to mention first, that I'm a rather experienced builder and have built and repaired lots of synths over the years. I know how to read schematics and I know which side of the iron gets hot.

So, I ordered the Display "1pcs 24064 240x64 Dots Matrix LCD Module with Blue LED Backlight" with the exact specifications you mentioned ( LCM24064B-B) from a chinese ebay seller.
I have checked all the available documentation and K5000S schematics and it all fit together very well indeed.
(btw. where did you find the info about the solder link settings? I did what you described anyway)

On power up nothing happened. Trying to find the fault, I found out that the display had short-circuit (Pin 2 to 3= 0 Ohms) and that obviously took the power supply down.
Unfortunately the secondary fuse wasn't the only thing damaged on the PSU.

To get the synth working again, I replaced the original display and cabling and powered the main board by lab PSU.
To my utter dismay the board didn't boot at all. (5v current: 1A)
So, inexplicably, the faulty display took down the main board with it - which is a real bummer! :evil:

I'm not complaining to you, HideawayStudio, and I know that this is my responsibility. But I wanted to warn people, that a) you can get a faulty unit from china and b) it can take down your whole precious K5000!

I checked and double-checked everything I did and I can't find the slightest mistake from my side. :cry:

Well, it was a real beaute and just had a dim display... AAAARGH!
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Re: KAWAI K5000 Cool Blue LCD!

Postby Adam C. » Sat Jun 28, 2014 5:32 pm

Wow! That is terrible! I'm always paranoid about attempting projects like this, and your story doesn't do much to lessen my fears. I'm very sorry to hear about your predicament. Hopefully it can be salvaged. (Thanks for the warning to the rest of us by the way!)
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Re: KAWAI K5000 Cool Blue LCD!

Postby HideawayStudio » Sat Jun 28, 2014 9:52 pm

Mesmerised wrote:I want to post this as a word of warning:
I have tried the above mentioned display mod on my newly acquired K5000S - and now it's a big doorstop. :cry:

I have to mention first, that I'm a rather experienced builder and have built and repaired lots of synths over the years. I know how to read schematics and I know which side of the iron gets hot.

So, I ordered the Display "1pcs 24064 240x64 Dots Matrix LCD Module with Blue LED Backlight" with the exact specifications you mentioned ( LCM24064B-B) from a chinese ebay seller.
I have checked all the available documentation and K5000S schematics and it all fit together very well indeed.
(btw. where did you find the info about the solder link settings? I did what you described anyway)

On power up nothing happened. Trying to find the fault, I found out that the display had short-circuit (Pin 2 to 3= 0 Ohms) and that obviously took the power supply down.
Unfortunately the secondary fuse wasn't the only thing damaged on the PSU.

To get the synth working again, I replaced the original display and cabling and powered the main board by lab PSU.
To my utter dismay the board didn't boot at all. (5v current: 1A)
So, inexplicably, the faulty display took down the main board with it - which is a real bummer! :evil:

I'm not complaining to you, HideawayStudio, and I know that this is my responsibility. But I wanted to warn people, that a) you can get a faulty unit from china and b) it can take down your whole precious K5000!

I checked and double-checked everything I did and I can't find the slightest mistake from my side. :cry:

Well, it was a real beaute and just had a dim display... AAAARGH!


Ooops!

Sounds like you fell into exactly the same trap as I... if you read my writeup you will notice I detailed removing links and avoiding connecting two pins at all costs... I will lay money on there being absolutely nothing wrong with the display you purchased - it's just that it's configured for a different application.

Basically the problem is that one of the config resistors offers a dead short to ground and unfortunately this pin is not current limited with a resistor on the Kawai - to be honest it's just bad design practice all round.

I've subsequently purchased more of these displays and I'm actually pretty impressed with them - the contrast ratio is superb.

My PSU failed in exactly the same way as yours - it's very under-engineered and it seems Kawai made a poor choice of fuse rating and rather than just taking out the fuse it takes out the chopper transistor in the SMPSU as well.

It's highly unlikely any damaged was incurred by the synth hardware itself but for anyone else contemplating this retrofit please make sure the 5V rail to the display is free of shorts to ground before applying the power!
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Re: KAWAI K5000 Cool Blue LCD!

Postby Mesmerised » Sat Jun 28, 2014 10:15 pm

Hi Dan,

thanks for your answer - I kept close to your instructions: unsoldered J2, set j1, keep pin 19 and 20 not connected...

Which jumper might short to ground? J2? (looks clean though...)
Could you give me a hint for a replacement of the transistor Q1, since I can't seem to find this particular Japan transistor 2SA1641?

What bothers me is, that I have tried powering the synth by a lab PSU and it didn't boot... So I'm afraid that there might be more damage than the PSU. :(
(does it need the analog board to be powered to boot? I wouldn't think so...)

I'm pretty devastated but willing to not give up easy on this one!

best regards, Chris
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Re: KAWAI K5000 Cool Blue LCD!

Postby HideawayStudio » Sat Jun 28, 2014 10:28 pm

Mesmerised wrote:Hi Dan,

thanks for your answer - I kept close to your instructions: unsoldered J2, set j1, keep pin 19 and 20 not connected...

Which jumper might short to ground? J2? (looks clean though...)
Could you give me a hint for a replacement of the transistor Q1, since I can't seem to find this particular Japan transistor 2SA1641?

What bothers me is, that I have tried powering the synth by a lab PSU and it didn't boot... So I'm afraid that there might be more damage than the PSU. :(
(does it need the analog board to be powered to boot? I wouldn't think so...)

I'm pretty devastated but willing to not give up easy on this one!

best regards, Chris

Hi Chris... I am very sorry about this - PM me and maybe I can help...
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Re: KAWAI K5000 Cool Blue LCD!

Postby Mesmerised » Sun Jun 29, 2014 4:26 pm

YES! :D

Dan could indeed help me! My K5000S is NOT a doorstop anymore.
The faulty display blew the 5V part of the internal PSU. I tried powering the synth with the old display back inside from an external 5V source but nothing happened.

The thing to know is, that you have to have the floppy disk drive AND the analog part (+/- 17V) connected or the synth will not boot.
It's still alive and I'll now repair it adding a new 5V switching supply module internally. (It's easier and cheaper than repairing the underpowered original PSU, which now will only serve the analog parts)

I still could not find out why the new display has a short. Might have been faulty, as I could not find an error from my side yet.
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Solved!

Postby Mesmerised » Sun Jun 29, 2014 6:29 pm

Image

Success! :D

What a beauty.
It turned out that it WAS my fault. I failed to completely remove the solder from j2 even though I inspected it with the magnifier and it looked clean. :roll:

My eyes might not get better with the time... Hrrmpf.
I feel slightly stupid, but also happy.

In short: Dan's instructions are correct, the K5000 PSU will be killed by short circuits, the LED display is awesome!

Thanks to Dan and good luck to other K5000 owners.
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Re: KAWAI K5000 Cool Blue LCD!

Postby kazper » Sat Jul 12, 2014 2:47 am

I realy like how crisp that unit looks in comparison to the dull display mine has. Can you post some vendor information?

Thanks,

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Re: KAWAI K5000 Cool Blue LCD!

Postby Mesmerised » Sat Jul 12, 2014 1:15 pm

HideawayStudio wrote:The part number is: (HSM) LCM24064B...


I found it via this information.
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Re: KAWAI K5000 Cool Blue LCD!

Postby walkathon » Sun Jul 13, 2014 4:02 am

Great thread, thanks for sharing. Might have to rescue mine from storage to give it this treatment.
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