Akai S900 Replacement LCD Display and OS Version 4

Akai S900 LCD Disply Replacement Repair
Akai S900 LCD Disply Replacement Repair

This afternoon I was able to successfully replace the LCD Display on my newly acquired Akai S900. There are already a few replacement LCD kits available on Ebay but I found them to be rather expensive ranging from $55 to $65 not including airmail to Japan. So instead I elected to find the sources of the LCD displays which I found from buydisplay.com. On Ebay I believe I payed $20 including shipment to Japan for the LCD display that most were providing in their kits.

Akai S900 Cool Blue Display
Akai S900 Cool Blue Display

Installation was not too difficult. After removing the front plate of the Akai S900 I was able to easily remove the old LCD Display. I then clipped the right side two wires going to the Inverter and removed that as well which you can see in the photo below. With the replacement of the new LCD display, the Inverter was no longer needed. On the left side you then have to remove the 14 pin angle connector from the old display so that you can then re-solder it to the new one. This was the only difficult part but with patience and careful desoldering, I was able to remove the pin connector just fine. I then cut the two P-401 wires connected to the inverter so that I could solder them to pins 15 and 16 to power the backlight LCD of the display. The 5V wire is the one soldered near the resistor on the Inverter board for those who know what I’m talking about.

Akai S900 Inverter
Akai S900 Inverter

Finally, you solder the 14 pin connector on to the new display along with the P-401 wires to pins 15 and 16. Then you screw the LCD back into the front panel frame using small nuts to secure the LCD. Note that the LCD is a tad thicker so you have to screw the LCD behind the frame and not in front. That is why you need nuts to secure the LCD. You should know exactly what I mean once you see how your LCD is connected. Then you just power it on and all should work well. IF you should get a faded or partial lit LCD, then look for possible shorts connected to your soldering and the screws. The upper left hand screw is VERY close to the pin 15/16 solder joints. If you don’t solder that properly you may get a short.

Akai S900 OS 4.0 Disk
Akai S900 OS 4.0 Disk

In addition I was able to locate and make a copy of the Akai OS 4.0 software that pretty much brings the Akai S900 specs alongside that of the S950. I used an old Windows 98 PC along with Teledisk to make the copy to a DD floppy. It worked great.

I now have a pretty cool Akai S900 that both looks and works very well. If you are having LCD issues, I strongly recommend picking up some LCD screens from the seller mentioned above on Ebay. You’ll save a lot of money from the kits that are being sold if you can do it yourself. I basically figured out how to do this from my experience with changing my Yamaha SY-77 display. It was pretty much the same concept.

Please feel free to post questions if you like. Thanks!

10 thoughts on “Akai S900 Replacement LCD Display and OS Version 4

  1. elie

    Thanks for the great tip on where to find affordable displays, I have an old Roland D-550 and GP-8 that needs a new backlight/display so will check it out. Good to see that it’s not too difficult to DIY on changing and upgrading these older machines.

  2. Scott

    Thanks for the buydisplay.com tip. I was hoping the D-550 could use the ERM4002, is there anything you know that would suggest it can’t be used? Cheers, Scott

    1. Hi Scott,

      I think it’s possible it can be used. A couple things I need to look into are (1) will the screen actually fit in the D-550 dimension wise and (2) how to get the 5V power to the Backlight Anode.

      Pin 15 – LED_A Backlight Anode
      Pin 16 – LED_K Backlight Cathode

      On both the Yamaha SY-77 and Akai S900 there is a Power Inverter that can be removed. The 5V power to the inverter can then be diverted to the pin 15 Backlight Anode. I haven’t opened my D-550 to check about such a power source just yet.

      It is possible to perhaps just install the LCD and run no backlight which would mean having lit text against a black background which wouldn’t be that bad anyway. That would be far better than what I have now.

      I’ll check and update this post shortly. Thanks!

      1. Scott


        Thanks for the reply. I replaced the EL foil on my D550 a couple of weeks ago, the inverter buzz isn’t as bad as my SY77 but it is still annoying. In the D550 the inverter circuit is on the main power supply PCB. I imagine the simplest solution would be to cut traces on the PCB to remove the inverter circuit and solder a jumper to the 5V supply so the existing connector (CN2) can still be used. Cheers, Scott

  3. Guy

    I can’t see mention of a series resistor that you need to limit the current through the backlight, otherwise it’s life will be limited. Is the resistance of 27 to 33 ohms built into the display itself ?

  4. PJ

    Hey, thanks for the tip! I picked up an S900 here in NZ recently & need to replace backlight (as currently is dead) or upgrade to LED display, prefer the latter but kinda in the same place you were, eg eBay sellers to expensive (not including shipping to NZ on top). Was wondering is ERM4002 you purchased for yours?.. I gotta do the same for my Korg 01RW & my Akai MPC3000. Hard to find if you don’t know what upgrade LED model numbers are etc seems to be kept very quiet so the few people selling can make their coin from people like me/us etc 🙂

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