Fixing Roland JX-305

27/03/2016 UPDATE
I took apart my JX305 to replace the buttons (

as the old ones were a bit non responsive. These new ones are incredibly tactile and are quite stiff, but are new so they’re good! HOWEVER upon putting it all back together I got the dreaded blank LCD with the top row being all squares and the beat light being yellow.

Strange, I went to update the firmware using the Mute Ctrl + 3 method, but got the Flash ID err. Last time I reflowed ICs 7 and 8, but not IC1. I suspected it was IC1, so I physically pressed down IC1 while doing the firmware upgrade and I got to the next stage, but upon sending down the firmware, it would tell me Err! Low Voltage.

As I don’t have a hot air gun or SMD rework station, reflowing IC1 could be an issue. But I used a hair dryer on it for about 30 seconds on high heat, and now I could update it and now it works! Not sure how long it will last, a proper job needs the proper tools, but this will do for now…

Is your JX305 busted?
I’ve always wanted this “MC-505 in a Keyboard”. It’s like the MC505 with all it’s great sounds with an additional 4MB for Realistic Instruments such as Piano’s, EPs, Guitars, Strings so you can actually play some pop music.

Firstly the JX305’s suffered from a poor soldering technique. You’ll find that ‘IC1’ is the most likely to be faulty. You don’t need to replace it. You’ll just need to resolder/reflow the connections with a finetip soldering iron or a hot air gun.

If not IC1, then IC8 then IC7. You can tell if it’s IC1 because if you try to do a firmware upgrade, it will complain about a Flash ID error.

Secondly, the LCDs on the JX305 are pretty low quality. The carbon connectors weren’t really designed to last 15+ years, so the units out there in the field may be showing signs of missing lines/rows or columns on the LCD.

You can fix this by either getting a new LCD screen 16×2 off ebay or aliexpress or trying a hot clothing iron and running it across the carbon contacts. To do this you’ll need to unscrew the back cover and the CPU board before getting access to the LCD.

Once you’ve resoldered, upload the latest 1.07V firmware and perform a factory reset.

I’ve attached links to the Version 1.07 and Service notes/manuals below.

Hope all goes well, let me know how you get on. Note that Roland nor I cannot be responsible for any damage done to your unit by doing any modifications or updates.

QuickStart Guide!NY5gXADQ!tlSBjVIp8JgX3F088RdJ4mN2HFBQ2csMZey-6brGHwg

Service Notes!UdYASRyI!UXstxxAwSyZJmBD3WBaOWoE4bgBhsslyc2X2UH6MeSw

Full English Manual!ZARxmAja!DiwOVUuPKcwRb1sEgmeYndThT20b-DuJ3q5K08G6aAI

Version 1.05, 1.06 and 1.07 Updates!JFxj1RaA!dws3vGyemYiLWfJf0O7VY0nNxlc33CsIYyskFnYsops

11 thoughts on “Fixing Roland JX-305

  1. Great stuff. This is the only place I’ve found the 1.07 firmware available to thumbs up for that.
    I wanted to ask you some additional questions regarding the repair. Could you email me – or accept my Facebook request šŸ˜‰

  2. Great stuff! Very informative and almost makes me want to start playing around with it again. All jokes about the JX aside, it is a great moderate synth for its time. I’ve held onto mine since ’97. It’s survived years of gigs, bumps, shunts, getting dragged around and left in friends’ studios for months on end getting smoked around and jacked with and only suffered minor scrapes and minor hardware issues (like the Y-axis on the modulator no longer functioning). That being said, I won’t get rid of it. Aside from having a couple of pretty dank tunes stored in internal memory (The card slot no longer works properly) I now have a 15 month old that will probably enjoy playing around with it once he’s old enough.

  3. Hi mate!
    Had the exact same issue as you.
    Used a soldering iron on IC1 and then did the firmware update. Works like a charm now!!

    Thanx alot for this post. Was ready to give it up.. šŸ™‚

    //cheers from Sweden

  4. Dear Adrian,
    Thank you for sharing the info and files – very useful and practical. Just have got my JX and your tips are absolutely time saving.
    Best regards

    1. Hello,

      Please, Which length did you choose for the cable ?
      Does the FPC adapter require complicated soldering ?
      Do i need to order the LCD screen with or without the optionnal adapter displayed on your link ?
      Does this repair upgrade require to solder a resistor somewhere between the wires and the screen ?
      Thank you, and best regards.
      Hope you can help me.

  5. Hello, thank you everyone for your explanations, i’m about to order each part to repair my screen, but not being skiiled in electronics, i don’t know which 10kohm resistor i should buy, there are different powers, 1 watt, 2 watts, etc…Please can anyone give me some details about that resistor ? I have found those ones on ali express, but don’t know which ones to order ??,searchweb201602_,searchweb201603_,searchweb201602_,searchweb201603_

    Thank you for your help, hope someone can answer to me.
    Best regards.

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