I took apart my JX305 to replace the buttons (http://www.aliexpress.com/item/100PCS-2-pins-6-6-5-mm-Switch-Tactile-Push-Button-Switches-6x6x5mm-30624/32322935413.html)
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.
Full English Manual
Version 1.05, 1.06 and 1.07 Updates