Kawai R50 Custom Firmware

Features
– 16×1 OLED display support

Currently, the sole purpose of this firmware is to enable OLED support for the purposes of display replacement. Kawai R50 units with the stock display or LCD LED retrofits which use “8×2” addressing (faux 16×1) will not benefit from this firmware, as it is not an upgrade, per se, but rather an alternate build.

Installation

– Burn the custom firmware to a 27256 EPROM (no socket needed)
– Replace stock OS ROM with custom EPROM (drop-in replacement)
– Transplant the display header from the stock LCD to the OLED

Note: Although the dimensions (including thickness) of the OLED should be a perfect fit, the screw holes on the display will likely need to be enlarged slightly using a drill, dremel, file, or similar.

Potentially Supported OLEDs

Vishay 016N001ABPP5N0000 (blue) or O016N001AWPP5N0000 (white) via Mouser, U.S. distributor

Raystar REC001601ABPP5N00000 (blue) or REC001601AWPP5N00000 (white) via TME, European distributor

Winstar WEH001601ABPP5N00000 (blue) or WEH001601AWPP5N00000 (white) via Comet, Bulgarian distributor

Note: This list is not necessarily all-inclusive, nor guaranteed, but it is very likely all these displays will work.

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Troubleshooting

Problem: There is more noise in the audio than there was before the LCD to OLED swap.

Solution: This is very likely to do with the DC/DC converter boost circuitry used on the OLED. While OLED displays certainly look better, they often produce more noise than LCD. Try adding a 1000uF (or higher) capacitor across display pins 1 and 2. Make sure to observe the proper polarity (+ to 5V, – to ground) and to locate the capacitor as close as possible to the display. Due to the compact R50 case, physical space is limited, so placement is crucial; a capacitor with a small footprint is ideal.

If further noise suppression is desired, try adding an identical capacitor to the display connector on the mainboard side. Again: Space is limited.

On a similar note: The mainboard area near the resistor pack and the 7805 regulator appears to be very sensitive to noise and picking up interference. Specifically, C70 appears to act like an antenna, so adding a small RF shield in the area can remedy this. Make sure the shield is tied to ground, and that it has no exposed metal areas which could short nearby parts!

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