Ok, so after looking at the K5 service manual, the LCD we have in the K5 should be a Toshiba TLC-711A-E0.
A little reading online seems to tell that the TLX-711A-E0 LCD module is an identical replacement and we have the datasheet here :
Which shows that the new panel from Futurlec would be a suitable replacement with LED backlight. Of course, the voltages aren't the same. The original EL backlight works at 130V 1kHz while the LED is working at 4.1V.
Most of the time, the inverter in the K5 dies before the EL backlight, due to cold solder joints in the epoxy-filled inverter (good luck trying to fix it).
But even if you spend around 20$ + shipping for a new inverter, the EL foil will often be very close to it's end of life, so you'll spend another 30$ +shipping to fix this.
As Mo just said, if you email backlightsonline.com
, they'll have a replacement backlight foil for you. (Altough I don't know if it's LED or EL based.)
Now, the only two known inverters that are within specs for a new backlight are the NDL-205 and NDL-206 from JKL Components. The 205 is a little low on output voltage (90V) so it probably won't come out as bright as it should be. The 206 is a more suitable replacement (120V output), but seems to be a custom order everywhere I looked.
The LCD module at Futurlec sounds promising to me as LEDs have a much longer lifespan compared to EL backlights, and we could just replace the inverter by one or two resistors to get the 4.1V required. There is a blue on black version available as well if some would prefer
However, I haven't tried this particular LED-backlit LCD, but generally speaking, a fresh EL backlight provides a very uniform and bright display, while LEDs make bright spots all around the display. Another thing you'd lose is the good 'ol K5 whine coming from the inverter.
I'll probably give the LED display a try eventually and tell you if it's a viable option.