Hi folks,
I would like to add a couple of things about inverters and backlights, but first, to repeat MPCHunter - it is essential to have a decoupling capacitor in the circuit. Without that capacitor, you will introduce that noise right back into the MPC's power supply. From there it can and does leak into the audio. Personally I haven't tried to run an inverter without the decoupling cap in an MPC60 but I have tried it on other Akai samplers, with varying unpleasant noisy results. So please take the advice of MPCHunter.
Voltage
It is not usually a good idea to power an EL backlight with 233 volts. Please don't use an inverter with this sort of output, it is a little high. It does depend on a couple of other things but 233V is generally too high.
I have done extensive testing at varying voltages on EL panels, and above approximately 210V, the insulating material inside the panel can break down. It is very rare but it seems to begin around 210V. Microscopic flaws in this material at, say, 150V, will not usually cause a problem, and if they ever did, part of the backlight would simply 'go out' and that would be the extent of the problem. But at 233V, the breakdown is much more violent, a burn-hole or even a burn-line can appear which can melt through the protective layers of insulation on the backlight - this will not be good for your display.
(I test my EL material at high voltages with powerful inverters, to weed out any flaws. But I can't guarantee continued safe operation above 200V)
Voltage drop
Inverters' voltages will drop when you connect a backlight. The MPC60 inverter, which is approx 200V without a load, can drop to 100-120V or less with a backlight connected, this is normal.
Bigger inverters are designed for bigger EL panels. But this isn't always a good thing. Especially to be avoided are those very large inverters like the one in the last photo - *IF that inverter has a high voltage, say 150V or more*. This is because large inverters like that are designed to power huge panels, so their voltage does not fall when you connect an MPC60-size backlight. The backlight is operating at this high voltage all of its life.
Brightness and voltage
The higher the voltage when the backlight is connected, the brighter the backlight will be. But the backlight will have a shorter usable lifetime.
Frequency and brightness
EL backlights operate on AC currents of certain frequency. 400-800Hz is the usual operating frequency of most backlights. Higher frequency means more brightness. But again, there is a tradeoff, the usable lifetime is shorter at higher frequencies.
Very roughly, the best balance of brightness and lifetime for this type of EL backlight to be working at is around 90-120V, 400-600Hz.
Some inverters have extremely high frequencies of 2000Hz and more. Avoid them, they will shorten the usable lifetime.
If you fit an inverter and find that the backlight lights up your room and leaves a burn on your retina, it is going to have a shorter lifespan than is normal.
Be safe:
Please don't fit one of my backlights directly to an inverter that you are not sure about. If the inverter circuit is properly designed and tested, and outputs the correct power to the backlight, has the decoupling cap and short circuit protection, is mounted properly in your MPC, everything should be fine. I believe our own Jazzcat was looking into having his own inverter circuits produced, that are properly designed for the MPC60/60II.
If the backlight becomes a smouldering blob of molten plastic you may void your warranty
Akai might not honour their warranty either
Matt
