As it were, noone on the net has put up any inside pictures of either ER-1 or EA-1. So taking the matter in my own hands I carefuly taken my EA-1 appart to snag some images. With this information bending/modifying of these units may be possible.
Just from looking at the makings on the board it appears to be that ER-1 and EA-1 are very simular, and as a matter of fact possibly even interchangable! As seen in one of the images the ER-1 and EA-1 functions are separated by a single jumper on the board.
The extra output can been spotted by looking at the outside case.
By comparing the difference in knobs and the emply spots on the board. It appears that the waveform pot is missing from the EA-1 board. This would definatelly open up alot of potential in EA-1 giving it more then just saw, square, and ramp. The second missing knob is located in the place of the Delay depth spot on ER-1.
From one of the main DSP chips there is a wealth of jumpers leading to the memory chip located just above. Those jumpers are not used. I was told that the sound engine is the same as MS-2000. The same source was also right on the two DSP chips located inside of the unit.
It is not unheard of for companies to use the same boards and chipsets on different instruments and equipment. The other day I was reading about modding DVD players to make them better and adding Cartridge slots to the ATARI FLASHBACK 2.0. So I guess anything is possible, even modding EA-1 into an ER-1 or vise versa.
The next step is to aquire an ER-1 for more board shots. If my theory is true then all the parts present of EA-1 will be missing from the ER-1. Ofcourse there are the control interface differences, however those could be overcome with MIDI control, somehow.