From left to right: ground terminal, captive mains lead, ID plate, Delay time pot x1 to x1.5, Modulation CV input jack 0 - 5 volts, Preset shift control input jack, "Play Mate" control input jack, Hold on/off control input jack, Delay on/off control input jack, Delay audio output jack, Mixed audio output jack, "Unigain" switch for input and output levels, Audio input jack.
The Delay Time pot directly affects the VCO in charge of the master clock pulses to the main controller. For some reason, turning this up will increase the unit's tendency to go into nasty high frequency oscillation at high feedback levels. Also, the quality of the delay signal is noticeably better at lower settings. Moving this pot will affect the time of the 4 programs.
The Modulation Foot Control has 5 volts available to directly control delay time via a pot or a volume pedal, or you can send it 0 - 5 volts from another source. This can be scaled from the front panel Mod pot. Unfortunately the range of the external control is somewhat underwhelming.
The Preset Shift jack takes a momentary switch/footswitch to step through the four programmable presets. This would seem to give scope for some creative program changing. Say for example, to enhance a rhythm track, you could have different preset resonant flange effects synchronised with the beat. Unfortunately, Roland put a spanner in the works there, by getting the CPU to mute the delay output every time a preset is changed (this muting also occurs when the delay time is changed from the front panel, and is there to suppress glitches. The glitches, for me, are often where the happy accidents occur). Looking at the schematic, I identified the line from the CPU to the logic that controlled this muting. I disconnected the CPU pin, and tied the logic side to 5 volts, disabling this "feature" (without disabling the power-on mute etc).
The "Play Mate" footswitch function, on first tap, resets the display to all zeroes, then the following two taps allows the CPU to calculate the time between them and set that as the delay time, i.e. tap tempo.
The Hold jack takes a footswitch, and plays the contents of the memory over and over, uninfluenced by front panel control except, happily, the Timex2 switch.
The Delay on/off switch is very handy for external sequencer control, especially in high feedback scenarios - you can chop it rhythmically! Note there is no corresponding front panel control for this.
The Delay output jack obviously just has the delay signal on it. When a plug is inserted here, the delay signal is switched out from the Mixed output, leaving just the dry signal, for those live "stereo" configurations.
The audio input can take line or guitar level signals. The pre-amp is a push-pull emitter follower type with a gain of about x24.
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