We've had a couple Juno 60s in the shop recently. Both needed new RAM chips among
other things and consequently needed to have the factory sounds restored. We ordered a cassette copy and tried to load. No go. Kept getting the "Err" message. This customer actually found his factory original cassette and we tried it, but it didn't work either.
We downloaded a *.wav file version of the data and tried that using a cell phone for playback. Still got the error message. It was time to get a little deeper with the troubleshooting. I set up the scope and checked the signal coming into the microprocessor (IC14) at pin 1. There was plenty of data signal showing up. The cassette filters (IC22 and 23) had been replaced on panel board B and were doing their job of shaping the tape signals into square wave pulses.
This left me two options. Bad hardware or operator error. I decided to go with operator error. Signal level? Typical consumer cassette deck outputs -10dB at zero on the VU meter. I ran the cassette output through a small ART preamp, plugged that into my Leader 185 millivolt meter and dialed in -10dB. Press Play then Load on the Juno. Err again! This time immediately. Signal too hot? I dropped it to -15dB. I still got an Err message but at the end this time. I figured I'd check anyways. 56 patches!