Hi, all -
Ok, I have found this the hard way. I have a very old Roland EP-7 that I bought used many years ago. I had it stored in the garage for more than a decade. The other day, I dragged it in and disassembled it and discovered that a bunch of the key weights had dropped off, etc. The now-familiar syndrome. The only slight variation from what others describe is that what everyone refers to as red or pink epoxy to me looks brown. Fiddling around (before I googled it), I found that the glue more or less melted upon heating it with a hair dryer. I have not gone to the effort of taking it all apart, cleaning every key and regluing with something presumably longer lasting (?) Rather, I just reset the missing weights and kind of melted them back into place with the hair dryer. Then I realized that a lot of the stuff running down was sticking keys together, etc. So I got the keyboard out and started disassembling keys and cleaning the excess glue off the sides of the keys by applying a little heat from the hair dryer and isopropyl alcohol on swabs once the glue softened. Put it all back together. Now, I should have powered up the keyboard before opening it! But I couldn't find the power supply for a day or two. Finally I did - in the garage a few feet away from where the keyboard had been for the past decade - and *then* tried the keyboard. It works - sort of. Specifically, of the 76 notes, all but a consecutive run of 22 of them work perfectly! The lowest 46 notes all work correctly, then from notes 47 to 68, inclusive, none work at all. No sound. Then the top 8 notes work fine. The problem is not with the synthesizer, in that the demo (Chopin Minute waltz excerpt) plays perfectly, including a lot of notes in the run of 22 non-functioning keys.
The brain-teaser about this is how could it possibly be that set of consecutive keys that don't work at all, in that the boundaries of that bad run do not correlate with anything? The boundary between the two contact boards is between notes 32 and 33 (i.e., the lower board has the first 32 notes, the upper board has the remaining 44). The matrix looks like it's in groups of 8 notes starting with the lowest note, and the uppermost group uses 4 notes (notes 73-76 inclusive), so that neither the lower nor the upper boundaries are between groups. It's not a question of getting one of the two ribbon connectors that go into the main board seated correctly, in that I have disconnected first one then the other and it's not a question of one of them not being connected. I did a factory reset in case it was some weirdness that could be fixed like that, to no effect. (Press REC and PLAY simultaneously, then press STRINGS, then power off and back on again.) I guess if nobody has a suggestion, I will take off all of the keys in that run and carefully inspect the contact boards and the rubber sheets (oh, another lack of correlation is that the rubber sheets are, starting at the bass end, 1 group of 8 notes, followed by 5 groups of 12 notes, then 1 of 8 notes - so the upper boundary is correlated with the start of the highest contact rubber sheet, but the lower boundary is not, because 22 is not a multiple of 12!) But I cannot see how there could be anything wrong with these things that would cause this exact symptom. Can anyone here?
Thanks for any advice and/or insight anyone can provide!
Bob P. in San Diego