On 02/27/2017 12:55 AM, bitrex wrote:
On 02/25/2017 09:28 AM, N_Cook wrote:
Stored indoors for some years and then powering up, missing notes and
some top panel sw functions missing.
full sm here
http://www.synfo.nl/servicemanuals/R...VICE_NOTES.pdf
same 2 notes ,not each octave , but as keyboard is scanned as 8x8 matrix
keys 8n and 8n-2 are missing , n= 1 to 8.
Hopefully that means the 74LS138 3 to 8 demultiplexer did not survive
1/3 century,internal metalisation creep or something, rather than main
micro problem.

Did you try doing a factory configuration reset? These old Rolands use a
battery backed SRAM to store both patch data and for the system
scratchpad RAM, if it gets corrupted you can get all sorts of problems
like the ones you describe.

That is to say it stores front-panel settings etc. in the battery backed
RAM during power-down, and if they get corrupted to garbage values the
keyboard stops triggering correctly, etc.