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.

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.

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.

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.

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.

On 25/02/2017 14:28, 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.

no factory reset sequence found for this model. Reseated the socketed
memory JIC, but no change
As some of the function switches are out as well as keyboard, part of
same polling structure, i'll go with a problem on the digital side
rather than VCF/analogue. Continuity back to 40245 ok , but as 2 of the
octal lines out , presumably back farther than that, have to do some
digital probing after finding bench space.
One tip for dealing with these, small cable ties between top and base,
to act as a hinge for probing access to the internals and keep
everything in reasonable registration so no strained cables.

On 02/28/2017 06:46 AM, N_Cook wrote:
On 25/02/2017 14:28, 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.

no factory reset sequence found for this model. Reseated the socketed
memory JIC, but no change
As some of the function switches are out as well as keyboard, part of
same polling structure, i'll go with a problem on the digital side
rather than VCF/analogue. Continuity back to 40245 ok , but as 2 of the
octal lines out , presumably back farther than that, have to do some
digital probing after finding bench space.
One tip for dealing with these, small cable ties between top and base,
to act as a hinge for probing access to the internals and keep
everything in reasonable registration so no strained cables.

My Alpha Juno 2 from around the same timeframe had a problem with the
membrane switches on the front panel not activating correctly; I traced
it down to a bad pullup resistor in one of the SIP packages attached to
the bus headed from the switch board to the demultiplexer IIRC.

Might be worth looking at too...

On 08/03/2017 03:40, bitrex wrote:
On 02/28/2017 06:46 AM, N_Cook wrote:
On 25/02/2017 14:28, 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.

no factory reset sequence found for this model. Reseated the socketed
memory JIC, but no change
As some of the function switches are out as well as keyboard, part of
same polling structure, i'll go with a problem on the digital side
rather than VCF/analogue. Continuity back to 40245 ok , but as 2 of the
octal lines out , presumably back farther than that, have to do some
digital probing after finding bench space.
One tip for dealing with these, small cable ties between top and base,
to act as a hinge for probing access to the internals and keep
everything in reasonable registration so no strained cables.

My Alpha Juno 2 from around the same timeframe had a problem with the
membrane switches on the front panel not activating correctly; I traced
it down to a bad pullup resistor in one of the SIP packages attached to
the bus headed from the switch board to the demultiplexer IIRC.

Might be worth looking at too...



That makes sense, for losing a third set of keys, as in the process of
probing the 40245 I bent the data bus SIP R more vertical slightly, to
give a gap, as was leaning against that side of the IC.
But otherwise I don't remember having come across a failed SIP R pack.

Replaced TC40H245P with 74HC245 and all keys now working.
Cold DVM-D test of the old 245, to either supply pin, showed no forward
drop in any direction, to the gates used by D5,D6,D7 unlike to the other
pins.
Some of the front panel switches came back to life but switches 1 to 8
of 16 bank, no function or Midi LED flash. Hopefully just failed
"ribbon" 33 yearold age hardened copper wire that gave up the ghost with
all this unaccostomed flexing of connecting and disconnecting the main pcb.

Must have been sat on or similar, to squash area near sw16, down onto
the ps h/s and cracked the pcb.
There is a H&S factor with these, bad enough that main pcb is secured to
chipboard base by wood screws, so loosish screws that could fall away.
But the mains carrying pcb is also just woodscrewed to the chipboard as
well.