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 02/25/2017 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 02/27/2017 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.

Old removed, tuned pin 20w socket , in place, easier to check continuity
etc, finish that tomorrow and push in NOS LS373.
Loads of black corrossion product on the pins of this IC and only this
one , no other TTL,4000 or analogue, whatever that means, outgassing
something ?. Cracked it open and frame metal was clean on the internal
pins I could see where free of encapsulant.
Texas Instruments, SN74LS373N, Malaysia 8206X if a batch problem.

N_Cook wrote:

Old removed, tuned pin 20w socket , in place, easier to check continuity
etc, finish that tomorrow and push in NOS LS373.
Loads of black corrossion product on the pins of this IC and only this
one , no other TTL,4000 or analogue, whatever that means, outgassing
something ?. Cracked it open and frame metal was clean on the internal
pins I could see where free of encapsulant.
Texas Instruments, SN74LS373N, Malaysia 8206X if a batch problem.
Well, not clear if the original chip was in a socket.

There was a certain vintage of TI chips that had a silver plating that could
turn absolutely BLACK! These could certainly cause bad contacts in sockets,
but I think I've seen a couple times where it was so bad it got down and
isolated the pin from the through-hole in the board. I thought these were
before 1982, back in the mid-late 70's or so, but must have still been doing
that plating later. I'm pretty sure it didn't come from inside the chip,
but the effect of atmospheric sulfur on the silver plating.

Jon

All that pallaver of swapping corroded 74LS373 (but good) and I'm back
to loss of Data5 and Data7 keys but now D6 keys gone west also,
continuity checks out fine and should be there as before.
D0 to D7, correspond to keys 1 to 8 of each octet of keys, not octave.
So went back to original plan, but now with no D6 to swap to D7.
So cut the trace to D3 input of the 40245 keyboard scan IC and fed the
D7 line to that pin. Powering up, the 4th key of each batch of 8 now
sounded at the pitch of "7" not "3" and midi LED flashed.
So looks like swapping out the 40245, I think, but perhaps wrong, as it
seems functioning correct signal on D7 line but not getting through the
40245 nor D6 nor D5, input to outputs , for keybd scan.
Pitch number 8 of each octet would sound (and 6 and now 5) , if the
keyboard scanning funtion was working correctly, I hope.

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.

Before I got to this, an electrician had removed all the keys without
some sort of sequence marking, so I ended up with a carrir bag of them.
I assumed out there, via google bunging in
roland keyboard keys, CF1,EB2,CF, D, A ,G , C ,23
someone would have put out there the sequence required to lay up a
Roland keyboard moulded with those cryptic alphanumerics, but apparently
not. Any pics I've found is ambiguous as the degree of left and right
throws on the white keys, let alone the unseen pivot slot widths that vary.
C D E F G A B C is not very helpful

On 08/03/2017 16:04, N_Cook wrote:
Before I got to this, an electrician had removed all the keys without
some sort of sequence marking, so I ended up with a carrir bag of them.
I assumed out there, via google bunging in
roland keyboard keys, CF1,EB2,CF, D, A ,G , C ,23
someone would have put out there the sequence required to lay up a
Roland keyboard moulded with those cryptic alphanumerics, but apparently
not. Any pics I've found is ambiguous as the degree of left and right
throws on the white keys, let alone the unseen pivot slot widths that vary.
C D E F G A B C is not very helpful

Looking at an old Casio keyboard, for white keys the direction of throws
at the leading edge is, per octave
CDEFGAB
right,double equal,left,right, double biased R, double biased L, L

The Roland moulding number sequence of each octave is
EB2,CF1,D,EB2,CF1,G,A,EB2
top C is CF and black notes 23

Lay out the white keys , just laying on the top, mark the pivots that
take the black keys, remove the white keys, set all the black keys in ,
then all the white keys, finally set the springs on with a hook. holding
the fixed static end with a finger to avoid the spring flying off