New here ...

Yamaha PSR-12, has maybe 72 keys, around 24 voicings, flexible-speed
percussion, canned tunes, etc. About 20 years old.

I turn it on lately, it works fine for 2-10 min., then freezes.
The little light that is supposed to come on for beat 1 (when
percussion accompaniment is running) locks on. That and the power led
are the only things functional.

The case has 2 halves. I workbench the thing turning the business
end (with keys and most PCB's) up 90 degrees to tinker, and it plays OK
for up to 3 hours (presumably lots longer). I figured the problem
has to do with either gravity or heat buildup, but I just left it
normally assembled and on for several hours and it didn't freeze up,
so maybe heat isn't the problem.

There are PCB's for power and switching, and 2 big PCB's presumably
for tone generation, special effects, etc. I tried some ribbon
cable connections: wouldn't budge. I'm afraid of breaking a
board or connector or ?.

It's gotta be repairable. I think. :-)

Any/all help/advice much appreciated.

Thx,
Puddin'

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

"Puddin' Man" wrote in message
...

New here ...

Yamaha PSR-12, has maybe 72 keys, around 24 voicings, flexible-speed
percussion, canned tunes, etc. About 20 years old.

I turn it on lately, it works fine for 2-10 min., then freezes.
The little light that is supposed to come on for beat 1 (when
percussion accompaniment is running) locks on. That and the power led
are the only things functional.

The case has 2 halves. I workbench the thing turning the business
end (with keys and most PCB's) up 90 degrees to tinker, and it plays OK
for up to 3 hours (presumably lots longer). I figured the problem
has to do with either gravity or heat buildup, but I just left it
normally assembled and on for several hours and it didn't freeze up,
so maybe heat isn't the problem.

There are PCB's for power and switching, and 2 big PCB's presumably
for tone generation, special effects, etc. I tried some ribbon
cable connections: wouldn't budge. I'm afraid of breaking a
board or connector or ?.

It's gotta be repairable. I think. :-)

Any/all help/advice much appreciated.

Thx,
Puddin'


Stuff with micros locking up, often is a heat problem to do with the power
supply, especially if the item really is 20 years old, and more especially,
if it makes use of a switchmode power supply. As a first move, I would feel
inclined to pop a meter on the main 5v rail, and see where it's at, then
leave it on there, and see if it's any different, when the unit locks up. A
'scope on there wouldn't hurt as well. The rail should ideally be no lower
than about 4.85v and no higher than about 5.2v. The 'official' limits are a
little wider than that, but it won't have been designed to run outside of
the limits I've said. The rail should also be 'clean' with hash or ripple no
higher than say 20mV.

If there are any issues with voltage level or noise, look to caps and
resistors in the regulator circuit, for your trouble.

If the power supply turns out to be ok, the next place I would turn my
attention, is to the system control processor's clock crystal. Old xtals
sometimes get reluctant to oscillate, and will just stop after a short
while, in just the way you describe. You can often 'prove the point' by
taking the xtal out, and refitting it reveresed to its original orientation.

Finally, I have a dim recollection of a keyboard having a problem like this,
some years ago. As I recall, it too had a couple of large logic boards, and
ribbon style interconnects looping the boards and power supply together. The
'launch' level of the power supply was fine at 5v, but by the time it
reached the second board, having passed through tracks from one end of the
board to the other, and the in and out board connectors, it had dropped to
perhaps 4.8v, due no doubt to age-deterioration of the connector plating,
and the large current that all this logic draws on the older stuff. Anyway,
it was enough to cause the thing to keep locking up. Eventually, I decided
that there was no particular need for the supply to the furthest board to
loop through the nearest one, so I gave it its own heavy gauge wires
straight back to the power supply, which cleared up its problems completely.

Arfa

Arfa Daily wrote:
"Puddin' Man" wrote in message
...
New here ...

Yamaha PSR-12, has maybe 72 keys, around 24 voicings, flexible-speed
percussion, canned tunes, etc. About 20 years old.

I turn it on lately, it works fine for 2-10 min., then freezes.
The little light that is supposed to come on for beat 1 (when
percussion accompaniment is running) locks on. That and the power led
are the only things functional.

The case has 2 halves. I workbench the thing turning the business
end (with keys and most PCB's) up 90 degrees to tinker, and it plays OK
for up to 3 hours (presumably lots longer). I figured the problem
has to do with either gravity or heat buildup, but I just left it
normally assembled and on for several hours and it didn't freeze up,
so maybe heat isn't the problem.

There are PCB's for power and switching, and 2 big PCB's presumably
for tone generation, special effects, etc. I tried some ribbon
cable connections: wouldn't budge. I'm afraid of breaking a
board or connector or ?.

It's gotta be repairable. I think. :-)

Any/all help/advice much appreciated.

Thx,
Puddin'


Stuff with micros locking up, often is a heat problem to do with the power
supply, especially if the item really is 20 years old, and more especially,
if it makes use of a switchmode power supply. As a first move, I would feel
inclined to pop a meter on the main 5v rail, and see where it's at, then
leave it on there, and see if it's any different, when the unit locks up. A
'scope on there wouldn't hurt as well. The rail should ideally be no lower
than about 4.85v and no higher than about 5.2v. The 'official' limits are a
little wider than that, but it won't have been designed to run outside of
the limits I've said. The rail should also be 'clean' with hash or ripple no
higher than say 20mV.

If there are any issues with voltage level or noise, look to caps and
resistors in the regulator circuit, for your trouble.

If the power supply turns out to be ok, the next place I would turn my
attention, is to the system control processor's clock crystal. Old xtals
sometimes get reluctant to oscillate, and will just stop after a short
while, in just the way you describe. You can often 'prove the point' by
taking the xtal out, and refitting it reveresed to its original orientation.

Finally, I have a dim recollection of a keyboard having a problem like this,
some years ago. As I recall, it too had a couple of large logic boards, and
ribbon style interconnects looping the boards and power supply together. The
'launch' level of the power supply was fine at 5v, but by the time it
reached the second board, having passed through tracks from one end of the
board to the other, and the in and out board connectors, it had dropped to
perhaps 4.8v, due no doubt to age-deterioration of the connector plating,
and the large current that all this logic draws on the older stuff. Anyway,
it was enough to cause the thing to keep locking up. Eventually, I decided
that there was no particular need for the supply to the furthest board to
loop through the nearest one, so I gave it its own heavy gauge wires
straight back to the power supply, which cleared up its problems completely.

Arfa


It`s just possible that a reset to factory settings might help[1].
There`s a list of Yamaha reset procedures here
http://www.yamaha-europe.com/yamaha_...ist/index.html

I dont see one for the PSR-12 but it`s possible that one of the other
PSR resets would work.

[1] It`s a long shot but it might work!

Ron(UK)

On Wed, 12 Dec 2007 11:16:07 +0000, "Ron(UK)" wrote:

It`s just possible that a reset to factory settings might help[1].
There`s a list of Yamaha reset procedures here
http://www.yamaha-europe.com/yamaha_...ist/index.html

I dont see one for the PSR-12 but it`s possible that one of the other
PSR resets would work.

[1] It`s a long shot but it might work!

Anything's worth a shot.

But I'm having trouble interpreting such as:

PSR220 Press [+/YES], [-1/NO] + Power on

There's no +, -, YES, NO on the keyboard. There are 2
pairs of buttons with only up/down settings: pitch and
beat. When the unit freezes, these buttons have no
effect.

Thx,
P

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

On Wed, 12 Dec 2007 09:33:11 GMT, "Arfa Daily" wrote:

Stuff with micros locking up, often is a heat problem to do with the power
supply, especially if the item really is 20 years old, and more especially,
if it makes use of a switchmode power supply. As a first move, I would feel
inclined to pop a meter on the main 5v rail, and see where it's at, then
leave it on there, and see if it's any different, when the unit locks up. A
'scope on there wouldn't hurt as well. The rail should ideally be no lower
than about 4.85v and no higher than about 5.2v. The 'official' limits are a
little wider than that, but it won't have been designed to run outside of
the limits I've said. The rail should also be 'clean' with hash or ripple no
higher than say 20mV.

Here's some additional info:

The specs say "rated voltage - 9v dc".

I have only 19 yr-old $10 meter. I don't expect accuracy, but rather
ballpark readings.

Directly from the 120v converter connector, it *looks* like 15v dc.

The switch/volume board has a 2 element wire that appears to feed
the 2 main boards. There I measure 2v dc both with the unit
functionaing -and- when it is frozen.

Did that make any sense?

Thanks,
P

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

Puddin' Man wrote:
On Wed, 12 Dec 2007 09:33:11 GMT, "Arfa Daily" wrote:

Stuff with micros locking up, often is a heat problem to do with the power
supply, especially if the item really is 20 years old, and more especially,
if it makes use of a switchmode power supply. As a first move, I would feel
inclined to pop a meter on the main 5v rail, and see where it's at, then
leave it on there, and see if it's any different, when the unit locks up. A
'scope on there wouldn't hurt as well. The rail should ideally be no lower
than about 4.85v and no higher than about 5.2v. The 'official' limits are a
little wider than that, but it won't have been designed to run outside of
the limits I've said. The rail should also be 'clean' with hash or ripple no
higher than say 20mV.

Here's some additional info:

The specs say "rated voltage - 9v dc".

I have only 19 yr-old $10 meter. I don't expect accuracy, but rather
ballpark readings.

Directly from the 120v converter connector, it *looks* like 15v dc.

The switch/volume board has a 2 element wire that appears to feed
the 2 main boards. There I measure 2v dc both with the unit
functionaing -and- when it is frozen.

Did that make any sense?

Yes...and no. The 2 volt reading is meaningless unless you can
determine that it was measured at the point where supply voltage enters
that particular board. There might be some sort of marking at the
terminal...perhaps "+5v" or "B+" or "Vcc". That the voltage does not
change when frozen is irrelevant.

That said, if it *is* the main supply terminal, it is probably low, and
the unit is just barely limping along with reduced voltage even when
functioning.

The 15vdc reading from the 'unloaded' (IOW not connected to anything)
supply is also irrelevant. The relevant reading is taken when the
supply is actually supplying current to the keyboard.

You need to find the main power supply board, and trace forward from
where there. That board (or portion of the main circuit board where the
DC adapter connects) is where the excess voltage is regulated down to a
level that the actual circuits use.

jak
Thanks,
P

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

On Wed, 12 Dec 2007 15:42:10 -0600, jakdedert wrote:

You need to find the main power supply board, and trace forward from
where there. That board (or portion of the main circuit board where the
DC adapter connects) is where the excess voltage is regulated down to a
level that the actual circuits use.

Power supply board:
Takes input from batt. or converter
Connections:
Black wire - screws to alum. kb frame
"to HP" - 3 element, goes to speaker
"to DM" - 4 element, goes to 1684 PN1 (lg. board)
elements are labeled DG +5D AG +5A
+5D and +5A measure 5v DC to black wire
"to SW" - 8 element, goes to switch/volume board
elements are labeled E 5v B T M S E E
M measures 15v DC to black wire

The two large boards (2 x 12+ ") are labeled 1684 PN1 and 1684 PN2
with markings for the voicings, various effects.

Any help?

Thx,
P

"Well, there's two trains runnin'.
Ain't neither one goin' my way.
One run at midnight,
the other run just before day."
- from "Still A Fool", Muddy Waters, maybe 1949

"Puddin' Man" wrote in message
...
On Wed, 12 Dec 2007 15:42:10 -0600, jakdedert
wrote:

You need to find the main power supply board, and trace forward from
where there. That board (or portion of the main circuit board where the
DC adapter connects) is where the excess voltage is regulated down to a
level that the actual circuits use.

Power supply board:
Takes input from batt. or converter
Connections:
Black wire - screws to alum. kb frame
"to HP" - 3 element, goes to speaker
"to DM" - 4 element, goes to 1684 PN1 (lg. board)
elements are labeled DG +5D AG +5A
+5D and +5A measure 5v DC to black wire
"to SW" - 8 element, goes to switch/volume board
elements are labeled E 5v B T M S E E
M measures 15v DC to black wire

The two large boards (2 x 12+ ") are labeled 1684 PN1 and 1684 PN2
with markings for the voicings, various effects.

Any help?

Thx,
P


"+5D" will be the 5v digital supply - ie the 5v supply for the digital
electronics, and "+5A" will be the 5v analogue supply. "DG" and "AG" are the
corresponding digital and analogue ground returns for those two supplies, so
will be the references to measure the supplies against. You really need to
be able to measure the +5D supply with a reasonable amount of accuracy - to
at least 0.05v.

Arfa