This is an "out of curiosity" question. I have multiple backups of this unit,
and //do not// intend to repair it. I just want to see if anyone has any
interesting insights.

The unit is a D-FJ75TR, one of Sony's last "deluxe" Discmans. I'd been using
it to listen to CDs in bed, and yesterday it stopped working correctly.

When I install the batteries, or plug it into the adapter, it immediately
starts to play -- and none of the controls work. I can't pause it, change the
track, set the volume, etc. Nor do any of the controls on the remote/tuner
module work. (Unplugging the remote doesn't fix the problem. And the control
lock button isn't jammed.)

The "obvious" answer is CMOS lockup, which I've seen on other products.
Yanking the power while the device is running sometimes cures this, but not in
this case.

I'm not trying to start an extended, overwrought discussion. I'm just
wondering if anyone has any ideas.

Thanks.

On 30/11/2014 18:40, William Sommerwerck wrote:
This is an "out of curiosity" question. I have multiple backups of this
unit, and //do not// intend to repair it. I just want to see if anyone
has any interesting insights.

The unit is a D-FJ75TR, one of Sony's last "deluxe" Discmans. I'd been
using it to listen to CDs in bed, and yesterday it stopped working
correctly.

When I install the batteries, or plug it into the adapter, it
immediately starts to play -- and none of the controls work. I can't
pause it, change the track, set the volume, etc. Nor do any of the
controls on the remote/tuner module work. (Unplugging the remote doesn't
fix the problem. And the control lock button isn't jammed.)

The "obvious" answer is CMOS lockup, which I've seen on other products.
Yanking the power while the device is running sometimes cures this, but
not in this case.

I'm not trying to start an extended, overwrought discussion. I'm just
wondering if anyone has any ideas.

Thanks.

stuck contact of a key?

Stuck contact of a key?

The obvious one would be the Play button (as the unit starts playing when I
put the batteries in).

I'll try holding down the Play button on a "good" unit, and see what happens.

Some models had a "lock" switch to keep random hits from affecting the play while one is jogging or something.

HAHAHA, Sony thought people in this country jog !

"N_Cook" wrote in message ...

On 30/11/2014 18:40, William Sommerwerck wrote:
This is an "out of curiosity" question. I have multiple backups of this
unit, and //do not// intend to repair it. I just want to see if anyone
has any interesting insights.

The unit is a D-FJ75TR, one of Sony's last "deluxe" Discmans. I'd been
using it to listen to CDs in bed, and yesterday it stopped working
correctly.

When I install the batteries, or plug it into the adapter, it
immediately starts to play -- and none of the controls work. I can't
pause it, change the track, set the volume, etc. Nor do any of the
controls on the remote/tuner module work. (Unplugging the remote doesn't
fix the problem. And the control lock button isn't jammed.)

The "obvious" answer is CMOS lockup, which I've seen on other products.
Yanking the power while the device is running sometimes cures this, but
not in this case.

I'm not trying to start an extended, overwrought discussion. I'm just
wondering if anyone has any ideas.

Thanks.

stuck contact of a key?




I thought so too.


Gareth.

When the Play/Pause button is held down, a "good" unit misbehaves in exactly
the same way as the "bad" unit, whether or not the remote control is
installed.

The Play/Pause button isn't jammed, so it would seem the fault is somewhere in
the wiring.

I have the service manual. When I find it, I'll tear into the lid (which holds
the key pad). It couldn't hurt.

"William Sommerwerck" wrote in message
...
When the Play/Pause button is held down, a "good" unit misbehaves in
exactly the same way as the "bad" unit, whether or not the remote control
is installed.

The Play/Pause button isn't jammed, so it would seem the fault is
somewhere in the wiring.

I have the service manual. When I find it, I'll tear into the lid (which
holds the key pad). It couldn't hurt.


Assuming that it's one of the tactile 'dome' switches, it is very common for
these to 'collapse' and effectively fail short circuit. I know that you said
you were not looking to repair it, but it really is a very simple fix if you
can be bothered to take it apart.

Arfa

Assuming that it's one of the tactile 'dome' switches, it is very common for
these to 'collapse' and effectively fail short circuit. I know that you said
you were not looking to repair it, but it really is a very simple fix if you
can be bothered to take it apart.

Arfa

He said it wasn't collapsed, although there's the possibility some liquid was spilled in the key matrix and is causing an unintended function command.

But I've seen a few of these over the years where the scan lines can be unsoldered at the micro for a test and the fault remains. Sometimes it's a bad micro caused by a static discharge through the control board.

"John-Del" wrote in message
...


Assuming that it's one of the tactile 'dome' switches, it is very common
for
these to 'collapse' and effectively fail short circuit. I know that you
said
you were not looking to repair it, but it really is a very simple fix if
you
can be bothered to take it apart.

Arfa

He said it wasn't collapsed, although there's the possibility some liquid
was spilled in the key matrix and is causing an unintended function
command.

But I've seen a few of these over the years where the scan lines can be
unsoldered at the micro for a test and the fault remains. Sometimes it's
a bad micro caused by a static discharge through the control board.




I had a piano keyboard once that had lost some notes.
It turned out the scan IC scanned both the keys and the button/LED matrix
using part of the same bus. One LED was short circuited, which disabled one
line shared with the keys, taking out the whole bunch of notes.



Gareth.

"Arfa Daily" wrote in message ...

Assuming that it's one of the tactile 'dome' switches, it is very common
for these to 'collapse' and effectively fail short circuit. I know that you
said you were not looking to repair it, but it really is a very simple fix
if you can be bothered to take it apart.

It's not a question of "bothered". I have to find the service manual so I can
"rationally" remove the lid. (It's not obvious how it comes off.) Once that's
done, it will be a simple matter to unscrew the panel covering the switch pad.

Thanks for your encouragement. Now, if I can get some help with the Lux
amplifier I damaged yesterday... (There's always John Curl.)

"John-Del" wrote in message
...


Assuming that it's one of the tactile 'dome' switches, it is very common
for
these to 'collapse' and effectively fail short circuit. I know that you
said
you were not looking to repair it, but it really is a very simple fix if
you
can be bothered to take it apart.

Arfa

He said it wasn't collapsed, although there's the possibility some liquid
was spilled in the key matrix and is causing an unintended function
command.


Err, no he didn't. He said it wasn't jammed, which is an entirely different
thing. I replace many many of these buttons on a variety of equipment that
uses them, and it is not at all uncommon for the dome to collapse, whilst
the outer control button remains free to move.



But I've seen a few of these over the years where the scan lines can be
unsoldered at the micro for a test and the fault remains. Sometimes it's
a bad micro caused by a static discharge through the control board.


I've had one or two failed micros over the years, but compared to faulty
switches, the relative proportion is vanishingly small

Arfa

On Monday, December 1, 2014 8:23:21 PM UTC-5, Arfa Daily wrote:

He said it wasn't collapsed, although there's the possibility some liquid
was spilled in the key matrix and is causing an unintended function
command.


Err, no he didn't. He said it wasn't jammed, which is an entirely different
thing. I replace many many of these buttons on a variety of equipment that
uses them, and it is not at all uncommon for the dome to collapse, whilst
the outer control button remains free to move.

If you're talking to a customer on the phone and they say it isn't jammed, it's possible the switch collapsed and they can't tell the difference. But Mr. S is clearly no newbie. If he says it's not jammed, it's a fairly safe assumption that the tactile feedback of his play button is the same as the rest of the buttons on the machine.

"Arfa Daily" wrote in message ...

I've had one or two failed micros over the years, but compared to faulty
switches, the relative proportion is vanishingly small.

As soon as I find the service manual (which I will be looking for this
morning), I will let you guys know. (I'm sure you're waiting with bated
breath.)

Practical servicing question, Arfa... If I'm soldering in a CMOS-based device
that's battery-operated, would it make sense to leave the batteries in, on the
(likely faulty) assumption they would supply a low-impedance path for errant
voltages?

Of course not! I shouldn't have written that! I'm making a fool of myself!

"William Sommerwerck" wrote in message
...
"Arfa Daily" wrote in message ...

I've had one or two failed micros over the years, but compared to faulty
switches, the relative proportion is vanishingly small.

As soon as I find the service manual (which I will be looking for this
morning), I will let you guys know. (I'm sure you're waiting with bated
breath.)

Practical servicing question, Arfa... If I'm soldering in a CMOS-based
device that's battery-operated, would it make sense to leave the batteries
in, on the (likely faulty) assumption they would supply a low-impedance
path for errant voltages?

Of course not! I shouldn't have written that! I'm making a fool of myself!


Personally, I never leave batteries in anything that I'm working on with a
soldering iron. Just employ normal good workshop practice of having a
resistively grounded wrist strap to a conductive bench mat. In my
experience, the chances of damaging CMOS inputs these days is very small,
given that they pretty much universally have protection diodes fabbed into
the chip, and usually some external R, positioned close to the chip.

Arfa

"John-Del" wrote in message
...
On Monday, December 1, 2014 8:23:21 PM UTC-5, Arfa Daily wrote:

He said it wasn't collapsed, although there's the possibility some
liquid
was spilled in the key matrix and is causing an unintended function
command.


Err, no he didn't. He said it wasn't jammed, which is an entirely
different
thing. I replace many many of these buttons on a variety of equipment
that
uses them, and it is not at all uncommon for the dome to collapse, whilst
the outer control button remains free to move.

If you're talking to a customer on the phone and they say it isn't jammed,
it's possible the switch collapsed and they can't tell the difference.
But Mr. S is clearly no newbie. If he says it's not jammed, it's a fairly
safe assumption that the tactile feedback of his play button is the same
as the rest of the buttons on the machine.

In servicing, it's a rule to never assume anything. It depends a lot on the
exact type of switch and how the outer 'user' button is implemented. Some of
the buttons have very little 'snap-action' feel to them, and the majority of
the return force on the user button comes from its plastic flexible hinge,
rather than from the switch itself. In those cases, it is perfectly possible
for the switch to collapse, but for the button not to feel much, if any,
different from normal or from any of the others. With some other types, the
travel of the switch plunger is so small on a correctly operating one, that
a collapsed one feels little different. Also, bear in mind that these
switches do not normally collapse spontaneously. Instead, they wear, until
one day, the last little bit of movement expires, and the switch goes short.
The switch will then feel absolutely no different today when it no longer
works, than it did yesterday when it did work ...

Yes, you are right that William is "no newbie", but by the same token, he is
not a 'current' engineer, and may not be able to feel the subtle differences
that we are talking here, without understanding the way his unit is put
together, and the failure mechanisms involved in these switches.

Arfa

"Arfa Daily" wrote in message ...

Yes, you are right that William is "no newbie", but by the same
token, he is not a 'current' engineer, and may not be able to feel
the subtle differences that we are talking here, without understanding
the way his unit is put together, and the failure mechanisms involved
in these switches.

Which you have explained very well.

PS: I am very capable of feeling subtle differences -- especially in a product
I have used many times.

As soon as I find the service manual (which I'll be looking
for this morning), I'll let you guys know. (I'm sure you're
waiting with bated breath.)

Found it, and have "released" the lid. Unfortunately, the bottom of the unit
gets in the way of it swinging back, so //that's// going to have to come off.

Nothing is ever simple. I just keep telling myself "It's kaput, so what
difference does it make?"

On Wednesday, December 3, 2014 10:14:05 AM UTC-5, William Sommerwerck wrote:
As soon as I find the service manual (which I'll be looking
for this morning), I'll let you guys know. (I'm sure you're
waiting with bated breath.)

Found it, and have "released" the lid. Unfortunately, the bottom of the unit
gets in the way of it swinging back, so //that's// going to have to come off.

Nothing is ever simple. I just keep telling myself "It's kaput, so what
difference does it make?"

Morbid curiosity most likely. If you've got time that would otherwise be wasted watching TV, then you'll probably enjoy solving the puzzle more.

"John-Del" wrote in message
...
On Wednesday, December 3, 2014 10:14:05 AM UTC-5, William Sommerwerck wrote:

Nothing is ever simple. I just keep telling myself "It's kaput,
so what difference does it make?"

Morbid curiosity most likely.

We like to think we're "smarter" than the equipment we're working on. In this
case, though... There's no question the Play button is shorted to ground even
when it's not pressed. But... the controls work through a resistor ladder, and
the readings I get for the resistors are backwards (eg, the 10K "base"
resistor is readable only when the Play button is pressed, though it should be
other other way around). This, of course, has nothing to do with the problem
(I think), but it drives me crazy.

"Just for luck", I pulled the cable from the main board and reinserted it. I
think I'll just put it back together and forget about it. (This problems isn't
going to have one of those "It works! It's a miracle!" endings.)

I have spares, and this model (D-FJ75TR) shows up on eBay occasionally at a
low price. So it's no big deal.


If you've got time that would otherwise be wasted watching TV,
then you'll probably enjoy solving the puzzle more.

I have a pile of books worth reading (among others, I'm working my way through
LIFE's "The Old West"), and a list as long as my arm of things to update or
repair. I'm trying to do one a day, but it's more like two a week. I just blew
out a classic Lux amp, so that's risen to the top of my list.

I did watch two Blu-ray movies yesterday, "Gojira" and "42". I was anxious to
see the latter, as an acquaintance was in it. TV watching is limited to when I
go to bed -- which, in this weather, is fairly early.