Keyboard Cable With PS-2 Connector

[ColTom2]

Hi:

I posted this subject last month, but now have additional questions.

" I have a Sony VGC-RA716G desktop computer running XP MCE(2006) SP3 with
PS-2 cable for keyboard. The PS-2 connector on the end of the cable got bent
and is now defective."

I acquired an old Gateway keyboard with six pin male PS-2 connector. I cut
it off about a foot from the end and took an ohm meter where I could
determine the wiring color to each connector pin. However, on the Sony
connector I was unable to do this.

So I opened the keyboards and recorded the wire colors to the female end
of connector to the board. The female connector to each keyboard has 4 wires
attached and also ground wire. Naturally the wire coding is different
applicable each keyboard.
However, if I matched the wires corresponding to their 4 locations from L to
R on the female connector and soldered them together would this be correct?
This was the only rationale that I could come up with that would possibly
work.

Also say I did have the wires matched together wrong and plugged it into
my desktop would it blow the female PS-2 keyboard port?

Thanks,

Col Tom2

 

[Paul]

Hi:

I posted this subject last month, but now have additional questions.

" I have a Sony VGC-RA716G desktop computer running XP MCE(2006) SP3 with
PS-2 cable for keyboard. The PS-2 connector on the end of the cable got bent
and is now defective."

I acquired an old Gateway keyboard with six pin male PS-2 connector. I cut
it off about a foot from the end and took an ohm meter where I could
determine the wiring color to each connector pin. However, on the Sony
connector I was unable to do this.

So I opened the keyboards and recorded the wire colors to the female end
of connector to the board. The female connector to each keyboard has 4 wires
attached and also ground wire. Naturally the wire coding is different
applicable each keyboard.
However, if I matched the wires corresponding to their 4 locations from L to
R on the female connector and soldered them together would this be correct?
This was the only rationale that I could come up with that would possibly
work.

Also say I did have the wires matched together wrong and plugged it into
my desktop would it blow the female PS-2 keyboard port?

Thanks,

Col Tom2

The physical location of the pads on the PCB, doesn't have to match. It could be
"GND clock data POWER" on one keyboard, and "POWER data clock GND" on the
other, to name just one of many possibilities. The designer doesn't need
to worry about interchanging components here.

I would have hoped the cables would share something like "red" for +5V
and "black" for GND. But I know better than that. Nobody bothers
with convention, when they're not required to. That is what I'd use
in a cable like that, while Clock and Data would be a more arbitrary
choice.

That is why, buzzing the Sony cable, to get pin position versus color,
is necessary. You want a reasonable assurance you know what is going
on, before reaching for the soldering iron.

To do it now, you're going to need some info about the schematic
of the Sony keyboard. You'd be looking for evidence of fat tracks
or connection to +5V plane or GND plane, to help you figure out which
is which. You must get +5V and GND correct, to prevent damage to the
keyboard. If Clock and Data are reversed, chances are it'll survive
that, as I believe they're open collector. Just unsolder those signals
and swap them, if it doesn't work. But any other kinds of screwups,
such as reversing +5V and GND, or connecting power to one of the
data pins, would increase the chances of seeing "magic smoke".

So if you cannot buzz the Sony cable, to determine the pinout, you're
going to need inference from the keyboard design itself, as to which
color does what. A much tougher job.

The thing is, they're "Sony", and historically, Sony doesn't do
things the same as everyone else. So I see no reason for
one of their engineers, to put the pads on the keyboard PCB,
in the same order as some cheap Chinese keyboard.

Paul

 

[ColTom2]

Hi Paul:

It sounds like he best thing that I can do is trash the Sony keyboard, as
I have another and this one if repaired would only be a back up.

I certainly would not want to mess the PS-2 keyboard port up in my desktop
just trying to get a useless keyboard restored.

I really appreciate your extensive info provided in your reply.

ColTom2

Hi:

I posted this subject last month, but now have additional questions.

" I have a Sony VGC-RA716G desktop computer running XP MCE(2006) SP3 with
PS-2 cable for keyboard. The PS-2 connector on the end of the cable got
bent
and is now defective."

I acquired an old Gateway keyboard with six pin male PS-2 connector. I
cut
it off about a foot from the end and took an ohm meter where I could
determine the wiring color to each connector pin. However, on the Sony
connector I was unable to do this.

So I opened the keyboards and recorded the wire colors to the female end
of connector to the board. The female connector to each keyboard has 4
wires
attached and also ground wire. Naturally the wire coding is different
applicable each keyboard.
However, if I matched the wires corresponding to their 4 locations from L
to
R on the female connector and soldered them together would this be
correct?
This was the only rationale that I could come up with that would possibly
work.

Also say I did have the wires matched together wrong and plugged it into
my desktop would it blow the female PS-2 keyboard port?

Thanks,

Col Tom2

The physical location of the pads on the PCB, doesn't have to match. It
could be
"GND clock data POWER" on one keyboard, and "POWER data clock GND" on the
other, to name just one of many possibilities. The designer doesn't need
to worry about interchanging components here.

I would have hoped the cables would share something like "red" for +5V
and "black" for GND. But I know better than that. Nobody bothers
with convention, when they're not required to. That is what I'd use
in a cable like that, while Clock and Data would be a more arbitrary
choice.

That is why, buzzing the Sony cable, to get pin position versus color,
is necessary. You want a reasonable assurance you know what is going
on, before reaching for the soldering iron.

To do it now, you're going to need some info about the schematic
of the Sony keyboard. You'd be looking for evidence of fat tracks
or connection to +5V plane or GND plane, to help you figure out which
is which. You must get +5V and GND correct, to prevent damage to the
keyboard. If Clock and Data are reversed, chances are it'll survive
that, as I believe they're open collector. Just unsolder those signals
and swap them, if it doesn't work. But any other kinds of screwups,
such as reversing +5V and GND, or connecting power to one of the
data pins, would increase the chances of seeing "magic smoke".

So if you cannot buzz the Sony cable, to determine the pinout, you're
going to need inference from the keyboard design itself, as to which
color does what. A much tougher job.

The thing is, they're "Sony", and historically, Sony doesn't do
things the same as everyone else. So I see no reason for
one of their engineers, to put the pads on the keyboard PCB,
in the same order as some cheap Chinese keyboard.

Paul