The replacement arrived this morning and it's now working OK. In a much
larger box with some ventilation.
The on load voltage is 5.4v - but it worked OK with the temporary 5v one.
Wonder why it's such an odd value?

--
*WHOSE CRUEL IDEA WAS IT FOR THE WORD 'LISP' TO HAVE 'S' IN IT?

Dave Plowman London SW
To e-mail, change noise into sound.

En el artículo , Dave Plowman (News)
escribió:

Wonder why it's such an odd value?

It's faulty, there isn't enough load on it to regulate properly, or it's
an unregulated one.

The power probably goes direct to the ICs inside the KVM (in other
words, there's no supplementary power supply on the KVM board.)

It should be 5v +/- 5%, so 4.75 min to 5.25v max.

I wouldn't be comfortable using it on equipment specified for 5.0v.

--
:: je suis Charlie :: yo soy Charlie :: ik ben Charlie ::

In article ,
Mike Tomlinson wrote:
En el artículo , Dave Plowman (News)
escribió:

Wonder why it's such an odd value?

It's faulty, there isn't enough load on it to regulate properly, or it's
an unregulated one.

The power probably goes direct to the ICs inside the KVM (in other
words, there's no supplementary power supply on the KVM board.)

It should be 5v +/- 5%, so 4.75 min to 5.25v max.

I wouldn't be comfortable using it on equipment specified for 5.0v.

But it says 5.4v on the original PS case. ;-)

When faulty it read just over 4v under load. Must admit I didn't measure
the bench PS.

--
*HOW DO THEY GET DEER TO CROSS THE ROAD ONLY AT THOSE YELLOW ROAD SIGNS?

Dave Plowman London SW
To e-mail, change noise into sound.

On 11/02/2015 01:04, Mike Tomlinson wrote:
En el artículo , Dave Plowman (News)
escribió:

Wonder why it's such an odd value?

It's faulty, there isn't enough load on it to regulate properly, or it's
an unregulated one.

The power probably goes direct to the ICs inside the KVM (in other
words, there's no supplementary power supply on the KVM board.)

It should be 5v +/- 5%, so 4.75 min to 5.25v max.

I wouldn't be comfortable using it on equipment specified for 5.0v.


Not all logic is 5V +/- 5%.
CMOS worked over a wide range and could even be biased to work as amps,
etc.
A usb device should be protected against odd voltages.
TTL was +/- 10% AIRI.

On Wed, 11 Feb 2015 09:37:53 +0000, "Dennis@home"
wrote:

On 11/02/2015 01:04, Mike Tomlinson wrote:
En el artículo , Dave Plowman (News)
escribió:

Wonder why it's such an odd value?

It's faulty, there isn't enough load on it to regulate properly, or it's
an unregulated one.

The power probably goes direct to the ICs inside the KVM (in other
words, there's no supplementary power supply on the KVM board.)

It should be 5v +/- 5%, so 4.75 min to 5.25v max.

I wouldn't be comfortable using it on equipment specified for 5.0v.


Not all logic is 5V +/- 5%.
CMOS worked over a wide range and could even be biased to work as amps,
etc.
A usb device should be protected against odd voltages.
TTL was +/- 10% AIRI.

This last is true, +/- 10% was the standard operating tolerance for
TTL. The +/- 5% for PSU rails was the means used to guarantee
compatability between power rail voltages and TTL chip requirements in
the face of inevitable volt drops between supply and devices (cable
and circuit trace volt drops).

As you mentioned, standard cmos had a much wider operating voltage
tolerance (3 to 15 volt, afaicr) depending on how fast you wished to
operate the silicon. The cmos versions of the TTL family otoh, were
specced for the same tighter 5v +/- 10% of standard TTL (mainly to
meet speed specifications and retain compatability with existing TTL
devices).
--
J B Good