On 2020-10-06 15:50, George N. White III wrote:
On Tue, 6 Oct 2020 at 14:02, Roger Heflin <rogerheflin@xxxxxxxxx
<mailto:rogerheflin@xxxxxxxxx>> wrote:
And on top of what George says, it might be best to make sure the
printer is on the same breaker/120Leg as the computer.
If the computer is on a UPS and the printer is not then if possible
make sure the printer is plugged into the same outlet as the UPS.
but only if outlet can handle the total (printer + UPS) load. I've seen
cases where a printer plus UPS worked fine until shortly after a power
outage when the combined normal UPS load + UPS charging load +
printer exceeded the circuit capacity and tripped a breaker (on the
panel in a locked wiring closet -- Murphy's Law loves to double down).
Also note that I don't know which power system you are on, I am
familiar with the US hot/neutral/ground 3-prong plug which is supposed
to just work for this, but there are a number of mis-wirings (of both
the outlet and the device) that are common enough to not be unlikely.
In the US there are simple <$10 devices (most hardware stores) that
plug into outlets and light up and tell you if the outlets are wired
correctly.
Many UPS's will also detect wiring problems and refuse to run. I've
seen that on 2 occasions where a ground connection in the
building wiring failed in service. The extra wire protects against
induced currents (lightning, nearby high-voltage distribution lines).
Weird ground issues produce really odd behavior. If everything
involved is using a proper ground outlet and the outlets are properly
ground and all of the devices are properly wired then you should not
have a weird ground issue, which is what this sounds like, and was why
Geroge mentions running a wire to make sure the ground is right. If
you have a multimeter you could check resistance between a metal part
on the printer and a metal part on the computer without the printer
cable attached, if everything is right the resistance should be almost
0, if the resistance is not almost zero then something really is wired
wrong. If the resistance is non-zero then there is a decent chance
that the ground on one device vs the other could be a few volts
difference (you can also check that with the meter, but it may or may
not be different enough at the moment), with a small amount it will
think there is a signal when there is not, and with a larger
difference any electronics (the parallel port card) may burn because
there is current flowing were it is not designed to flow.
On Tue, Oct 6, 2020 at 10:46 AM George N. White III
<gnwiii@xxxxxxxxx <mailto:gnwiii@xxxxxxxxx>> wrote:
>
> On Tue, 6 Oct 2020 at 03:03, ToddAndMargo via users
<users@xxxxxxxxxxxxxxxxxxxxxxx
<mailto:users@xxxxxxxxxxxxxxxxxxxxxxx>> wrote:
>>
>> On 2020-10-05 19:20, Tim via users wrote:
>> > On Mon, 2020-10-05 at 17:15 -0700, ToddAndMargo via users wrote:
>> >> I think I am going to replace the parallel port card
>> >> "just because"
>> >
>> > If your parallel port is on a card, then simply removing the
card ought
>> > to show whether *it* is the problem.
>> >
>> > Peripherals are a prime area of hardware failure. When you
have two
>> > mains powered devices hooked together, and one or more of them
isn't
>> > earthed, or you connect them together while the equipment is
on, it's
>> > very easy to zap components. They mayn't die instantly, but
can be
>> > weakened.
>> >
>> > Peripherals connected between buildings, or even between
rooms, also
>> > suffer the same kind of risk.
>>
>> It decides when to poop out. It is not all
>> that easy to reproduce.
>>
>> Basically, it poops out when I need it the most.
>
>
> Run a wire (at least 18 gauge) from the chassis of the PC to the
chassis of the printer.
> This should greatly reduce the chances for the parallel port
getting zapped. You might
> also think about using a more modern interface, with USB to
parallel converter or adding
> a network interface to the printer and disposing of the parallel
port.
>
>
--
George N. White III
Printer is on the same UPS, but surge only side. This
is a new symptom. It has worked this way for years.
It is an Okidata B4350 and I love the thing. It just
keeps going and going and going ...
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