On Tue, 2020-10-06 at 12:46 -0300, George N. White III wrote: > 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. That kind of thing can really help. I'm more into AV production and broadcasting, where solid grounding between equipment chassis is really well understood (by the right people), and we're used to having to deal with interconnecting multiple rooms and buildings. In one theatre, we found 4 volts (with quite a bit of current) between the earthing pins just two rooms apart. The building would have been three-phase, with long distances between the distribution boards and points, and the phases spread around everywhere. Not to mention the heavy currents induced by theatre lighting circuits. Earthed equipment (three-pin plugs) *should* take care of this for you (providing a common ground between equipment), but some types of plugs and sockets have all too easily damaged earthing connections, lots of things aren't earthed these days, and it's really only grounding the chassis (signal grounding usually shouldn't connect directly to mains earth). You mightn't even be aware of a non-working earth, because the equipment still appears to work fine without it. > 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. I wonder how much more robust USB is than parallel? The physical connections certainly aren't. USB sockets can be quite wobbly. I had to bend the tangs on a brand new USB hub to make the sockets grip the plugs, because the mouse kept disconnecting if someone breathed in the same room. And I'm sure some manufacturers would skimp on spike protection. I know that many network ports are not galvanically isolated (neither with optical coupling in a chip, nor using a signal transformer, and with sufficient voltage ratings). I had to replace the switch between two buildings quite often because of that. We've come across quite a few dead firewire connections thanks to sparking, too. They're meant to be hotpluggable, but when you connect one thing to another, with one or both having floating output switchmode power supplies, you can easily put a hundred volts or more into the connection. Sometimes you have not choice but to hotplug, too; it's the only way to get the devices to acknowledge a connection, turning the power on and off on already connected devices doesn't always work. -- uname -rsvp Linux 3.10.0-1127.19.1.el7.x86_64 #1 SMP Tue Aug 25 17:23:54 UTC 2020 x86_64 Boilerplate: All unexpected mail to my mailbox is automatically deleted. I will only get to see the messages that are posted to the mailing list. _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx
