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Phantom Printer?

08/03/2020 11:01 PM

Trying to figure this out.... Listening to any comment

I work with laboratory equipment connected to this Okidata printer. Funny thing is after the equipment sending data to the printer is powered off overnight. We can come in the next morning (not every morning) and find several pages on the printer with these printouts of a single character.

Communicating with other sites with the same system/printer, they have seen the same thing.

Is the printer trying to tell me something??

Or is this an alien infestation?

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#1

Re: Phantom Printer?

08/03/2020 11:47 PM

Probably just checking startup parameters and updating information...but could be several single or combined glitches causing it to print the results...

https://smallbusiness.chron.com/printer-printing-symbols-57406.html

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#2

Re: Phantom Printer?

08/04/2020 12:31 PM

According to OKI, it could be a bad serial cable...

https://okiprinting-en-us.custhelp.com/app/answers/detail/a_id/1868/~/garbage-printing-occurs-when-printing-from-the-serial-port

If the connected equipment is powered off but the printer is powered on, my guess is that the powered down connected equipment looks like an open circuit and electrical noise in the environment is being picked up by the cable and interpreted by the printer as valid input.

To minimize noise, a serial cable should be shielded (shield grounded at one end), with a length as short as possible, and not bundled closely with other cables which might couple in noise.

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#3

Re: Phantom Printer?

08/05/2020 2:16 AM

I installed a 4 foot led fixture in my shop, I've noticed that sometimes the led's are dark, while other times their lit up like st elnmos fire,,,

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#4

Re: Phantom Printer?

08/05/2020 7:25 PM

Try unplugging the serial cable at night and see if the issue goes away.

In addition to using a shielded serial cable you could:

1) Review how the serial cable is routed. Does it pass by anything that is switching large values of current?

2) This is somewhat unconventional but you could try VERY WEAK pull-up or pull-down resistors. This is a little tricky because the RS-232 levels are probably between +3 and +12 for one state and between -3 and -12 for the other state. Key problem, ground is not a valid state. Some devices provide in the connector the positive and negative voltages but most do not.

It has been many years since I have used traditional serial data. I have forgotten a lot. You probably have at least one printer output pin (handshaking pin) that is driven at a constant state while other devices are turned off at night. You could use some connectors and an oscilloscope to look at the signal lines. Then experiment with resistors (possibly starting with 47K) and see if you feel comfortable that you can pull the inputs while the computer is off but not corrupt the signals when the computer is on.

A weak pull to ground might help stabilize things but as stated before, ground is in between states and you normally do not want your signal lines to hang out there.

Power is never clean and grounds like to bounce. With an open circuit input all sorts of unexpected things could happen. You could even walk in one day and see the winning lottery numbers on your printer.

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#7
In reply to #4

Re: Phantom Printer?

08/07/2020 8:18 AM

Good answer.

I agree that looking for a way to bias the signal (Rx at printer) should work.

A couple of these RS232 to 485 converters would improve all aspects of noise immunity, and, enable much longer cables. Might need to do a little gender bending at one or other end.

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#5

Re: Phantom Printer?

08/05/2020 8:22 PM

Thanks all,

I will look for a better, shielded cable.

This was supplied by manufacturer of the analyzer.

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#6

Re: Phantom Printer?

08/07/2020 1:38 AM

Haha, this is fun. Thank you for sharing!

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#8

Re: Phantom Printer?

08/09/2020 12:05 AM

If the electricity shield or whatever is faulty, why specific figures? Why not a jumble of earlier print option ?

Passing them off as shield related etc, is veering off the issue especially with a power turned off, printer .

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#10
In reply to #8

Re: Phantom Printer?

08/09/2020 4:44 AM

From his post it seems that only the input equipment is turned off, the printer stays on. It is not a printer without power.

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#9

Re: Phantom Printer?

08/09/2020 4:14 AM

Yep, pretty sure its aliens or ghosts.

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#11

Re: Phantom Printer?

08/09/2020 8:07 AM

Save all of the printouts!

You may be receiving messages from the 5th dimension from a captured political prisoner.

The DIY transmitter can only send a few bits at the time,during a short time frame.

When you have accumulated enough of these images,convert them to ASCII ,then to binary,subtract one,then convert to octal,subtract 20, and input them into a TI 994A and use the voice synthesizer to hear what is being said.

The message may be only in Click Language,so you may need an interpreter.

https://www.youtube.com/watch?v=vhgb60Qsjrs

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#12

Re: Phantom Printer?

08/09/2020 8:15 AM

Comment #11 seems to be of the same genre - phantom !

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#13

Re: Phantom Printer?

08/10/2020 12:33 PM

You could read the book "Lost Boys" by Orson Scott Card and then check your basement or crawlspace for disturbed soil.

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