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  • Televideo PT-100 - Video just went out

    From Gandalf@21:4/153 to All on Tuesday, January 07, 2020 23:43:40
    A while back, I dusted off my Televideo PT-100 dumb terminal and have been really enjoying the monochrome phosphorus glow while BBSing. This evening
    that came to a halt when, while playing LORD, the video suddenly flickered
    and went out. Doh!

    Now, I am back on my laptop, reaching out to see if someone may be able to offer suggestions on how I can fix it. I am unsure if it is a bad cap or
    the flyback transformer. It has been thirty years since I worked on CRT's.
    I
    I have a DMM, O-Scope, and time. I do not have a schematic and can't find
    one online.

    Thanks in advance for reading about my dumb terminal blues (insert Muddy
    Waters - I'm A Man intro riff here) and for any suggestions offered.

    Gandalf The Blue

    --- Mystic BBS v1.12 A43 2019/03/02 (Linux/64)
    * Origin: ARDA-BBS (21:4/153)
  • From poindexter FORTRAN@21:4/122 to Gandalf on Wednesday, January 08, 2020 06:54:00
    Gandalf wrote to All <=-

    Now, I am back on my laptop, reaching out to see if someone may be able
    to offer suggestions on how I can fix it. I am unsure if it is a bad
    cap or the flyback transformer.

    As someone who was scared shitless of opening up a CRT and getting shocked,
    I always assumed that the flyback transformer would make noise before going bad, where as caps would just pop and die?




    ... Listen in total darkness, very quietly
    --- MultiMail/XT v0.52
    * Origin: http://realitycheckbbs.org (21:4/122)
  • From Gandalf@21:4/153 to poindexter FORTRAN on Wednesday, January 08, 2020 15:11:58
    As someone who was scared shitless of opening up a CRT and getting shocked, I always assumed that the flyback transformer would make noise before going bad, where as caps would just pop and die?

    Great point! I will start checking the caps.

    --- Mystic BBS v1.12 A43 2019/03/02 (Linux/64)
    * Origin: ARDA-BBS (21:4/153)
  • From Spectre@21:3/101 to Gandalf on Thursday, January 09, 2020 12:40:00
    As someone who was scared shitless of opening up a CRT and getting shocked, I always assumed that the flyback transformer would make noise before going bad, where as caps would just pop and die?

    Great point! I will start checking the caps.

    Caps are a great place to start, I don't know about this particular terminal, but worth checking the solder joints around the EHT/flyback.. some tend to break them eventually. You could also lift the cover and see if the neck of the tube is still glowing in the dark, would show the tube is still likely
    ok, and its missing drive.

    Phase one would have to be check the power supply voltages just in case...

    Spec


    *** THE READER V4.50 [freeware]

    --- SuperBBS v1.17-3 (Eval)
    * Origin: Scrawled in haste at The Lower Planes (21:3/101)
  • From Nigel Reed@21:2/101 to Gandalf on Wednesday, January 08, 2020 21:19:38
    Gandalf wrote:
    A while back, I dusted off my Televideo PT-100 dumb terminal and have been really enjoying the monochrome phosphorus glow while BBSing. This evening that came to a halt when, while playing LORD, the video suddenly flickered and went out. Doh!

    Now, I am back on my laptop, reaching out to see if someone may be able to offer suggestions on how I can fix it. I am unsure if it is a bad cap or the flyback transformer. It has been thirty years since I worked on CRT's. I
    I have a DMM, O-Scope, and time. I do not have a schematic and can't find one online.

    Thanks in advance for reading about my dumb terminal blues (insert Muddy Waters - I'm A Man intro riff here) and for any suggestions offered.


    Not realted to your problem, but I just found an old Computer World (July 14 1980) ad for a PT100. "If you're tired of waiting for a DEC* VT-100, Go with ITI's PT-100 VIDEO DISPLAY TERMINAL by Plessey" Only $2385

    Dang! that's expensive!
    --- SBBSecho 3.10-Linux
    * Origin: End Of The Line BBS - endofthelinebbs.com (21:2/101)
  • From Gandalf@21:4/153 to Spectre on Thursday, January 09, 2020 13:32:06
    Caps are a great place to start, I don't know about this particular terminal, but worth checking the solder joints around the EHT/flyback.. some tend to break them eventually. You could also lift the cover and
    see if the neck of the tube is still glowing in the dark, would show the tube is still likely ok, and its missing drive.

    Thank you Spec - will do!

    --- Mystic BBS v1.12 A43 2019/03/02 (Linux/64)
    * Origin: ARDA-BBS (21:4/153)
  • From Gandalf@21:4/153 to Nigel Reed on Thursday, January 09, 2020 13:33:39
    Not realted to your problem, but I just found an old Computer World
    (July 14 1980) ad for a PT100. "If you're tired of waiting for a DEC* VT-100, Go with ITI's PT-100 VIDEO DISPLAY TERMINAL by Plessey" Only
    $2385

    Dang! that's expensive!

    Wow! I will have to check that advert out!

    --- Mystic BBS v1.12 A43 2019/03/02 (Linux/64)
    * Origin: ARDA-BBS (21:4/153)