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Thread: Need some help getting a DEC VT100 working

  1. #1
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    Default Need some help getting a DEC VT100 working

    Hi lucky lucky i got a vt100 in a flea market, cost me like 20 usd dollars i was unable to say no to this beauty !.
    And was shrink wrapped, looking great getting tanned in the scorching sun of summer 38C.
    Took this baby home removed the shrink wrap was in great external condition, the keyboard rubber feet was melted and stuck to the top of the terminal i have to cut them using a knife.

    names that start with a and end in y

    Now the problem, first the fuse was blown and the terminal was set to 110v this is a 220v country, change the setting replace the fuse and get it powering up.


    Disassembled it, was quite easy. But but but but like Jeff Goldblum could say theres no display in the terminal. Hooked an external tv using the composite output and can see some corrupted text fonts on the TV. No video on the internal display.

    The keyboard light online turn on but no beeps or blips from the speaker.

    The cathode in the picture tube light up and got a bright line and dot when powering it up.

    So i believe i have two problems one related to the analog board on the monitor itslef (no picture) and another related to the digital side of things (garbled up charters on the external composite output).

    Using the multi meter checked the digital board i have a steady +12 and +5 lines on the power rails.

    Maybe someone can help me in getting this to work i'm quite lost!.

  2. #2

    Default

    When there is no beep at startup my experience is that the low ROM is bad. If you have the AVO this ROM can be replaced with a ordinary 2716. Another option is to use a MCM68766 to replace all the ROMs on the main board. Now, MCM68766 is not that common so one may need to make an adapter. I did this based on a design on OSHpark. Here is a link to my page: http://www.datormuseum.se/peripherals/terminals/vt100

    Since you get something on the screen the HV might work. But I once had a flyback fail in these.

    Good luck!

  3. #3
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    Thanks for the information and your webpage will help me a lot .
    Do you know the video input on the back of the terminal if you plug a composite signal it should display on the internal monitor ?.

  4. #4
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    Default

    got the screen fixed


    Now the hard part i have checked the links on how to replace the roms using the flash chip and don't look very easy.

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