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Thread: PET 3032 garbage screen problem

  1. #91

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    Quote Originally Posted by Fran View Post
    I just remembered that I have a ZX-81 for parts with rams working. Is this ram valid for the pet?

    Attachment 56138
    The value of a VX81 is much more than a 2114.
    Dwight

  2. #92
    Join Date
    May 2011
    Location
    Outer Mongolia
    Posts
    1,638

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    I used 2149s in place of 2114s to replace the VRAM in a Dynamic-board PET, you should be able to sub them for 2114s if you find they're more available. (There was an electronics shop locally that had them in stock.) The 2114 supports a "low power" mode the 2149 doesn't, but I don't think the PET needs it. (In exchange the 2149 is faster.)

  3. #93

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    Hi
    Ram 2114 from China have arrived today, surprise, they are 2114-2 instead of 2114
    Original ram 450ns, China ram 200ns

    I have desoldered the ram and placed 2 sockets in its place

    20190923_222624.jpg 20190924_074124.jpg

    F7 ram 2114-2
    F8 ram 2114

    and voila!!!!

    20190924_204319.jpg

    Thanks guys

    Now the PET has one 450ns ram and one 200ns ram, can there be a problem?

    The next step is to solve a keyboard key failure, and the last step will be to fix the monitor, it does not turn on.

  4. #94

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    Quote Originally Posted by Fran View Post
    Hi

    F7 ram 2114-2
    F8 ram 2114

    and voila!!!!

    Now the PET has one 450ns ram and one 200ns ram, can there be a problem?
    This shouldn't hurt any thing. The 200ns might make a little more supply noise but shifted in time relative to the 450ns one so I see no issue.
    What are the keyboard issues and how do you get a display if it won't turn on?
    Dwight

  5. #95

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    One of the keys does not work, pressing it should not make contact
    Dwight as you can see in this image with a composite video adapter

    20190924_213936.jpg

  6. #96
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,190

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    Nice job Fran.

    Probably worth running a memory test on the machine all the same if you haven't done already.

    Where did you get your composite video adapter from by the way. I see a few where you can download the design and get your own PCB made, but (to be honest) I would rather just buy one for my own PET. I have enough projects to do without another one...

    Dave

  7. #97
    Join Date
    Feb 2009
    Location
    Southern California, USA
    Posts
    2,706

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    Quote Originally Posted by Fran View Post

    F7 ram 2114-2
    F8 ram 2114

    and voila!!!!
    So the only problem was the F7 video RAM? So Dwight was correct that the several problems seen on the screen that looked like addressing issues were all internal to the RAM chip containing the upper four bits. Wow, good call!
    -Dave

  8. #98

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    Quote Originally Posted by dave_m View Post
    So the only problem was the F7 video RAM? So Dwight was correct that the several problems seen on the screen that looked like addressing issues were all internal to the RAM chip containing the upper four bits. Wow, good call!
    -Dave
    Kudos to Dwight!

    Frank

  9. #99

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    Quote Originally Posted by daver2 View Post
    Nice job Fran.

    Where did you get your composite video adapter from by the way. I see a few where you can download the design and get your own PCB made, but (to be honest) I would rather just buy one for my own PET. I have enough projects to do without another one...

    Dave
    Hi Dave

    This is the diagram to make your own composite video adapter

    20190925_220956.jpg

    http://www.dasarodesigns.com/product...t-video-mixer/

    Following the diagram I made my own composite video adapters:

    First

    20181201_211438.jpg

    Second

    20181207_172909.jpg

    and finally I bought it on the Dave Curran website http://www.tynemouthsoftware.co.uk

    20190925_224334.jpg 20190925_224343.jpg

    Send an email to Dave info@tynemouthsoftware.co.uk

    This is the email I exchanged with Dave:

    Q:Where can I buy your commodore pet composite video??
    A:You can order direct from me. What version do you want, I have one which connects internally, or one which plugs into the user port at the back of the machine. Also which model PET is it for, later ones require a replacement editor ROM with custom timings to drive composite video.

  10. #100
    Join Date
    Jun 2012
    Location
    UK - Worcester
    Posts
    3,190

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    Thanks.

    I looked on the site but couldn't see them advertised. I will send him an e-mail.

    Dave

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