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Thread: Build your own PDP 8I, Part 4..

  1. #171
    Join Date
    Oct 2011
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    Bedford, NH, USA
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    Quote Originally Posted by Chuck(G) View Post
    If it all works out, that's a great price. However, you need to add a manual unwrap tool to your arsenal, if you don't have one. Mistakes will be made.

    OK, Vector, Radio Shack, etc. are all pretty much the same. I like the double-ended OK one as it serves as both a wrap and an unwrap tool.
    Yes, indeed! I already have a multi-function (wrap, unwrap, & strip) tool made by Electronic Express. Not one of the companies you mentioned, but at least I have something to use when I need it. I originally purchased this to deal with all the wire-wrapped option selections on my DEC Q-Bus boards.

    Thanks!

    smp

  2. #172
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    >>> Dave, are you incrementally updating the construction/assembly manual on your Google Drive? Or should I wait a bit to get the benefit of your experience?

    I will update what is on my google drive when I have installed the capacitors, debug LEDs and IC sockets if that is OK with you all. It gives me something to aim at as I don't want to fall too far behind everyone else's construction if I am bogged down writing documentation (if you get my drift).

    If (for some reason) I have to drop the project due to work; I will be quite happy to update my google drive with where I am to save holding other people up.

    You should have a private mail regarding the KiCAD query.

    Dave

  3. #173
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    If it's this one,
    I suspect it's just a re-badging of the OK one.

  4. #174
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    >>> Dave, are you incrementally updating the construction/assembly manual on your Google Drive? Or should I wait a bit to get the benefit of your experience?

    I have updated the construction manual on my google drive. I haven't installed any components in it yet... I am off to take some more photographs in a second or two of the capacitors. It is getting too late now to do any soldering though - so it will have to wait until tomorrow now. I would, in the meantime, value some feedback as to how I am structuring the manual and the content before I go too mad!

    Regards,

    Dave

  5. #175
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    Quote Originally Posted by Chuck(G) View Post
    If it's this one,
    I suspect it's just a re-badging of the OK one.
    Yes, that's it. Thanks for the info!

    smp

  6. #176
    Join Date
    Mar 2004
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    Wilmette, IL (north of Chicago)
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    I've installed and soldered my sockets and decoupling caps. Since the netlists seem to be in temporary limbo, I'll wait for daver2 to catch up.

    The manual (at least through page 11) seems quite comprehensive and helpful.

    I would only make two recommendations at this point -

    1) Any one wanting to verify board integrity and/or check for shorts should have a multimeter with a "beeper" (or even just wire up a stand-alone continuity tester with some sort of audio output). It's hard enough keeping track of probe placement on a board this size without having to continually be checking back to read the meter display.

    2) The first paragraph on page 11, testing for continuity across the RAM array, deserves its own check box.

    I've chosen to solder in my sockets; minimally to connect VCC and GND and at all four corners on the .6" wide 40 pin sockets. I also soldered all the RAM connections. Given the pre-wired connections on the logic board, it seems that only pins 8 and 12 for each of the RAM sockets need to be available for additional wired connections; if this is the case, clipping the other pins closer to the board would make soldering and inspecting the array connections much easier.

    Once all sockets were installed, I did VCC and GND short and continuity tests from the actual sockets to verify the integrity of my soldering work. I expect this will be covered in the Socket Installation yet to be written. :>)

    Thanks again, Dave, for the tremendous amount of work you're putting into this project!

  7. #177
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    >>> Thanks again, Dave, for the tremendous amount of work you're putting into this project!

    Thanks for the thanks !

    1) I will add a section on "tools required". I thought about this - and then promptly forgot about it!
    2) I will add a checkbox for the RAM array test.

    Yep, will add a corresponding check after soldering for continuity and inadvertant short circuits.

    Dave

  8. #178
    Join Date
    Jul 2009
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    Boulder , Colorado USA
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    Hi All;

    Dave, I plan on going a slightly different route, I first will make it using the 7489's for Ram Memory, and then I will switch to 2102's, since I don't have the Rams that You have or are using on Your Board..
    And, somewhere, I have seen a schematic for using 2102's, and that should help me make the final unit work for me..

    I have wired in the 6 test Led's, I just need to test them.. My Power supply has banana jacks, but, there is no such place on the board for attaching power.. So, I'LL have to figure something out.. Is there something on the Front Panel for attaching Power and Ground ??

    I have a Battery Powered Wire-wrap Gun, ( I got it Years ago) but, it will not work with the two "C" Batteries, that are supposed to make it work.. Not enough oomph.. I need to modify it to work with a Power Supply and see what voltage will make it run..

    THANK YOU Marty

  9. #179
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    It's your board - you do with it what you want... That is the great idea of this thing!

    There are copper pads for attaching +5V, 0V/GND, +12V and -5V to the board. They are located on the underside/solder/wrapping side of the PCB by the P2 connector. I will put similar pads on the front panel. These pads are like the original.

    Keep an eye on my google drive for updates to the construction manual. I have just updated it as a result of a PM from Jack to add a preliminary BoM for the front panel (since I am currently working on it). Been talking to a company about producing an acrylic panel to cover the LEDs and switches to make it look pretty (a-la PDP-8/L like)...

    Dave

  10. #180
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    Jul 2009
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    Hi All;

    Dave, Thank You for the Reply..

    "" There are copper pads for attaching +5V, 0V/GND, +12V and -5V to the board. ""

    Yes, I saw them, I wasn't sure if I should solder any wire to them..

    Has the Schematic changed from Your Original Posting, since I have that already Printed up ??

    Will the Front Panel be Released anytime soon ??

    THANK YOU, for all of Your Tremendous Work on this Project ..

    THANK YOU Marty

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