Image Map Image Map
Page 1 of 3 123 LastLast
Results 1 to 10 of 27

Thread: IBM 5155 Portable Project: Looking for ideas and direction

  1. #1

    Default IBM 5155 Portable Project: Looking for ideas and direction

    So a little over a year ago now I picked up an IBM Portable 5155 that I found on the side of the road of all places. Anyways, to keep a long story short, virtually everything aside from the case, power supply (though that went out in a blazing glory when I tried to test it) and CRT was consumed by the onslaught of battery acid brought on from two expansion cards and their barrel batteries. Seriously, the board and expansion cards were toast as it just creeped along most of the traces it could get to and, making matters worse, the floppy drives had been pulled and the springs and switches in the keyboard were utterly ruined by rust.

    So with that said, after a lot of hard cleaning and partial re-assembling, sourcing a replacement power supply (still need a keyboard and CGA card) I'm now at the point where I'm considering different paths to take on this restoration, seeing as how I currently have a blank canvas, so to speak. The first is pretty straight forward; restore it back to it's original state. I'm sure this is the preferred method of a lot of you here, but seeing as I already have a PC, XT and AT, I kind of what to do something different and more creative here, which brings me to my other two concepts...

    1) Track down the original system board, a MACH 20 card, and two 1.2Mb floppy disk drives (or one disk drive and a hard drive) and make this machine an example of what it could have been later in it's life after being upgraded by a tech-savvy owner. This is my preferred method, though MACH 20s are hard to come by, especially with their additional memory and disk controller add-ons.

    2) Track down the system board from an XT-286 (or alternatively the later revision system board from an AT, both should still fit), the drive controller from an AT, a 1.2Mb disk drive and a 5.25" hard drive and skip the whole "tracking down a", and "paying out the nose for a MACH 20" thing.

    Anyways, what do you all think would be the best route or alternatively, what other route would you take with this project were it yours?

  2. #2
    Join Date
    Jan 2007
    Location
    Pacific Northwest, USA
    Posts
    31,775
    Blog Entries
    20

    Default

    Why not retrofit it with a modern nATX board, power supply and LCD monitor? You should have more than enough room to do it.

  3. #3

    Default

    Quote Originally Posted by Chuck(G) View Post
    Why not retrofit it with a modern nATX board, power supply and LCD monitor? You should have more than enough room to do it.
    Ehhhhh... That's not really my thing personally, though it is an interesting idea.

  4. #4
    Join Date
    Feb 2012
    Location
    New Zealand
    Posts
    2,622
    Blog Entries
    2

    Default

    I like option 1, but that's my personal taste.
    Also with motherboards, going with an AT style could leave you in a pickle when it comes to the keyboard.

    One mod I'd love to see on one of these would be a colour CRT. Chosen to fit the chassis and hooked to the composite colour output on the CGA card.
    WTB: IBM RT Parts and Accessories, and AOS.
    Twitter / Discord / YouTube / Twitch

  5. #5

    Default

    I love my 5155, but I really wish they had made the internal monitor a true-CGA. Composite creates weird artifacts on certain colors.

    But, once you get past that, it’s a fabulous machine. Also, setting DOS to black & white with the “mode bw80” command helps with the screen. The amber display is very nice.

    I just recently put a HardCard 20 in mine to make it more useful.
    Compaq - “It simply works better”

  6. #6

    Default

    [QUOTE=compaqportableplus;579194]I love my 5155, but I really wish they had made the internal monitor a true-CGA. Composite creates weird artifacts on certain colors.

    But, once you get past that, it’s a fabulous machine. Also, setting DOS to black & white with the “mode bw80” command helps with the screen. The amber display is very nice. [quote]

    Dead easy to fix, in the CGA card just snip the resistor that introduces the color subcarrier to the composite video out (it feeds with others the base circuit of the video output transistor) , and the artifacts seen on the amber monitor vanish.

  7. #7

    Default

    Really? Cool! Which resistor is it? A picture would really help.
    Compaq - “It simply works better”

  8. #8
    Join Date
    May 2006
    Location
    Melbourne, Australia
    Posts
    6,251

    Default

    Quote Originally Posted by ButINeededThatName View Post
    2) Track down the system board from an XT-286 (or alternatively the later revision system board from an AT, both should still fit), ...
    The following measurements may prompt you to do further research.

    12" x 8.5" = IBM PC (5150) and IBM Portable PC (5155) and IBM XT (5160) motherboard [As measured by me.]

    13.8" x 12" = IBM AT (5170) motherboard - type 1
    [As measured by me.]
    13.8" x 9.4" = IBM AT (5170) motherboard - types 2 and 3
    [As measured by me.]

    13.04" x 8.57" = IBM XT-286 (5162) motherboard ????
    [Unconfirmed. I do not have one to verify.]

  9. #9

    Default

    Quote Originally Posted by compaqportableplus View Post
    Really? Cool! Which resistor is it? A picture would really help.
    I'm travelling, but when home I will look it up. If you look at the schematic for the IBM CGA card, on minuszerodegrees, you will see that the sync pulses, the r,g b and I signals and the color subcarrier signals are mixed into the base circuit of the video output transistor (the only transistor on the board as I recall), simply disconnect the resistor that couples in the subcarrier, it's easy to see on the schematic.

  10. #10

    Default

    Quote Originally Posted by Chuck(G) View Post
    Why not retrofit it with a modern nATX board, power supply and LCD monitor? You should have more than enough room to do it.
    I'd really like to swap out the monitor in my 5155 for an LCD, I'm not keen on the composite due to my eye sight, Other than the monitor i'm happy with my 5155, While out shopping a few weeks ago i was looking at one of those POS type LCD's above the counter, It was a "Wincor Nixdorf" and showed lovely clear text / pictures and wondered if one of those could be used, I've seen them on Ebah at a reasonable price.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •