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  1. Thread: Dummy Load

    by modem7
    Replies
    12
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    239

    I have seen that '50W 5ohm resistor' specified at...

    I have seen that '50W 5ohm resistor' specified at [here], but not specified elsewhere.

    A 5Ω/50W resistor is going to be unsuitable for some power supplies. For example, putting one on the +12V...
  2. That is probably the keyboard doing a self test...

    That is probably the keyboard doing a self test after receiving +5V.
  3. Replies
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    Take a look through the XT compatible memory...

    Take a look through the XT compatible memory cards at [here].
    Having a very quick look there, I see that the AST Rampage! (as an example) offers both conventional and EMS memory.
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    A converter for an AT class keyboard, such as the...

    A converter for an AT class keyboard, such as the one at [here], is something that you may want to consider.
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    78

    The drive's electronics are not sensing that the...

    The drive's electronics are not sensing that the spindle is spinning. That could be because the spindle is not spinning, or the spindle is spinning but there is faulty electronics.

    Do you hear the...
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    99

    See the photos of electrolytic capacitors at...

    See the photos of electrolytic capacitors at [here]. By "triangles", I presume that you are referring to the triangular segments shown in the second and third photos. If you are, then the 'triangles'...
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    You are not seeing any issues at all using 360K...

    You are not seeing any issues at all using 360K floppies, so this does not sound like a 'dirty heads' issue.

    What is the background of the subject drive?
    * Was it working with 1.2MB floppies...
  8. I am not following you. The parity calculating...

    I am not following you. The parity calculating hardware (for motherboard RAM) is elsewhere on the motherboard with the piggyback DRAM's in the 'parity' column simply storing the output of the...
  9. In case you did not see it, mentioned at [here...

    In case you did not see it, mentioned at [here] is the availability of prebuilt AT2XTKB (and some variants) on eBay.
  10. Some other issues: * The RAM on some network...

    Some other issues:

    * The RAM on some network cards does not appear in the motherboard's memory space until the driver for the card is loaded. Therefore, if the driver is not loaded,...
  11. C5 and R9 run from ground to +5V. When you have...

    C5 and R9 run from ground to +5V. When you have the keyboard plugged into the (unpowered) motherboard, measuring the resistance across C5 (or R9) is also measuring the resistance of the +5V on the...
  12. Replies
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    In the past, I have tried to fit various...

    In the past, I have tried to fit various half-height hard drives under the two floppy drives, but from memory, there are issues like the screw holes not lining up.
  13. Consider too the option of an AT class keyboard...

    Consider too the option of an AT class keyboard together with an adapter like the one at [here].

    BTW. I updated the circuit diagram even more.
  14. Replies
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    272

    As far as I am aware, the subject card will...

    As far as I am aware, the subject card will simultaneously support up to two floppy drives and up to two hard drives.
    The limitation you write of sounds like the limitation of the 5170's...
  15. Replies
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    Further to last: I am "jumping the gun" here....

    Further to last:

    I am "jumping the gun" here.

    If, via what I suggested, it is revealed that the controller is overloading the PSU, then there are many components on the controller that can...
  16. Replies
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    Welcome to these forums. By your "The PSU...

    Welcome to these forums.


    By your "The PSU starts", I am assuming that you are basing that on the fact that the PSU's fan is turning.

    If so, then here is what I think is happening:
    * There is...
  17. I am very experienced in 'recreating' circuit...

    I am very experienced in 'recreating' circuit diagrams. But it is still easy to get confused. For example, this morning, I realised that I had resistors R4 and R6 swapped. I updated the diagram.

    ...
  18. On that subject, after a prompt weeks back from...

    On that subject, after a prompt weeks back from member Malc, I did some more experimentation, and I now have a VCF XT-IDE card that appears to 'play nice' with the stock IBM BIOS ROM's on an IBM 5170...
  19. Suggesting that when the keyboard is attached,...

    Suggesting that when the keyboard is attached, the motherboard is seeing an AA byte from the keyboard.


    First, look at [here], the circuit diagram for the keyboard that IBM supplied with the IBM...
  20. That is odd. I would have thought that at least...

    That is odd. I would have thought that at least one the two motherboard you have used would have displayed a keyboard related error.

    If you remove the keyboard, does the POST display a keyboard...
  21. Some keyboards (perhaps most) do some sort of...

    Some keyboards (perhaps most) do some sort of self test as soon as they receive power, with that self test momentarily flashing on the LED's.

    With the keyboard disconnected from the computer,...
  22. If you are using IBM software, the author is...

    If you are using IBM software, the author is probably assuming that only IBM options are used, e.g. for base memory, settings of 256K, 512K, and 640K.
    I see that GSETUP.EXE has only 256K/512K/640K...
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    If you look at the memory map at [here...

    If you look at the memory map at [here], a start of C0000 will be a problem if your IBM 5160 has an EGA or VGA card.

    A start of C8000 will be a problem if you have one of the VGA cards that has a...
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    I have added a couple of new sections to the end.

    I have added a couple of new sections to the end.
  25. Replies
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    On the DataExpert EXP8049 motherboard, the...

    On the DataExpert EXP8049 motherboard, the external battery header, J1, is used for both an external battery, and as required, to clear the 'CMOS setup' data. User's manual at [here].
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