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Thread: IBM XT 286 5162 - 201 RAM Error / DRAM D41464C or Sprague 61Z14A075 61Z14A150 ??

  1. #31
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    Thank you all guys for your help and patience. After such a loooong time waiting to receive the new ISA POST Card, and after this whole pandemic , today it was the day I finally got the ERROR CODE.

    "03 02".

    Here's a picture:

    POST CARD ERROR CODE.jpg

    This 5162 motherboard comes with the original IBM BIOS "78x7460 IBM CORP 1981-1986" (and "78x7461" on U35 socket).

    As you can see on the image, the POST Card it's been placed on J8 Slot, just next to RAM slots.

    If I remove the Hercules Video Card, I get the exact same Error code.

    I've been checking the list of POST codes, and I'm not sure to understand which one could be the next step to follow, so once again, I'll really appreciate your wise suggestions.

    Hundred thanks!!

  2. #32
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    Also, I forgot to say that, as it keeps refusing to start the boot sequence, I got the error code without even video signal at all.

  3. #33

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    Do you own an EPROM programmer? I'd try pulling the BIOS ROMs and dumping them to see if they are still good. Or just burn a new copy of MR BIOS or something and stick it in there and see if it boots

  4. #34
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    Sure, I have one and I can try it. This same IBM 5162 U34 and U35 BIOS chips must be somewhere over here, right?? The error code aims to a corrupted BIOS chip?

    Cheers

  5. #35
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    Quote Originally Posted by Dani G View Post
    Thank you all guys for your help and patience. After such a loooong time waiting to receive the new ISA POST Card, and after this whole pandemic , today it was the day I finally got the ERROR CODE.
    "03 02".
    Your new (second) POST card is the same as the modern one pictured and described at [here]. So, "03" is the POST code that the 5162' IBM POST stopped at. The "02" is simply the previous code that was sent to the POST card; ignore it ('02' passed).

    Descriptions of POST codes for the IBM BIOS supplied in the 5162 can be found via the navigation of [minuszerodegrees.net][5162 section][POST - Codes]
    Because your computer passed by '02', the POST considers your BIOS ROM's to be good.

    The description for '03' is "Verify shutdown byte in 146818 RTC chip". So, the POST went to test a particular RAM address in the 146818 RTC chip, and that test was unsuccessful. The 146818 chip may be faulty, or perhaps what is faulty is the supporting circuitry for the 146818.

    The '03' matches well with the failure of the PROTECTED MODE CPU test that you observed earlier, in the Supersoft/Landmark diagnostics (thread post #17).

    We have had members of these forums report a faulty 146818 RTC chip. If it is within your ability, perhaps try replacing it, ideally with one known to work.

    Beforehand, I suggest that you take a good look around the 146818 RTC chip (MC146818, near the end of slot #2). You may see a problem.

  6. #36
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    Awesome!!

    After a close inspection of the area, I've noticed about this little shiny buddy you can see on the images. I don't know what kind of component is it, could be some kind of capacitor ?, but I can read "25060Y" or "25069Y".

    Have a look:

    IMG_20200604_193058.jpg IMG_20200604_193124.jpg

    IMG_20200604_193125.jpgIMG_20200604_193423.jpg

    IMG_20200604_193434.jpg

    The thing is that, this electronic component was glued to the mother board, and for some reason, now is not glued anymore (too much heat?).

    Other than that, there's nothing more around the area to be suspicious about, so definitely, the problem is the 146818 RTC chip or this little shinny "25060Y".

    Should I directly get a new 146818 RTC chip and forget about the other component?

    I think so, and I can have the job done properly, but just would like to be sure before going ahead with it.

    I'm so happy now we are close!!
    YEEssSSs!!

  7. #37
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    Quote Originally Posted by Dani G View Post
    After a close inspection of the area, I've noticed about this little shiny buddy you can see on the images. I don't know what kind of component is it, could be some kind of capacitor ? but I can read "25060Y" or "25069Y".
    That is a 32.768 kHz crystal, designated Y2 in the IBM 5162, used in the oscillator circuit that 'ticks' the MC146818 RTC chip.

    Quote Originally Posted by Dani G View Post
    ... so definitely, the problem is the 146818 RTC chip or this little shinny "25060Y".
    If crystal Y2 was the only faulty component, you would see different symptoms.

    I am not saying that your MC146818 chip is definitely faulty, but based on the symptoms, and history, I think that there is a good chance.

    At [here] is an example where a MC146818 chip was found to be faulty. Note the same symptoms (03 on POST card [shown at post #11 of thread] and failure of PROTECTED MODE CPU test).

    I recommend that when you swap out the MC146818 chip, you also add an IC socket.

    A risk is that the MC146818 chip you acquire is faulty. Maybe some are advertised as tested. Maybe get more than one.

  8. #38

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    Quote Originally Posted by Dani G View Post
    ,,,The thing is that, this electronic component was glued to the mother board, and for some reason, now is not glued anymore (too much heat?
    Maybe it got replaced at some point and somebody glued it down for some reason, I just had a look at mine, The crystal is not glued and has the markings " 32768 ".

  9. #39
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    Yes, it could be replaced at some point, so I'll forget about the crystal by now.

    About 146818 RTC, what you've said seems absolutely right, basically because you've told me about it before getting the Post Card Error code. I just got that couple of MC146818AP chips you can see here:

    NEW RTC chip.jpg

    I will receive them in the next week/2 weeks, so I hope I can soon inform about a happy ending. Sure, I will have an IC socket installed.

    I'll update soon!

    Thanks again, wish you all a great weekend!!

  10. #40
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    FIXED!!!!

    Thanks to you all my friends.

    I got a socket installed and put the new MC146818AP chip on the motherboard, and the boot sequence of my IBM 5162 started again at the first attempt.

    All RAM was detected and cassette Basic showed up.

    Here's some pictures of the new chip:

    MC146818AP-A.jpgMC146818AP-B.jpg

    And here's the boot sequence:

    Boot sequence.jpg

    So, this is definitely a happy ending!!

    Best wishes to everyone and, if you are in the right side of the world, have a great summer!!

    ... AND THANKS AGAIN!!


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