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This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Rule 1: Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Rule 2: Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Rule 3: Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
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  • Use the Private Message system for posts that are targeted at a specific person.


Rule 4: "PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
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Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Rule 5: Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
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Repaired 5160 XT after -12V short

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    Repaired 5160 XT after -12V short

    I want to give a big thanks to the maintainer and contributors of the minimum diagnostic guide at minuszerodegrees.net.
    This guide provides exactly the information and step-by-step guidance I needed to repair my broken IBM 5160 PC/XT.

    For the statistics: C58 was shorted on my mainboard.

    In case anyone is interested in the details:
    When I turned on my old XT for the first time in two years, exactly nothing happened. No sound, no lights, no fan. Upon closer inspection, I could see the power supply fan barely starting to turn at power-on, followed within 0.5 seconds by a click sound (as from a relay), then nothing.

    I went about randomly disconnecting things and measuring voltages. Pretty soon I came to the incorrect conclusion that my power supply was broken.
    While searching the Internet for ways to replace the power supply, I stumbled accross http://minuszerodegrees.net/5150_516...iag_config.htm. The first sentence of that page "You are here because your IBM PC appears to be dead" had an immediate calming effect on me, like clearly this must have been written by someone who already knows what the problem is, and who will now explain the problem to me in simple words that even I can understand. And indeed this guide turned out to be everything I was hoping for. I quickly learned that a PC power supply can not be tested without an adequate load. Then I learned how to confirm that my power supply was in fact still fine, and that the problem was in the +/- 12 V lines on my mainboard. Indeed my multimeter measured 0.1 Ohm between -12V and GND. And upon visual inspection of C58, I could see just a tiny dark spot on the capacitor.

    So I cut off C58, which eliminated the short in the -12V line. I decided to replace it with an aluminium electrolytic 10 uF 63 V capacitor. The guide recommends against resoldering on the board but I decided to try it anyway. Again I found that I was wrong and the guide was right: the solder job became a mess but in the end I got the new capacitor sort of soldered onto the pads.

    And now my XT is fine again. It boots, it runs, and the harddisk makes its little musical sounds.
    I'm very happy now. So thanks!

    #2
    Welcome to these forums.

    It is good to hear that you got your IBM 5160 operational.

    There is lots other 5160 information at minuszerodegrees.net, kind of acting as a self-serve. For 5160 information beyond that, don't hestitate to open another thread. There are plenty of people here who know lots about the 5160.

    Your 'C58' experience has been added to the list at [here].

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      #3
      Kudos to singlethread for the excellent description of a very common problem that is so often misdiagnosed which can and does lead to confusion and unnecessary actions by so many with these older machines.

      And, of course, thanks again to modem7 for having compiled and organized this wealth of information known as minuszerodegrees. I know I have had to refer to this invaluable site countless times.
      PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

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