Announcement

Collapse

Forum Rules and Etiquette

Our mission ...

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.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • 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.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


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.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Help locating new transformer for 8 inch floppy power supply.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Help locating new transformer for 8 inch floppy power supply.

    Recently, among several floppy read failures, I began to notice an acrid smell coming from my 8 inch floppy disk enclosure. I opened the enclosure and saw that the source of the smell was the floppy power supply transformer which was now discolored and misshapen. Wondering if I had a shorted component on the circuit board, I tested and found that the board itself was OK. The transformer had just decided to short out on me. In looking around for a replacement transformer, I came across pictures of my power supply in an XOR system. I will try to upload pictures of the power supply and schematic with this thread.

    Does anyone know how to locate a suitable transformer that has these two secondaries. When I have tried to search for a match, I end up on some trasformer website and then immediately get lost in the forest of transformer options before finding anything that is even remotely close to what I need.

    Any help would be greatly appreciated.

    Phillip

    CAGE.jpginside_rear.jpgPower Supply Schematic.jpg

    #2
    Phillip, switching PSUs have pretty much obsoleted the linear ones. Your best bet is to replace that single transformer with two separate ones, which will allow you to keep your current PCBs. You didn't state if you were in a 120VAC or a 240VAC mains country--your current PSU can be wired for either voltage. You could also find a couple of switching supplies to give you similar output.

    Take a look at Jameco.com.
    Last edited by Chuck(G); August 26, 2015, 06:52 AM.
    Reach me: vcfblackhole _at_ protonmail dot com.

    Comment


      #3
      >I began to notice an acrid smell coming from my 8 inch floppy disk enclosure.
      >I opened the enclosure and saw that the source of the smell was the floppy power supply transformer which was now discolored and misshapen.

      Philip, if you are using 120VAC I noticed in your schematic the primaries are switched in parallel. If that has a switch, you might want to check that switch with an ohmmeter to make
      sure it does indeed add them in parallel. Parallel windings provide more current capability. If it's been running on one primary due to a defective switch or in
      my case the switch mounting screws had come loose, the functioning primary has to provide twice the current and will run warm and discolor over time. If the switch
      was wrong, you could try running it again with them connected properly in parallel. AC line transformers are very durable and forgiving. However, yours might
      have gone beyond that point.

      Larry G

      Comment


        #4
        Thank you for the replies.

        Chuck, I am in the USA so the supply is wired 120vac. I will probably go to a switching supply. I had hoped to find a similar transformer for originality, but by the time I find two seperate transformers, I will probably end up spending nearly as much as a new switching supply will cost. I have found a supply on eBay that provides all of the voltages at sufficient amperage for 39.99, so I will go ahead and get that.

        Larry,

        Thanks for your input too. The configuration of my supply was hard wired with no option switch. There are two black and two red wires on the primary side and the supply was wired from one red and black pair. I stripped the shrink wrap tubing off of the other red and black pair and tried them but the heat damage to the transformer was too extensive. The transformer simply began to overheat on the second primary winding as well.

        Thanks again to you both.
        Phillip

        Comment


          #5
          It pays to mention that transformers rarely fail without something causing excessive current draw, often the filter caps drying out and shorting.

          It your case it sounds like it was never wired correctly in the first place, with only one primary hooked up.

          A switcher is a good solution, but if you're looking to preserve a vintage piece their are many folks who will rewind or "clone" vintage transformers. I've used Heyboyer (Michigan, USA) in the past for some vintage vacuum tube gear. It's a more expensive option.

          - Gary

          Comment


            #6
            Transformers that are subjected to temperature extremes can often develop shorts in the windings. Like anything electronic, it pays in the long run to keep everything cool. Your choice of a switcher will greatly reduce the heat in the enclosure.
            Reach me: vcfblackhole _at_ protonmail dot com.

            Comment


              #7
              >There are two black and two red wires on the primary side and the supply was wired from one red and black pair. I stripped the shrink wrap tubing off of the other red and black pair and tried them but the heat damage to the transformer was >too extensive. The transformer simply began to overheat on the second primary winding as well.

              Just to clarify, the red wires should be tied together and the black wires together and AC applied to both primaries together. One primary by itself will overheat. The current is split in half when paralleled together and the output power is doubled with less drop across the transformer from primary to secondary which generates the heat.

              Larry G

              Comment


                #8
                If you disconnect the secondaries from the power supply board and apply line voltage to the transformer--regardless of how the primaries are set up--and it heats up, it's toast. A transformer with no load should not heat noticeably at all.

                If it heats up only when connected to the power supply PCB, then your problem is in the power supply itself, not the transformer.
                Reach me: vcfblackhole _at_ protonmail dot com.

                Comment


                  #9
                  >If you disconnect the secondaries from the power supply board and apply line voltage to the transformer--regardless of how the primaries are set up--and it heats up, it's toast. A transformer with no load should not heat noticeably at all.
                  >If it heats up only when connected to the power supply PCB, then your problem is in the power supply itself, not the transformer.

                  Yes I agree totally with that test. It's a shame if it burned up because only one primary was being used improperly wired alll these years. The schematic shows it should have had both primaries in parallel.

                  Larry G

                  Comment

                  Working...
                  X