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

Toshiba T1200 schematic

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

    #16
    Toshiba T1200 Power Board

    Here is a photo of the main power board for the Toshiba T1200.
    All of those elctrolytic caps must be replaced and I have also highlighted 2 SMD tantulum caps which
    also must be replaced. The large one is 10uF 16V and the smaller one is 3.3uF 16V. You can use standard
    electrolytic caps to replace the SMD tantalum's, if your OCD will allow that Just shorten and bend the legs
    into an L-shape and solder to the pads.

    I don't use hot-air guns to remove SMD caps, usually when they leak they are very easy to gently twist and pull
    away if you heat one side with an iron. The round SMD caps are very easy to remove without any heat by gripping
    them with some long-nose pliars and gently twisting them off in a circular motion. I very rarely rip the pads
    using this process if I'm careful enough. In fact, using hot-air on SMD caps will cause the pads to lift.
    The board can then be cleaned with IA and the pads re-tinned with some solder.
    Attached Files
    Last edited by rimmeruk; September 22, 2020, 01:02 PM.
    "If it ain't broke, fix it until it is"

    Comment


      #17
      rimmeruk,

      There was one cracked tantalum cap on the 1200ís PSU board I replaced and I did check the other and it seemed fine, but maybe it isnít.


      And yes, I agree that things can get overlooked quite easily. Iíve done it many times and still do occasionally.


      Also, something I want to reiterate; I was in no way claiming above that a Compaq has never broken and that they are 100% immune to problems, that would be silly, but I can genuinely say that I have never had a major issue with any SLT and I have had one of them for almost 10 years now. Again, not to say one could never malfunction, but they are definitely more reliable than some of the others.


      And another thing I want to reiterate, Iím in no way saying I am the ďbestĒ at repairing vintage computers, and I hate arrogant people that feel that way. There are many people on this forum and elsewhere that are far more experienced than I. Iím always eager to hear advice from other people that repair this stuff. The only point I was making above is that I have fixed a few of these things before.


      I am very happy to hear some of my posts have helped you.


      Thanks for that photo. I did have a chip unsoldered from the PSU board in that machine though, so Iíd have to dig those parts back up and reinstall that chip to do any testing.
      Compaq - It simply works better

      Comment


        #18
        You're welcome, I don't believe anyone or claims to be an expert

        There are even more SMD caps on the main logic board to replace, it's a pain in the ass job when you start, but the reward is worth it guess.
        "If it ain't broke, fix it until it is"

        Comment


          #19
          I'm in the same nightmare on a T1100 repair. I see than T1200 sound difficult to fix as well.

          The "power supply" (I'd rather call it a DC-DC converter) that I tested (see my post) actually seems fine, le'ts say acceptable, even with stock capacitors which are extremely high quality + all tested ok.

          I believe, as CompaqPortable does, that something ELSE than the powersupply dies in those with time passing by.

          I've located a malfunction in the TTL logic ( 74HC245 HC373 ) close to the CPU.
          Still a bit early to say exactly what the problem is, but i'm closing in. It's also likely that is is old/failing powersupplies that kill part of the logic.

          Comment


            #20
            Can't find your post. I've attempted a repair on a T1100 but in the end I just had to source a new mainboard, too much corrosion and track damage.
            The faults are caused by caps electrolite or battery acid eating away tracks or shorting the components.
            The IC's in Toshiba's and Compaq's are of a very high quality and reliabilty, they very very rarely just fail. Unfortunately it's the
            capacitors and batteries that have a short shelf life and ultimately destroy every other component and track connected to them.
            This is mainly the result of someone powering them up after they have been left unpowered for years and without inspecting the board first
            or using a current limiting power supply
            "If it ain't broke, fix it until it is"

            Comment


              #21
              Yes I'm afraid I'll have to source a mainboard as well

              I've really done EXTENSIVE research , but because of really minimal NiCD leaks on top of the bus controller, it seems some tracks are either shorted or behave completely wrong, I also believe part of the problem is UNDER those smds, and I think it's hopeless (but see below)

              The board looks clean visually, but even after multiple washes, there is something wrong in something that can't be seen even with my microscope.

              Some tracks look more green than gold (under the varnish), which doesn't seem right.
              It's really a vicious fault, that really can't be seen, but it's dead (reports "NO KEYBOARD" error all the time, frustrating because apart from that it boots and works...).
              But no keyboard

              I'm giving up.

              I will keep it for parts,
              Last edited by CedsRepair; December 16, 2020, 12:21 PM.

              Comment


                #22
                Another question is

                Now that toshiba is officially defunct,

                Is there really no way to source technical doc from them/former employees or something ?

                In order for us entusiasts to keep their systems alive, we really would need schematic of their vintage systems, and I don't see why they couldn't share that info after 40 years for systems like 8088 laptops
                If we don't put our hands on schematics now, they'll more than likely be lost forever (if not already the case)

                Is there anyone who would be able to contact some former employee, or technician, or anyone that could maybe help raise the issue to whoever now owns the intellectual property of former toshiba ?

                On my side, I've just emailed some press person at Dynabook.

                I could probably fix my T1100 motherboard if I had a T1100 schematic. Same for that other guys with his T1200 problem.
                T3200 would also be nice.
                Anything below Pentium for example...
                Last edited by CedsRepair; December 16, 2020, 12:35 PM.

                Comment


                  #23
                  Have you tried an external keyboard or another keyboard cable ?
                  As for the schematics, you'd have trouble getting them for most modern laptops. All the design sheets and schematics for your T1200 will
                  be long gone and destroyed along with the systems they were designed on. Why would Toshiba bother archiving them and then making
                  them available for free for anyone who asked. There are probably only a dozen or so people who actually own a T1200 now.
                  It's not that difficult to reverse engineer the circuit yourself, but it's also no fun task. The problem is not having the schematics, it's
                  not having the discontinued components and IC's. Toshiba used their own Microcontroller ic's for the power management and
                  controllers which communicate with the BIOS and ROM.

                  All I can suggest is do more checks around the board with your meter. From my experience you will fix one fault only to find more
                  and more faults will eventually surface.
                  "If it ain't broke, fix it until it is"

                  Comment


                    #24
                    Regarding the schematics, I think that Toshiba beeing Japanese (especially those vintage models) there is no doubt their document management is flawless and that these schematics are easy to find if someone with the rights credentials starts to look for them, for us, vintage afficionados.

                    I don't see a reason why they wouldn't, the problem is really finding an insider to start with.
                    I got no answer back from Toshiba America PR contact, which is no surprise, I would have preferred that they at least answer with a "no".
                    I believe it would be much easier going thru a former employee that probably has a copy of old things rotting in a drawer.

                    Regarding the repair process you are absolutely right, most repairs end up finding multiple problems, I keep telling that to people who want me to fix their old Sega Genesis or Lynx because I have the right equipment... They seem to believe everything is as simple as in youtube videos, that I'll desolder two capacitors and it'll magically work again, that's not how it works as most of us know (and few youtubers show.)

                    Caring about vintage laptops is even more difficult (I think) for the reason you stated, heavy use of customs ICs and single ICs doing a lot of things.

                    I'll continue to harass Toshiba or their affiliated companies

                    Comment


                      #25
                      Originally posted by CedsRepair View Post
                      Caring about vintage laptops is even more difficult (I think) for the reason you stated, heavy use of customs ICs and single ICs doing a lot of things.

                      I'll continue to harass Toshiba or their affiliated companies
                      Well even with the schematics for the power and logic boards, you are going to have a very tough time finding replacement screens for these kind of laptops.
                      The screens are not easily repaired, the power boards can be bypassed and re-wired quite easily. I've decided to retro fit more modern boards and easily available
                      VGA panels from old monitors into some of older laptops that I have. Most of the screens I replace the invertor and failing tubes with LED strips. For the boards I use
                      those mini AIO dos systems and custom wire all the ports to the original ports. This way I get to use a more modern reliable system in the original retro case.
                      The old laptop cases are huge in comparison to the AIO boards with lots of space left for the Arduino PS2 keyboard controllers which I use to interface the old ribbon
                      cables from the original keyboard. Looks messy with all the re-wiring but with the case closed it looks real nice. The T1200 has a very nice ALPS keyboard and
                      is great to use. Unfortunately I don't have the pleasure of the blue on white screen anymore, so the 256 colour TFT panel I retro fitted will have to do for now

                      You can pick the AIO dos system boards from a great seller in germany on ebay:
                      https://www.ebay.co.uk/itm/17-43CM-T...1/312576885910

                      I will probably post a topic with some photos later this year when I can recover from all the binge drinking from last year
                      Last edited by rimmeruk; January 2, 2021, 03:25 AM.
                      "If it ain't broke, fix it until it is"

                      Comment

                      Working...
                      X