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

ThinkPad 755CD Won't Boot - Speaker Light Flashes

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

    ThinkPad 755CD Won't Boot - Speaker Light Flashes

    I acquired a ThinkPad 755CD from someone this week. He told me it was broken and described the symptoms but it was cheap enough I decided to take the chance.

    The issue is that nothing shows up on the screen, not even BIOS. When i power it on, I can hear the HDD spin up, the HDD spindle operate for just a second, the CD drive seems to go through a boot process and I'm able to open the CD tray. When i hit the function key and one of its corresponding keys up top, I hear a beep that seems to come through the speakers.

    I've soured the internet for information and have found a few posts. This actually seems to be a fairly common problem so I'm hoping one of you seasoned pros can share some of your unwritten knowledge with me.

    So far I've tried booting the computer a bunch of times in a row. I've tried this fast, slow, waiting, not waiting etc etc. There's no other way I can do this. I read this somewhere as a possible solution. I've also tried hitting the reset button on the back panel with a pen tip and holding that down for 10 seconds while flipping the power button a few times.. Read that somewhere else. I've also tried opening the computer and removing the HDD, RAM, etc. The battery is already gone, I can see some mild corrosion on one of the connectors so it makes sense that it would have been removed and should have no effect on the computer's ability to operate (as long as it's plugged in). I also tried toggling the external monitor / display off function keys a bunch of times in case the issue was that it was setup to show on an external screen only.

    The guy I bought this from says it worked fine for years and then one time, after having let it sit for about 6 months, stopped booting. He has no further info for me.

    I see motherboards for sale on eBay, I'm wondering if that's the best next step. I'm not sure how to install one but I'm sure it can't be too hard.

    What do you guys think? I really hope I can salvage this thing.

    #2
    Hello there!

    I'm not an expert in laptops, but try the following: Connect an external monitor, and turn on the computer. After that, try pressing the monitor/display key. If the video signal is visible on the ext. monitor, it could be that the LCD screen is broken. If not, then probably the video chip or the motherboard is broken. Also, when turning off the laptop, does it beep? All (old) ThinkPads make a beep every time they turn off, so if yours doesn't, then probably the motherboard is dead. So yes, probably you'll have to replace it (Unless you're able to find out what's wrong with it).

    If it helps, here's a video of a working ThinkPad 755CD (and shutdown), that way you can see what's supposed to do

    Comment


      #3
      I have a 755CD and i fixed the issue, there is a board that is connected to the screen and the mainboard, iirc it's the mpeg video decoder or something related to video processing, that board has caps that leak and fail, giving the exact issue you have. I fixed it replacing all the caps and cleaning the board to stop corrosion if any.

      Comment


        #4
        Not that it matters, since the OP already got his system fixed and posted up on eBay, but I just acquired a 755CD last weekend for beyond cheap (maybe 5 bucks? it was part of a lot of other vintage stuff). Anyways, my system would POST, enter BIOS, and that was it. Nothing beyond that, not even an error message. The battery was corroded to hell, and I've noticed that darn near EVERY SINGLE ROUNDED EDGED BATTERY leaks like the Titanic. Amazingly, I was able to successfully rebuild one of these batteries, but in the future, I stay away from them.

        With that said, I opted for a system board replacement. The system board is exactly like what you'd find in a 755CE or 755CX, depending on processor. Mine had a Pentium 75, so obviously, I'm saving that for a 755CE upgrade. Popped in a spare 755CX system board and reattached all the daughter boards. There's the mWave board, the DC-DC board (mine had the Lithium Ion DC-DC with the LiIon battery connector), and then a riser for the MPEG board (which also depresses the keyboard suspend switch and has its own switch on top). It's a little tricky taking apart, and past experience has told me to be VERY careful with some connectors (cold solder joints). Did this and the system works great, with one caveat - the battery connector has so much corrosion from the leaking prior battery, that even sandpaper couldn't get it all off. I ordered one that I'm waiting for, as I'll be using this with LiIon batteries.

        As far as leaking caps, that wouldn't surprise me, but these boards seem to be fairly resilient. The only complaints I've had are with the rounded edge batteries leaking. 755C/750 series batteries seem to be okay, and for whatever reason, I've never noticed any leakage. And for the curious who want to rebuild these batteries, they use Toshiba cells, but the proper cell is a 4/5A battery (like the Sanyo HR-AUL).
        IBM Computers: 5150 (16-64K, 64-256K), 5160, 5161, 5162, 5170 (regular and Tempest), Option 370 16 bit, PC Convertible
        PS/2 Machines: 30, 40SX, 50Z, 55SX, 60, 70, 77 (Lacuna & Bermuda), 80, 85, 90 XP, 95, "E"
        Vintage ThinkPads: 300, 360C/CE, 510CS, 560/E, 600E/X, 701C/CS, 700, 720C, 730TE (tablet), 750C/P (color and tablet models), 755C/CE/CD/CDV/CX, 760ED, 765L, 770
        Vintage UNIX workstations: 2/120, 3/75, 3/60, SS 2/5/20, U2 Ent, HP 715/100, several RS/6000s

        Comment

        Working...
        X