Compaq Contura 3/25C 80386 Laptop

4.00 avg. rating (84% score) - 1 vote

I recently picked up a free Compaq Contura 3/25c, a very old IBM-compatible laptop computer from the early 1990s, with a 25MHz 80386 processor, 4MB onboard memory and 3.5in 1.44MB floppy drive. The original 120MB hard drive has been removed by the previous owner. The laptop is also in very bad shape, with dust all over the place and the LCD panel removed:

The laptop must have looked like this when new with the 8.4 inch black and white LCD:

I was trying to make it boot up by connecting an external monitor to the VGA port when I noticed that the VGA port is actually keyed via pin #9. No modern VGA cable would fit into this port until you break pin #9 on the cable or punch a hole on pin #9 of the port. Since there is actually no need to key a VGA DB9 connector because the shape of the port would prevent you from inserting it upside down anyway, later VGA ports used pin #9 as an optional +5V DC source.

CMOS Battery

The unit boots up with a “RTC Lost Power” error message (see this for a full list of Compaq POST error messages). This is quite common with old laptop when the CMOS battery finally dies after a few years. So I opened it up in order to replace the battery:

The laptop is using a CR2430 lithium coin battery placed in a socket to facilitate replacement. There is even a warning, in various languages, telling you about danger of explosion if the battery is incorrectly replaced. This surprised me, since modern laptops would probably just have the battery soldered onboard. Some may feature a motherboard socket for the battery connector, but the actual connections to the battery are permanently soldered, which means some wire-cutting and soldering needs to be done if the battery ever needs to be replaced. This is a CMOS battery from a newer laptop:

I quickly ordered a pack of 5 CR2430 cells for a cheap price from eBay. Notice the funny English on the packaging. Whoever typed this probably had no ideas what it means:

BIOS Setup

With the CMOS battery replaced and a PS2 keyboard connected, I started the machine. Although many old laptops and PCs do not have an onboard BIOS and require the use of startup disks containing the BIOS utilities to change system settings, this machine has one, available in several languages, accessible via F10 at startup:

There are 2 startup disks for this laptop, formerly downloadable from Compaq website:

  • Disk 1: BIOS setup utility
  • Disk 2: Diagnostic utility

However, these downloads were removed when Compaq was merged with HP in 2003 and a lot of legacy support was gone. Although I eventually managed to find the disks with the help of, disk 1 comes with no COMMAND.COM and boots up to a DOS error “Bad or Missing Command Interpreter” error message. I fixed the error by putting MS-DOS 6.22 on it. The images for both disks as well as the original tool to create the disks (SP2054.exe) can be downloaded here. You will need WinImage to write the images to floppy disks.

Unlike the motherboard SETUP, the SETUP utility on the disks uses graphic mode and takes a long time to start up:

Installing the hard drive

Since the original hard disk has been removed, my next task is to install a 2.5inch IDE hard drive before the notebook can be used for anything useful. Keeping in mind that laptops of this generation only use CHS addressing and do not support hard drive more than 512MB due to the 1,024 cylinders limitation, I have chosen a 270MB IBM DHAA-2270 hard drive:

Still, installing the hard drive turns out to be no easy tasks as the BIOS only supports a limited number of hard drives types (which does not include my drive). There is also no support for auto detection or user-defined types:

Interestingly, types 65 and 66 are empty, indicating that they are custom types and can be configured by either re-programming the BIOS as suggested in this forum discussion, or by writing a tool that modifies the BIOS hard disk type table stored in memory and hope that the BIOS will recognize the changes. Either way, it’s a shoot in the dark as I could find no instructions on flashing this laptop’s BIOS, and there is also no documented address where I can hope to find the type table.

However, there is an easier way by using a drive overlay such as ANYDRIVE or EZ-Drive. The trick is to specify a hard disk type in BIOS where the number of cylinders, heads and sectors is smaller than the actual value so that the BIOS will not report an error on POST and accept the hard disk. Once then, boot from a floppy disks with ANYDRIVE to set up the disk overlay, which will overwrite BIOS Int 13h (which is used by DOS to query hard drive info) and respond with the correct disk geometry values. Run FDISK to setup the hard disk and you will be able to use the full capacity.

This will work with DOS and Windows 3.1 or older which relies on Int 13h to access the hard disk. Operating systems such as Linux and some disk utilities may query the hard disk directly, resulting in possible data loss with the overlay installed. In Windows 3.1, 32-bit disk access must be turned off, otherwise Windows may also query the hard disk directly, resulting in similar problems.

Transferring files using Norton Commander

With the overlay installed, all existing data on the disk is lost and some PCs may also fail to recognize the drive. Since I do not want to copy data and programs to the laptop using floppy disks, the only other way is to use a serial or parallel cable, with the help of Norton Commander 5.0 Link utility.

Note that you cannot simply use a male-to-male serial or parallel cable, but rather a null modem or a Laplink cable respectively. Since these cables are extremely over priced, I decided to go for soldering a null modem cable myself using the connectors available in my junkbox, and the pinout from here. With my other PCs running Norton Commander (NC) from within Windows 98 acting as Master, I am able to copy the data to this laptop (acting as Slave). At a maximum theoretical speed of 115200bps, made slower by the noise-sensitive cable disrupting the copy process resulting in several misleading errors “There is not enough room to copy…” from NC, it took half a day to copy DOS programs, games and Windows 3.1 to the laptop.

However, before I could think of some useful purposes for this laptop, it dies and fails to POST with no beeps and no display output. On every boot, the system simply hung after attempting to seek the floppy drive. There were perhaps several symptoms that the laptop was dying, for example the fact that I needed to press the POWER button multiple times (although the button itself is fine, as checked by a multimeter) to turn the laptop on and the wrong memory count of 21885KBytes extended memory in BIOS:

Since all basic troubleshooting does not seem to help and there are no user replaceable parts inside the motherboard, I eventually removed the hard disk and ran FDISK /MBR to remove the overlay, and toss the machine. Everything has its time, I guess.

UPDATE (Feb 2014)

A reader shared with me that he had a similar Compaq Contura laptop whose LCD had failed and displayed random patterns upon being turned on, although it still seemed to boot properly as the POST beep could be heard. After several debugging attempts, he finally managed to fix the issue and the laptop could boot to Windows 3.1 successfully. The LCD failure was due to a broken PCB trace resulting from an electrolytic capacitor leak (see the comments section of this article for further details).

The complete set of photos and videos demonstrating the disassembly, the failure mechanism of the LCD as well as several Windows 3.1 screens once the LCD has been fixed can be viewed here.

Thanks to Fabio for his sharing! I am sure this will help other people who are trying to keep their Contura laptops and other similar vintage computers alive.

4.00 avg. rating (84% score) - 1 vote


A tough developer who likes to work on just about anything, from software development to electronics, and share his knowledge with the rest of the world.

53 thoughts on “Compaq Contura 3/25C 80386 Laptop

  • January 11, 2012 at 8:26 pm

    This was my first laptop purchased circa 1995 when I was in my final years in the U. It's with a color display. At that time running on Windows 3.11.
    Loved that trackball though looked awkward at that time, it was easy to use.

  • January 25, 2014 at 7:14 pm

    Hello, I do not have the floppy drive for this contura 325, can you do an image of the hard disk for me? Thank you.

  • January 25, 2014 at 10:42 pm

    HI Fabio,

    I do not have the HDD image of this computer. You should be able to get MS-DOS 6.22 and Windows 3.1 on it without issues. You can get many old boot floppy disk images from

  • January 28, 2014 at 5:10 am

    Thank you for your attention, but I do not have the external floppy drive for contura 3/25. It is a special PCMCIA to floppy card.

  • January 28, 2014 at 10:17 am

    Hi Fabio,

    As a start you may want to put the HDD into another computer and put MS-DOS on it (via the SYS command, for example), together with other software and utilities. Once the hard disk is installed back to the laptop, it should be able to boot into MS-DOS, from which you can install Windows 3.1 and play with it.

    Have fun!

  • February 15, 2014 at 10:33 am

    Thank you for your advice. I bought an another contura with bad lcd screen, and it came with a pcmcia to floppy drive. I found two new boxes of 1.44MB floppy disks for sale, and now I am able to enter setup. Whoa! The contura with broken LCD has a working hard drive, and it boots up with a windows 3.11. With two conturas I did one, working very well. Only the hard disk drive seems that have some click sounds, maybe it will be dead soon. I only want do preserve the old technologies, because these items become very rare as the time goes by.

  • February 15, 2014 at 10:36 am

    Hi Fabio,

    Thanks for sharing :) Enjoy playing with the laptop. Let me know if you need any files or old software to play with.

  • February 18, 2014 at 1:58 am

    Okay, thank you. Now I am looking for a LCD screen for compaq Contura 3/20 (386 20MHz). Everything is fine but the screen. It does turn on, even the backlight turn on. But it shows only some big squares, like a chessboard. It is a monochrome vga display. I tried to disassemble it, tried to wash and dry the circuits (I have a lot of luck washing old circuits and then putting it in an oven to dry it) but it still does not work. The display works with 28 Vdc and this voltage is present, then I think is it dead. (its not broken). If you know how to fix it, can you advice me?

  • February 18, 2014 at 10:34 am

    Hi Fabio,

    How does the chessboard pattern look like? I can give some ideas if you can send me a photo of the LCD displaying squares and a high-res photo of the motherboard.

    Can you connect the VGA port at the back of the laptop to a monitor to see if you can have a video output? If so, the video controller is working fine and the problem may be with the LCD driver.

    If the backlight turns on and the DC voltage is correct and the LCD is not broken but only shows a chessboard pattern, try to identify the LCD controller/driver chip on the board. If you can identify the chip, try to search for the datasheet. Some chips have a test mode which will output some test patterns on the LCD. Usually, this mode is activated either by shorting a dedicated pin to 5V/GND or when some input signals are missing. If you can locate the controller chip, try to identify any short circuits. Old dirt or leaks from electrolytic capacitors on the board may have shorted something and enabled the test mode.

    With the laptop and LCD on, use a thermal camera or a cheap cellphone camera in video mode and point it close at the motherboard. Any shorts will result in heat and may be visible in the camera viewfinder. I used to identify shorts on old circuits this way.

    Last but not least, check the ribbon cable from the motherboard to the LCD. Tiny metal traces on it may have been broken after numerous opening/closing of the LCD panel, causing problems.

    Let me know your progress.

  • February 18, 2014 at 12:04 pm

    Hi MD. I did all your tests. I did test the flat cable before, and yes, there is video output in VGA port. Everything works fine.

    The backlight does not turn on, but This is a different circuit, isnt it? Maybe the cold cathode lamp is dead. Since you asked, I have never de-solder the flat cables inside the LCD. I had to do it to see the part number of the ICs, because they had a plasic housing over them. I disassembled everything and took photos and did make a video, they are here on my dropbox:

    As you can see in the video, the pattern is different everytime I turn the LCD on, not always the same. I found only the voltage multiplier datasheet, the other one I did not find (50003scc-s). I trie to resolder everything, but nothing seems to fix it.

    3/4 of the LCD borders have some ICs mounted over the flat cables, I thnk they are demuxes to excite the LCD pixels. You can see that the chessboard pattern seems to be mounted every demux, like some demuxes send blach and some demuxes sends white. can you notice that in the picture 2014-02-17 00.13.12.jpg?

    I measured the voltage over the capacitors, it has about 24.. 28V over them, some of them have 2V.. There is no test/example circuit on datasheet to show what voltage need to be on the capacitors (

    Thank you for your patience.

  • February 18, 2014 at 1:29 pm

    It is working now! I was checking the inverter circuit that turn on the LCD, and there is two potentiometers. One of them have 2V reference, and the another didn have this 2V reference. I checked the tracks and the track that brings the reference was broken due a eletrolytic capacitor leak. I just solder the two broken tracks and it did turn on! Check the last photos in my dropbox:

    There is still two lines that do not turn on, you can see at the photos. But there is no problem.. BUT if you know how to fix it.. :)

    Thank you very much, you were right. \o/

  • February 18, 2014 at 2:11 pm

    Hi Fabio,

    Thanks so much for your fast update and congratulations on getting this old machine working again. :) Your photos and your video are great too – it has been a long time since I last saw Windows 3.1 and MS-DOS on a monochrome LCD.

    After reading your first reply and looked through the photos, I did some research on the LCD panel of this laptop and managed to find some valuable information. I posted here in case it may be useful for others.

    The laptop is using the LM64P728 (139638-001) VGA panel. It is using the 65540/65545 integrated controller which will provide both output on the VGA ports and the LCD panel. The control interface is via a 15-pin connector (which can be seen in a few of your photos) and the communication protocol is shared between several other similar LCD models including the LM64P722 and LM64C08P made by Sharp.

    You can find the pinout of the 15-pin connector here: – it is for the LM64C08P but will be applicable for the LM64P722 and the LM64P728 too. The datasheet for the 65540/65545 VGA/TFT controller can be found here – it includes details about the communication protocol – which will be useful should you need to repair it again.

    Another company named RTD also created the CM110/CM112 controller, similar to the 65540/65545 controller. The CM110/CM112 supports the LM64P722 and LM68P728, together with many other color LCD panels too. You can find the datasheets below:

    A set of DOS tools were created by RTD to retrieve the LCD information and some diagnostics information. You can download it here – if you have time try it on your machine to see if it will work :)

    As for the 2 dead lines on your photos, it could be that the liquid crystals inside are already dead or inactive after a long idle period. Try to toggle the whole screen between black and white repeatedly and leave it like that for a while – it may revive the liquid crystals inside those pixels if they are not totally dead yet. Also use an oscilloscope to check for ripples on the power supply – it may cause problems with the sync signals, resulting in the loss of some lines. The latter case is however unlikely as your dead lines seem to be at fixed position.

    Again, great work on this laptop and thanks for sharing with me too!

  • February 18, 2014 at 8:43 pm

    Thank you very much for your research and your effort to help me. I have 3 contura laptops: 3/20, 4/20 and 4/25. The 486 are color displays and the 386 monochrome. The 386 disk have no badblocks, one 486 has a dead hard disk and a dead screen. The another 486 is working well but has a "clicky" hard disk. I am repairing and will keep these old computers in a special box, to prevent their contact from high temperatures and humidity.

    About twenty years did pass from the manufacture date, and I pretend to keep it a lot more, to show my grandsons how was the technology from the past.

    I will continue to search and buy for a few bucks all of these old machines. Please send me an e-mail to to keep in touch.

    Feel free to use my images to put on your blog, or if you need some pictures (even disassembled), I can take for you of the working system. It is very interesting.

  • February 18, 2014 at 9:07 pm

    Hi Fabio,

    Thanks so much for sharing too. Let's keep in touch. I will also continue to update my blog as and when I find interesting old machines to play with. :) It is great that you are maintaining these little old machines – they are made to last decades!


  • March 24, 2014 at 5:56 am

    This was an amazing read! I myself have two of these laptops, a 3/25 and a 4/25, both are defective. I bought the 3/25 as a parts machine for cheap, but as I hate to strip machines, I decided to keep it and fix it up. It is missing the keyboard and the cover, and the ribbon cable to the display is broken. Of course it came without a harddrive too. ;-)

    However, it does seem to boot as I can hear the BIOS beeps through the PC speaker. I did not yet try to connect it to an external display because of the keyed VGA port, as described here.

    I got the 4/25 later, it is complete but has a broken keyboard and power board, I tried it with the 3/25's power board and it boots fine to Windows 3.1 with an external keyboard. :-)

    These are great little machines, cheers to everyone who tries to keep them alive!

  • March 24, 2014 at 8:44 am

    Thanks for sharing with us. I love these little old laptops – they are great machines for experimenting with DOS and Windows 3.1. Let me know if you manage to get your 3/25 to do something useful after fixing the keyed VGA port :)

  • March 25, 2014 at 1:49 am

    I am glad to tell you the system is working! Today I attached it to an external display and it passes POST perfectly, except for the oh so familiar "RTC Lost Power".

    I tried a fix for the ribbon cable that consists of cutting off the broken connector, and then carefully sanding off the plastic insulation layer to create a new connection point. After doing so, the display lights up and the brightness/contrast sliders work fine, altough nothing appears on the screen. However, now that I know that the internals of the laptop are still OK, I'm confident I'll be able to fix that.

    I might eventually dedicate a website to these machines, so far I found out quite a bit that might be useful to other users and tinkerers alike.

    I'll keep you posted!

  • March 25, 2014 at 10:08 am

    Glad to know that your 3/25 is still in good health after so many years. Have fun with it! Let me know once your website is up – I will post the link to your website here for the benefits of others who are also interested in keeping these old machines alive.

  • May 4, 2014 at 9:07 pm

    I have one of those laptops, and the trackball i hate. I pretty much hate it because the mouse disappears whenever i move it. And, mine also runs Windows 3.11. I am booting it right row. (man those obnokios noises)

  • August 4, 2015 at 4:13 am

    All good day, I have a similar laptop, there was a problem with the dc-dc converter. electric diagramm be found anywhere else on the Internet can’t. At the moment I want to re-start the laptop HDD works audible as he reads the information, the monitor will not display information (no backlight). Can you help me? it is possible to measure the voltage on the 20 pin connector dc-dc converter? Not having electric diagramm very difficult to repair. Maybe someone knows where to apply power to enable the controller of the external monitor?

  • August 4, 2015 at 10:21 pm

    Hi Andrei,

    What do you mean by the dc-dc converter? If I understand correctly, your laptop screen backlight is faulty and you can’t read what is displayed on the internal LCD panel? Is there BIOS POST beep, floppy seek and hard disk activity sound after you boot?

    For the external monitor I think the default is to output a copy of the display on the internal LCD onto the VGA port. I will be 640x480x256 colors. Just use a standard VGA cable and see if it works. You may need to break pin #9 on the VGA cable as it’s keyed on the VGA port of this laptop, otherwise the cable won’t fit in. If there is no output on the port, it is possible that VGA output is not enabled on this port by default and you will need to press some keys on the keyboard. If that still doesn’t work, refer to the previous commented dated Mon. Feb 17, 2014 on how to debug the 65540/65545 VGA controller chipset – you can try to ground/connect certain pins in order to activate VGA output or display test patterns.

    You can refer to section 6 of the table (UPDATE (Feb 2014)) for some further information regarding LCD troubleshooting – a previous reader has contributed some useful diassembly videos/photos.

    Let me know if you need any info.

  • August 6, 2015 at 1:02 am

    Good day. thanks to which I replied, really want to restore this laptop.I got the laptop from the previous owner, he claims when he clicked to enable it, then heard the hiss with cotton in the top right of the laptop (that’s why I started the repair with dc-dc Converter: after you turn not, you will hear how the hard drive reads anything and everything. here is a picture Board of your monitor with comments: , the given image motherboard (reverse side): I now look carefully the previous posts, and do a similar action. I certainly doubt that the faults can be the same. I will be very grateful if you help run a vintage laptop. Wife told me I was a maniac :)

  • August 7, 2015 at 10:33 pm

    Hi Andrei,

    Thanks for sharing your progress with me and thanks for posting the detailed schema of the DC to DC converter and the disassembly photos. I have some suggestions below.

    A hiss from a power supply, in this case, the DC to DC converter, usually indicates that it is overloaded by a fault and operating at a lower frequency, hence causing the audible hiss sound.

    The most likely suspect I could think of is capacitors. Since you have replaced the through-hole electolyte capacitor and it still doesn’t help, perhaps there are other leaking capacitors as well. Do you have an ESR meter? If so you can check other capacitors, take note of the SMD electrolytics capacitors too – they have short shelf life and can leak without any visible effects.

    My experience with early laptops is that usually the VGA port outputs a copy of the internal LCD upon boot up without the need to press any key (Fn, etc.). In you case I think the problem of no VGA output is due to a hardware fault, rather than the requirement to press soft keys.

    The microcontroller / VGA controller on your photos usually have pins dedicated for the oscillators, do you perhaps have an oscilloscope or a frequency counter just to check that they are operating? If you have one you can also check the voltage rail (+5V, +3.3V) to see if it’s clean or contains ripples. Old capacitor may cause too much ripple on the voltage rail and affect the electronics. Meanwhile let me try to find the datasheet of your VGA controller and see if it could offer any help.

    The SMD10P05 MOSFET may not be faulty. I think the behaviour could be because of other components in the circuit. MOSFETs are unlikely to fail unless they were abused (subject to high voltages, etc.)

    One last suggestion, have you tried cleaning the board with a can of compressed air? This may blow off dirts, electrolyte leaks, etc that short the PCB tracks. It worked for me before in one of my old laptops.

    Again, thanks for sharing the detailed notes and keep me updated on the progress.

  • May 31, 2017 at 5:09 pm

    thanks ! i wake up an old 3/25 with your informations

  • January 11, 2019 at 5:04 pm

    Hi Guys!

    I bought a …almost destroyed 3/25 with Latin America Key Layout, no mouse, keyboard was not responding, no battery, no power supply. Since the monitor was totally damaged I use an external VGA monitor with no issues, replace the battery, refurbishing the keyboard, repaired the floppy drive and load DOS and some games and now is working fine. Thing is, can I remove completely the Monitor and use an external monitor? Or it will be end with any issues?

  • ToughDev
    January 14, 2019 at 10:55 am

    Nico, I don’t believe there will be any issues but I can’t be sure. The graphics chip may check for the electrical presence of the built-in LCD panel before it will output anything to the external monitor port. You might want to do some research on LM64P728 integrated controller used by this laptop for more information. Try to disconnect the LCD cable first and see if there is still output on the VGA port before removing the LCD entirely.

  • January 19, 2019 at 11:32 am

    Hi there! Good news, without the panel the laptop works AWESOME connected to my regular led monitor via VGA, so is like a portable 386 (I remove the battery too). I found another one online marked at 5 dollars (really) panel totally broken and DC-DC converter with a short, I can’t find the source but I change the working one with this one without any luck. I was wondering if there is any panel to use with original inverter, but I guess doesn’t make any sense since vga output is great. Thanks for your answer!!

  • January 19, 2019 at 1:25 pm

    Re-writing my wrong comment before. Hi there! Good news, without the panel the laptop works AWESOME connected to my regular led monitor via VGA, so is like a portable 386 (I remove the battery too). I found another one online 3/25 marked at 5 dollars (really), screen panel totally broken. DC-DC converter with a short, I can’t find the source but I changed it with a working one and works like a charm.

    Did anybody repaired a DC-DC converter? I changed the capacitors but nothing happened. The laptop turns on/off intermediately. I removed the HDD and everything on it including the screen.


  • ToughDev
    January 19, 2019 at 6:13 pm

    Great to hear that the laptop works without the LCD panel and with only external VGA monitor attached. Hope you will enjoy using it!

    As for the shorted DC-DC converter, try using a magnifying glass to see if you can identify the short visually. If you have replaced all the capacitors and it still doesn’t work, maybe the old electrolytic capacitors have leaked and shorted something on the board. One thing you can try is to wash the board carefully, clean it using compressed air, and let it dry for a few days before testing again. I have successfully revived a lot of vintage boards using this method.

  • January 21, 2019 at 5:32 am

    Thanks ToughDev!! I will give a try to that, I really want to repair the DC-DC just for hobby and have an spare in case the one working dies. Do you know any possible way to use the external VGA port with a capture device to record video? I try a few VGA to any adaptor with no luck, I was reading that some vga controllers need some electric circuits to properly display image in other kind of cables like RGB o HDMI. Do you know if maybe with a vga to composite + and avermedia or similar I will have a change to get direct capture? Thanks!!

  • ToughDev
    January 21, 2019 at 10:25 am

    You will need a VGA to composite converter, which has electronics to convert the signals, and not just an adapter. Most VGA to composite adapters rely on the controller outputting composite video on unused VGA pins and will only work with very specific graphics cards.

    This one from eBay (8 USD including shipping) will be able to work with the Contura

    Most USB TV tuners that support composite video should be able to capture the composite output from the converter – try this (5 USD including shipping)

    Let me know how it goes.

  • January 30, 2019 at 12:06 pm

    I’m back with news. Lets start with the caputre video combo suggested, worked, but not like a charm. You really need to play a bit with the EasierCap to get a regular/bad capture, but does the job. You can use OBS studio for best results since can record easily from most Chinese devices. I will upload a video talking about this laptop and mention of curse this site. Now in the other hand the DC-DC is pain in the ass, I need to identify some smd components, I dont know if they are caps or diodes or anything. Can I upload a photo with the unknown parts and see if anybody here can help me? My idea is to bring the broken spare dc-dc back, just to have another. I found that in ebay from Italy they have a few for 20 eur, just in case someone need one. Cheers!!

  • ToughDev
    January 30, 2019 at 2:26 pm

    Hi Nico,

    Great to hear your progress. Some cheap USB capture devices may be selective about their input signals and might need some tweaks to work with signals whose timings are slightly off. Typically symptoms include vertical rolling of the captured image or black and white video as the device might have difficulties locking with the vertical sync pulses as well as the PAL/NTSC color carrier. If there is an advanced menu in the capture software with various timing settings, tweaking those should result in better video output.

    Feel free to share the video and the photo of the unknown parts – I will see if I can find any useful information. When you share the link, try not to include http or www as the spam engines tend to mark such comments as spam. I will edit your comments to make the links clickable.

  • February 16, 2019 at 7:41 pm

    Hey there!! I did my best making a video with a few speaking errors. Sorry but is in Spanish (Im from Argentina) I added the thanks to you and the blog for all the help you bring me. I TRIED to revive the other Contura 3/25 but its seem that hangs all the time. I guess the mobo is almost dead, the computer works only for a few minutes, the good thing is I ended with 1 fully functional Contura 3/25 :) THANKS FOR EVERYTHING!!


  • ToughDev
    February 18, 2019 at 11:24 am

    Thanks for the video. It was well-done! I could understand the logic and the presentation even though I don’t speak Spanish. Love the games, especially Prince of Persia. Will follow your channel on Youtube and look forward to your upcoming videos!

  • March 9, 2019 at 1:28 pm


    Have Compaq Contura 4/25c (2820e) won’t turn on.

    When connect power, shows green light as charging battery but buttery dead.

    Can start up if keep it off for few days.

    Is it DC to DC convertor issue?

  • ToughDev
    March 9, 2019 at 5:01 pm

    I would suggest removing the battery and see if it turns on. The laptop doesn’t need battery to run. Mine works well without any battery connected.

  • March 9, 2019 at 7:50 pm

    Even without battery, same result.

  • ToughDev
    March 9, 2019 at 9:21 pm

    There might be an issue with the power supply unit which was caused by battery leakage causing the laptop to attempt to charge the battery even if no battery is connected. Check the connectors near the battery and see if there is any corrosion or leakage. If so, try to clean it. If you have a bench power supply, remove the battery and laptop power adapter, then set the bench supply to the battery voltage (printed on the battery) at around 2A, and apply it to the battery terminals (taking note of the polarity). If you are lucky the laptop should power on.

    Beyond this I am afraid you have to disassemble the laptop and troubleshoot the circuit. Very likely old electrolytic capacitors have dried up and will need replacement …

  • September 26, 2023 at 6:01 pm

    Stumbled by accident over this post, as i got a more or less working Contura 3/20 for cheap. Sadly the poor device got smashed up during shipping which damaged both screen and hdd beyond repair. VGA out is working like a charm and so far, appart from the screen and the hdd, only one of the caps on the DC-DC board seemed to have leaked a bit and the keyboard is a bit stiff.
    Gonna try and pop a compact flash card as HDD inside, if i can trick the bios, and run windows 95 on it. Maybe i can find another one for parts with a working display and keyboard.

  • ToughDev
    September 27, 2023 at 9:21 am

    Hi André,

    Thank you for sharing your experience. It’s sad to hear that the Contura suffered serious damages during shipping. I am not too concerned about the HDD because it would have to be swapped with a CompactFlash card anyway, but the LCD needs to be replaced (using external monitor is very inconvenient). You can try searching eBay or your local garage sales to find another non-working unit for spare parts.

    Windows 95 will be sluggish on this PC, with just a a 80386 processor and 4MB RAM, although I agree the Contura will look very cool with Windows 95 installed. The main challenge is that after the initial startup in MS-DOS mode and once Windows has entered protected mode, the Int 13h BIOS-extension (created by ANYDRIVE/EZ-DRIVE) will be lost, and any attempt to query the hard drive through the BIOS will return the temporary values that have been set in BIOS, and not the ones configured in ANYDRIVE/EZ-DRIVE. Absent any BIOS patching, you can potentially get it to work by setting the largest HDD size which is supported by this BIOS whose C/H/S values are smaller than or equal to the actual CHS values of the CF card (which can be found out by connecting the CF card to a modern computer). This way, you will not get to use the full capacity of the card but it might still work.

    Let me know if you manage to get it to work.

  • October 7, 2023 at 8:28 pm

    Hey guys,
    I have bought a 3/20 working till I took the HDD out to exchange it by a CF…
    Now, it just starts with the LCD flat cable disconnected and the floppy is not turning, just the head motor moves…
    When leaving the LCD connected the machine just blinks with a blip sound, the LCD shows some randome horizontal lines and everything switches off in a matter of 1 second.
    It feels to me like any voltage line is shorted. Have you been able to find the DC-DC converter output values? I would like to check what’s wrong since I know the LCD was working properly and the floppy also and that seems to be a short anywhere I just need to focuse a bit my search on.
    I love this laptop format, by the way, hope I can revive it.

  • ToughDev
    October 9, 2023 at 11:33 am


    There are usually 2 motors inside a floppy drive, a spindle motor that rotates the platter and an actuator/stepper motor which positions the head. Depending on the design, these 2 motors could be running from different voltage rails. For example, the spindle motor may runs from 12V whereas the stepper may run from 5V. If the 5V rail is alive but the 12V rail is dead, it could explain many of your observations.

    On some old drives, the spindle motor is connected to the rest of the mechanics via a rubber belt. If this belt has disintegrated, the motor could still be moving but the magnetic platter of the disk won’t spin. Can you check if this is the case? It seems weird that everything suddenly stops working after you connected the CF card. Newer motors use gears (and not rubber belt) and will not have this issue.

    A common source of shorts on the LCD panel is the inverter for the backlight mechanism. You can try to check there first – be careful of high voltages and of residual voltages on various capacitors.

    I hope you can revive that laptop. A full schematics could certainly be useful but unfortunately I have never been able to locate one.

  • October 9, 2023 at 7:51 pm

    Thanks a lot for your answer.
    I will check the floppy spindle mechanism, in case it uses a rubber belt, it actually makes sense.
    I did already disconnect the lamp from the inverter in case there was a short there, but it works indeed since, when disconnecting the lamp, the screen gets black (almost), so it should not be the lamp itself.
    I have not seen any electrolitic cap on that board, either.
    I may order the 4 or 5 we have on the main board, btw, since they may be licking and may have been barely working for a few hours before failing, i guess. Are there any other on the other side of the motherboard?.
    I have looked into the DC-DC converter with a IR camera and have seen a tiny kind of transistor terribly shiny, but it was not more than 40ºC or, at least, that’s what the camera said, and it may be coming from the other side of the board as well, by the way.
    Ok, as said, I will check the floppy mechanism and give you some feedback.

  • ToughDev
    October 10, 2023 at 10:06 am


    There were quite a few electrolytics capacitors on the other side of my motherboard, as far as I can remember. I replaced them as a precautionary measure, but my laptop worked fine even before the replacement.

    On the temperature measured by the IR camera, the values may or may not be accurate, depending on the sensor resolution and the software. Many cheap IR cameras have no way to adjust surface emissivity, a parameter critical for calculating temperatures from thermal images, and default to 0.95, resulting in inaccurate values. This has happened to me once when measuring the temperature of a transformer that had been coated with a special material. Try to see if your IR camera allows adjusting emissivity, or use a cheap infrared thermometer which allows setting this parameter.

    Beyond this, my golden rule for electronics circuit troubleshooting is checking voltage. Try to see if 5V, 12V and 3.3V are present. Connect the laptop to a bench power supply and observe the current consumption, with and without the LCD panel connected. Can you also check if the LCD cable is not damaged during the disassembly process?

    You can check out this repair video created by another reader as well as the videos and photos on the folder I shared in the article to see they can be of any further help.

  • October 10, 2023 at 10:48 pm

    Hi ToughDev,

    a little update from my situation. Wasn´t able to get it to boot anything past BIOS yet, as the floppy drive (canon MD3661) seems to have been also badly damaged in shipping. I opened it up and tried to fix it but sadly, the head had disintegrated in multiple areas and was broken beyond repair. A replacement drive is still possible to find even as new old stock for around 20-30 bucks – sadly for me shipping from USA to Germany is quiet expensive and doubles or even tripples the cost of the drive itself.
    However i managed to track down a unit in unknown condition for cheap, which apears to only has some cosmetic damage and some missing screws. Maybe i can salvage some parts (mainly the Display and Floppy Drive) from it, who knows. Will keep you updated!

    Also i found out that my unit came with an Memory Expansion Card, however i havent checked the size yet.

  • ToughDev
    October 14, 2023 at 9:02 am

    Hi André,

    Sorry to hear about the built in floppy drive. I agree that buying a new floppy drive may not be worth it, taking into account shipping costs and taxes. Let me know how it goes with the replacement unit. I hope you will be able to use the floppy drive from that unit, or salvage some other parts

    Additionally a PC floppy drive may be modified to work – I have previously tried with other similar laptops. It may take some time to figure out the pinout and to build a custom connector PCB, but it is certainly possible.

    The memory card from your unit is either 4MB or 8MB, most likely 8MB. The Contura 3/25C supports a maximum of 12MB of RAM (4MB built-in + 8MB external via the card). You can easily sell it on eBay for around $20-$30 and get back some of the costs, in case you can’t get the 3/25C back to fully working order.

  • October 18, 2023 at 11:59 pm

    Hey, me again.
    The parts-only machine arrived yesterday in a pretty rought shape – however i was able to safe the floppy drive and the screen from it and transfered it over to my unit no problem. While doing that i noticed a cap leaking on the inverter board – in fact, both machines had the same cap leaking on the inverter board. The parts-machine one has leaked all over the place and irreversible damaged the board and the components on it. However the one on my unit only leaked a bit so far and only damaged one trace. Will definitly swap that one out and clean the board.

    Appart from that the screen works fine but was very dark – turns out the “backlight” (if you can call it that, its just a little tube on the right side of the display) was broken. Swaped it with the one from the broken screen and low and behold, we can now see stuff.

    The floppy also works as it should.

    I found a forum post describing how to read the CHS-Values from the CF-Card/adapter installed in the device:
    With that help i managed to find values close to the ones the CF-Card/Adapter reports back (in my case Type 61 did the trick) and installed MS-DOS 6.22 and with that Windows 3.1 on it.

    I also tried installing Windows 95 from Floppy but so far had no luck. I tried two different images i found online, with the first returning an corrupted error after floppy disk 2, the second image reports errors while writing the floppy disks itself. Need to dig a bit into that later on.

    The additional memory installed is 4MB, which adds to the 2MB onboard my 3/20 has to a total of 6MB.

  • ToughDev
    October 22, 2023 at 9:18 pm

    Hi André,

    Congrats on getting the Contura to boot MS-DOS and Windows 3.1! Thanks for sharing the technical details on your repairs of the backlight. I hope that you will eventually be able to get the other unit back to working order, or at least boot using an external VGA monitor.

    Regarding your difficulty installing Windows 95 using floppy disks, I believe it is because your floppy drives (and perhaps the floppy disks which you are using) are only working marginally. If I remember correctly Windows 95 was distributed on DMF-formatted floppy disks. You can check if this is the case by verifying the floppy disk size – if it’s 1.68MB, then the disk is in DMF format. In order to achieve higher capacity, the DMF format has reduced error checking and data redundancies. This will work fine if both floppy drive and disk are in perfect condition but may not work reliably for old disks/drives. If you are determined to get it to work, try to clean and re-align the floppy drive, and use the original Windows 95 disks distributed by Microsoft (I bought mine from eBay), which were of much higher quality than third party disks. Otherwise, a more reliable way is to connect the CF card to a modern computer using a USB reader, extract the Windows 95 setup files from the CD version (using the ISO image) onto the card, connect it back to the Contura and run setup /is /iq

    You can read more about DMF here . Different Windows 95 releases can be downloaded here

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>