Help needed with kicking IBM L40SX back to life

[jpvloeimans]

Hi everyone,

I have a IBM L40SX which worked when I got it, but after some strange behaviour seemed to have died down. I'd like to get it back to life, but I don't know how. Does someone have an idea what to do?

I recently picked up a rather neglected L40SX from someone who was cleaning out his attic. The outside of the machine was quite dirty, but I suspected the inside of the machine would be a lot worse, because the back of the machine showed some signs of battery leakage. When I picked the machine up from the previous owner, he already had it running to show to me it was working. But once I got it home, I hesitated to turn it on without knowing how the internals looked like.

So, with the help of an online tutorial from a fellow L40SX-owner, I managed to safely disassemble the entire machine. And it was a mess! Amazingly and luckily, none of the circuitry was stained by the battery leakage and I managed to clean the entire plastic casing. After completely assembling the machine, it looked brand new. What a difference!

Inside, I saw that no extra RAM was fitted to the mother board, there was no Math Coprocessor present, and an internal modem was installed.

Now, I dared to give it a try and fire it up. I double-checked with the original reference guide that the machine could safely run without the main battery installed and hooked everything up. The moment of truth: I switched the power button on, all the LCD-indicators and the screen briefly lit up, and the 2MB of RAM were counted. It worked! I needed to run the reference disk to get rid of the 161 and 163 POST-errors and it booted smoothly into DOS 6.22 which is installed on its HD. It turned out it has also Windows 3.11 installed, so I fired it up as well and it worked like a charm.

But not all was well:
- A few times, the keyboard stopped responding and I had no choice but to flip the power switch off and on. I couldn't change the Num and Capslock indicators either. There was no sign of any activity. After a reboot, it worked well again, but after a random amount of time it stopped working again.
- One vertical line on the screen remained black, from the bottom of the screen to halfway up. But after some time, it magically worked again.
- The previous owner indicated that the HD sometimes failed, but I didn't notice that in the short period of time I used this machine.

Sadly, during my last reboot, the L40SX stopped responding to the flip of the power switch. The screen remains black, the HD and the floppy drive remain silent, and the LCD-indicators do not lit up. Only the battery LCD-indicator shows that the machine is connected to the AC-adaptor, so it has power. As nothing is booting up, I get no error codes or other clues on what might be wrong. It could be a faulty power supply, a faulty power switch, or that I have not fitted one of the connectors properly. Or maybe the HD broke down?

I stripped down the machine once again, and assembled it step-by-step, making sure everything is hooked up properly and to ensure that nothing is broken, at least visually. But it didn't change a thing. After letting the machine rest overnight, I tried to fire it up once again, but with the same result: nothing.

I already scanned this forum, but I couldn't find any hint or solution. What troubles me is that the L40SX does not power up at all and it doesn't start the POST. A faulty HD doesn't prevent a computer from trying to boot, right? So, I need help with getting it back to life and decided to post my question on this forum. Does anyone have a clue what could be the problem or how to solve it?

Kind regards,
Jeroen (The Netherlands)

 

[jpvloeimans]

Success! It turned out to be a faulty cable which connects the power switch and the LCD-indicators to the mother board. The cable is not completely broken, but it is slightly damaged at one point causing it to disconnect when bent in a certain way. When that happens, the power is cut off immediately and the laptop appears dead.

Now that I know what causes this problem, I was able to temporary fix it with a bit of tape... I'm going to look into a way to fix it nicely and permanently, but for now, it works.

I noticed the little CMOS-battery is dead as well, so I need to replace it. It's not as simple as the battery in a ps/2 model 70, for example, but a bit of soldering should do the trick.

If anyone has similar trouble with his L40SX in the future, feel free to PM me or to reply to this thread.

Kind regards,
Jeroen

 

[IbmMarco]

Hello, Jeroen:
I own the same machine you have since one month or so. It came with modem card, 2mb ram and 60mb hd. The portable battery was big than usual and also seemed in bad shape so I didnt use it. It came without charging power station so I bought one with several conectors to fit in the laptop (15V one).
With all this I started the machine and two errors came: battery bios. I changed the battery bios with one from a photo camera (3V one) and it worked fine. I remove the fax-modem card as I dont have any use for it. The hd has a w98 so but after the w98 screen it came to dos system. I worked five or seven times with this and then suddenly didnt work. I remove it and now I work with 3.5 1.44mb diskettes.
Recently, I experience the same problems that you seem to have: screen in and out, keyboard not responding... but they dissapear as soon as started after one hour or so of rebooting and rebooting... also I changed the place of the laptob: I normally use it in a flat table but this time that I experience failures I have taken it to a irregular and soft chair... Could be that the problem, an overheating maybe?
All of this history is to say: wich cable do you mean? In manual instruccions there are named. Or if you could upload a photo, in order a could check if that would be a problem in future (it seems it will). I would be grateful, thank you very much.
Also I am willing to do this:
-Install an cf-ide adaptor to run a cf 1gb card as hd.
-Install an internal audio jack 3.5mm female with volume so I could use headphones or take the sound to a monitor (the vga port only show image as you now).
-Instal a lift-battery so I have easy access if I have to remove again the battery bios.
-Remove the disquette and replace by a gotek usb one.
-Remove the lcd monochrome screen by a colour one.
But I dont know if all of this can be done and how to do it. If you or anyone can help me about I would be very happy and of course share my steps (failure or not) in that matter.
Thank you very much!! Regards.
Marco.

 

[jpvloeimans]

Hi Marco,

Could be that the problem, an overheating maybe?

This could be a problem, because this machine is not equipped with a fan. Also, this machine contains a humidity sensor which cuts the power when the environment is too humid.

All of this history is to say: wich cable do you mean? In manual instruccions there are named. Or if you could upload a photo, in order a could check if that would be a problem in future (it seems it will). I would be grateful, thank you very much.

I've had no time to disassemble the laptop for photographing the internals, but you can visit this page (http://www.brutman.com/L40SX_DOM/L40SX_DOM_Upgrade.html) and see the two pictures of the top shelf ribbon cables. The small one is for power, the big one drives the lcd-indicators. The pictures show how the cables connect to the motherboard. The other ends (not shown on these pictures) connect to the top shelf. These flat cables are very fragile and can easily be damaged by uncarefully (dis)assembling the laptop or (dis)connecting the cables. Even the slightest bit of damage can cause it to show weird behaviour or just to malfunction. Repairing the cable seems almost impossible to me, so replacing it with a spare is your best option.

For all the upgrades you wish to plan, I wouldn't know if they would be possible. Upgrading to an SSD has been done before, see the link I provided above, but things like installing an internal audio jack or replacing the screen by a color one is impossible. By my knowledge, a color screen for this particular model simply does not exist. Also, this laptop is so tightly assembled, that I wouldn't know how to fit extra stuff in it.

My suggestion is that you should at least try to repair it to a normal working order state, before trying any fancy updates.

Good luck! Cheers, Jeroen

 

[josedelcour]

Anyone has the service manuals for the IBM L40 ? Mine just stopped working and, when turning it on, the lights behave completely erratically, with the main screen lit up, but nothing happens. Just before that, the memory counted up to 640K and was stuck at that level.