L40 sx problem - AGAIN (please don't kill me)

[sona1111]

well its me yet again, god apparently does not want anything about this project to be easy for me, so i return once more to bother all of you on these forums:

I have been running my L40 sx with taxing (but not impossible) power draw from the PS/2 port. There is the Pe3 xircom ethernet thing as well as the USB power (with a Ps/2 to usb converter) which powers the mini wifi bridge. I know it sounds like two devices on one PS/2 port might be bad, but it has worked correctly for over a month now. randomly, today i flicked the power switch on as i usually do and the light on the wifi flashed for a second and went out, after which the memory was checked and the system read out either a 301 or 305 error - i forgot which was the first, but i know i have seen them both after this problem. IT lets me continue to boot up but now no power comes from the PS/2 port anymore. Even if i take off a device. I think this is because a fuse inside of the machine blew.

I have had the same problem on another project and the fuses are usually marked with F(something) on the board. I found quite a few, but all that i could see read out a 0 resistance on the voltmeter, so i have no idea which one i should replace/bridge. Does anyone have a diagram of where the PS/2 fuse is, or know what i should do next?

 

[mbbrutman]

well its me yet again, god apparently does not want anything about this project to be easy for me, so i return once more to bother all of you on these forums:

I have been running my L40 sx with taxing (but not impossible) power draw from the PS/2 port. There is the Pe3 xircom ethernet thing as well as the USB power (with a Ps/2 to usb converter) which powers the mini wifi bridge. I know it sounds like two devices on one PS/2 port might be bad, but it has worked correctly for over a month now. randomly, today i flicked the power switch on as i usually do and the light on the wifi flashed for a second and went out, after which the memory was checked and the system read out either a 301 or 305 error - i forgot which was the first, but i know i have seen them both after this problem. IT lets me continue to boot up but now no power comes from the PS/2 port anymore. Even if i take off a device. I think this is because a fuse inside of the machine blew.

I have had the same problem on another project and the fuses are usually marked with F(something) on the board. I found quite a few, but all that i could see read out a 0 resistance on the voltmeter, so i have no idea which one i should replace/bridge. Does anyone have a diagram of where the PS/2 fuse is, or know what i should do next?

Sorry, but G-d has nothing to do with this. You misused something and damaged it.

Apparently it wasn't working correctly, or you were causing damage and did not realize it. That "PS/2" port is designed to operate a small keypad and a mouse, nothing more. The Xircom PE3 has it's own power adapter that you should have been using. I'm not sure what the power draw on the WIFI device is, but it is irrelevant now. Trying to draw power for both devices was just asking for trouble.

According to the service docs, a 301 is most likely to be a system board problem, but it could also be keyboard related. A 305 is most likely to be a keyboard error; a system board error or numeric keypad error is also possible.

If you are lucky it is just a fuse. There are chips used for signaling that you might have damaged instead, and that repair is going to be much more intensive, if you can find the parts. Your first task should be to find schematics, if they are available. Otherwise, you are going to have to look at the components and try to test them in place.

 

[sona1111]

ok, assuming the worst: that i cannot get the ps/2 port to work again, i have another idea to power my devices: the floppy drive.

It states clearly on its face that it uses 5v 0.8 A - enough for my uses. Because i hardly ever use it after installing the OS (to transfer files i use FTP), i could just remove it and wire the xircom PS/2 port to it - theoretically. What confuses me is that (like most laptop hardware), their is only the data connector, no power. But instead of having an extra few pins for power, it seems to have the exact same amount as a desktop floppy connector (data): 34! Does anyone know where this floppy gets its power from?

If this does not work i was thinking about wiring to the battery terminals, but they seemed lower then 5v, i guess because they do not detect anything to charge? If anyone can help me, i don't give up very easily.

 

[mbbrutman]

You certainly are persistent, but you are going to cause more damage. I would stop while you are ahead.

I also have an L40SX with a Xircom PE3. But I am perfectly ok with sitting down at a desk, plugging it into a wall, connecting Ethernet, plugging the Xircom in with it's own dedicated power supply. On a 20 year old laptop I'm happy that it works well, and trying to do unnatural things to it that might damage it seems counter-productive.

You need to keep the floppy drive and the controller intact; I wouldn't risk any more modifications.


Mike

 

[MikeS]

Pshaw! You wouldn't, but customizing and experimenting (and the attendant risks) are as much a part of the [vintage] computer hobby as restoring/preserving/collecting old hardware in pristine condition.

But first the OP has to find that fuse, if indeed that's all it is; they can indeed be well hidden...
I think 'jumpering' the fuse instead of replacing, or using the battery terminals, are definite no-nos though...

 

[mbbrutman]

I don't disagree with the fun in customizing and experimenting. But there has to be some caution exercised. Drawing a lot of power through a port not designed for it is just asking for trouble. Trying to make modifications without schematics or a good background in the hardware and electronics is also just asking for trouble.

 

[kishy]

Power and data are combined in the drive cable. It is possible to extract that power for use elsewhere, but I'm with Mike B on this - you're going to burn things (either in the 'magic smoke' sense, or the literal fire sense) that cannot easily (or at all) be replaced/repaired. You really should investigate external power supply options for additional features whose load exceeds what the machine can reliably be expected to supply.

I agree with Mike S also - mods are cool...but some limitations really need to be respected.

 

[MikeS]

Power and data are combined in the drive cable. It is possible to extract that power for use elsewhere, but I'm with Mike B on this - you're going to burn things (either in the 'magic smoke' sense, or the literal fire sense) that cannot easily (or at all) be replaced/repaired. You really should investigate external power supply options for additional features whose load exceeds what the machine can reliably be expected to supply.

I agree with Mike S also - mods are cool...but some limitations really need to be respected.

I sort of agree with both of you, but I doubt that you (or any of us) know what the actual current demands and reliable supply really are.

It's one thing to advise caution and warn against possibly unforeseen consequences, but quite another to say to someone, without knowing the technical details or his/her knowledge and expertise, that he/she is "going to cause more damage", "needs to keep the floppy drive and the controller intact", is "going to burn things" and "really needs to respect certain limitations (whatever they really are)".

If the OP knows the risks and is willing to take them instead of *assuming* that it probably won't work, more power to him! That's the spirit that created most great inventions but is being stifled more and more with today's follow-the-consensus approach to science and much of life in general, and there's way too much totally unfounded "it won't work because..." stuff on here and the internet in general anyway.

If he does blow it up, so what? His business, not ours (but he still has to find that fuse first ;-) which is why he posted in the first place)

 

[Unknown_K]

If there isn't a fuse for the PS/2 port there might be a circuit board trace that melted, look for discoloration between the PS/2 port and the keyboard controller chip.

 

[mbbrutman]

I sort of agree with both of you, but I doubt that you (or any of us) know what the actual current demands and reliable supply really are.

Apparently the current demands were too great for the PS/2 port, which is now damaged in some way. And it defies common sense to try to power two external devices, one of which has the provision for its own external power source, from a PS/2 port. This accident could have been avoided.

It's one thing to advise caution and warn against possibly unforeseen consequences, but quite another to say to someone, without knowing the technical details or his/her knowledge and expertise, that he/she is "going to cause more damage", "needs to keep the floppy drive and the controller intact", is "going to burn things" and "really needs to respect certain limitations (whatever they really are)".

Well given what has happened already, one can pretty easily infer the level of expertise here. And risking damage to the floppy controller by modifying it to draw power for the same devices that damaged the PS/2 port seems a bit foolish, especially since finding a replacement floppy controller for this machine (or repairing damaged ICs) will be very difficult.

If the OP knows the risks and is willing to take them instead of *assuming* that it probably won't work, more power to him! That's the spirit that created most great inventions but is being stifled more and more with today's follow-the-consensus approach to science and much of life in general, and there's way too much totally unfounded "it won't work because..." stuff on here and the internet in general anyway.

If he does blow it up, so what? His business, not ours (but he still has to find that fuse first ;-) which is why he posted in the first place)

You are right - it's none of our business. But sometimes people don't know what they don't know, and reminding them that they can cause further damage is a noble thing. Especially since we're not exactly finding a cure for cancer here - it's not a noble endeavor that the world can't live without.

As a matter of personal policy I don't help people fire up a chainsaw after I see they are bleeding from an encounter with the hedge trimmer.

 

[sona1111]

wow lots of posts while i was gone...

For those who care: this project has been ongoing for a couple of years now, the purpose being to get a old l40 sx laptop In complete modern internet cafe-type working condition. Obviously i have plenty of other computers i can use for the task, (and much faster ones, at that) its just in the spirit of fun to try and get what might seem impossible on this ancient hardware working as described. (and then, of course, bringing it into said internet cafe

I was amazed at the level of help i received when i cane to these forums, i started with a computer that could only boot from a floppy and run programs from it with no communication at all, and, over a LONG amount of time, (for me, that is) I slowly improved the machine. (but also had many blunders, like the broken keyboard, and this ps/2 problem. I was very surprised when i came across the correct combination of hardware to technically do what i want. (xircom + wifi bridge) BUt i had problems, first with the impossible configuration on the first, then the slightly more possible but still unworkable (ajax) problem with the second, and now this.

I am, no matter how stupid it might sound, determined to see it through till the bitter end! And hey, if i end up figuring it out after brreaking a few things, i can always keep my eye out until i see one on ebay and carry out said found solution on it!

So again, Any information available for supplying the needed power for these two units would be gladly accepted.

 

[mbbrutman]

Sona,

I should probably chill out a little - I'm probably coming across as harsh. I know how hard it is to fix things after the magic smoke gets out, hence the reaction.

I think a really good first step before doing anything else is to try to find schematics for the L40SX. I don't know if IBM published them in a technical reference or not; they did on the older machines. I haven't seen them for the L40SX, and I've been looking.

I'd be really careful with the floppy drive - any replacement parts are probably going to come from junker machines. You don't want yours being turned into the next junker because of another accident.


Mike

 

[MikeS]

Apparently the current demands were too great for the PS/2 port, which is now damaged in some way. And it defies common sense to try to power two external devices, one of which has the provision for its own external power source, from a PS/2 port. This accident could have been avoided.

Accident, or learning experience like Edison's? Since presumably the goal is to make the unit self-contained and running on battery I think it makes perfect sense to try to steal the power from the main unit somehow instead of using a wall-wart. I'm actually surprised that the PS/2's current limit was exceeded since it was in fact often used to supply power to accessories in addition to a keyboard and mouse, and I probably would have tried the same thing myself.

You are right - it's none of our business. But sometimes people don't know what they don't know, and reminding them that they can cause further damage is a noble thing. Especially since we're not exactly finding a cure for cancer here - it's not a noble endeavor that the world can't live without.

Like I said, I agree in principle; my issue, as it is with many of my other rants, is with the out-of-hand rejection of his idea without any real facts or figures, and the tone, judging as in "You *will* break it" instead of advising that "you might" and "you *need* to" instead of "*maybe* you should..." and maybe even helping him (at his own risk of course) if possible.

Don Quixote tilting at windmills...

 

[mbbrutman]

And a minimum amount of prudence would suggest knowing the current requirements of the devices you are attaching and the limits of where you are pulling it from. Or in the case of modifying hardware, being able to refer to schematics (and verifying them because they are often wrong!), or being able to reverse engineer the design.

Life is full of calculated risks. In this case, the Xircom adapter power supply provides 300ma at 12 VDC. One can safely assume that is the upper end for what it would require. (The PS/2 port only provides up to 5VDC, so there we have an factor that I would lump in the "unknown" category.) I'm willing to bet that a Wifi bridge, given it's requirement to transmit, is going to require more power, and I would look at it to figure it out. But that's just me being prudent.

No "real facts of figures" ? We know the PS/2 port has been damaged already, and we know that nobody has computed the power budget or obtained schematics, hence the questions about how to tap from the floppy connector. I think the facts that we know and the history so far call for stronger cautions, not weaker ones.

 

[sona1111]

Yes the idea was to have the unit self contained, hence external power supplies are not an option, however i have another idea: IT it possible to get the required power from "AA" sized batteries that are being used in the repaired battery pack? Their are nine batteries in series, each at 1.5 V, used to power the unit, maybe i could connect a lead somewhere along the string of batteries that would provide 5v and enough MA for both devices..thoughts?

 

[MikeS]

...I think the facts that we know and the history so far call for stronger cautions, not weaker ones.

We're on the same side; I'm just sayin' that there's a difference between urging caution and saying, "You don't know what you're doing, so don't do it!"

To the question of 'tapping' the battery pack at 5 (4.8?)V: assuming the ground is common it'd presumably work, but if they're rechargeable cells it's not a good idea; when you recharge them, some will be much more discharged than others and thus either some will be overcharged or some will be undercharged, and some may even be reverse-charged.

Can't you just nicely tape a 4-cell AA or AAA battery holder to the Xircom? That'd avoid all the risks involved and also not take away from the main battery run time.

But I'm puzzled: if the Xircom adapter puts out 12V as MB says, how are you connecting to the PS/2 5V supply?

 

[mbbrutman]

But I'm puzzled: if the Xircom adapter puts out 12V as MB says, how are you connecting to the PS/2 5V supply?

It's an original adapter that I'm looking at. I suspect the Xircom runs fine on 5v .. it has to. But the circuitry inside it might be able to use more write current when transmitting, improving the link quality when 12v is supplied.

 

[MikeS]

It's an original adapter that I'm looking at. I suspect the Xircom runs fine on 5v .. it has to. But the circuitry inside it might be able to use more write current when transmitting, improving the link quality when 12v is supplied.

Certainly possible; maybe that's why it's so high, 12V when 9V would be adequate and waste less power if you're only using 5V.

But in any case, if the external supply is 12V there's presumably a regulator somewhere to drop the voltage down to 5V; if we're doing serious hacking anyway, bypassing it and any resistors, chokes, etc. in the path *might* reduce the current draw somewhat (if he's not already doing that).

But my suggestion's still to inconspicuously stick a small battery holder on to the Xircom or bridge and use that to power them.

 

[carlsson]

I don't know if it adds anything to this discussion, but I have a Xircom PE3 which I have powered both from a 5VDC 2.5A and a 12VDC 1A external adapter. For a while, I got the feeling it ran better on the 12V but that probably was just a coincidence. One should look inside or try to find a schematic to determine what the ideal voltage is, as I suppose there is a regulator.

 

[sona1111]

so heres the current situation, i had been looking on ebay a while for a replacement l40 because the keyboard was broken. (rather, the physical connectors were broken, but the keyboard itself was fine.) I came across what i thought to be the best deal going i had seen for a while, for five dollars, i got a l40 with just the mainboard, case, screen, and keyboard. inside there were no drives or memory or cables at all, just the mainboard.

so i went ahead and got it.

After attaching my my screen and floppy drive and backup battery to it, i flicked on the power and there was still some life in it. I got the expected 161 and 163 errors, as well as one i had not seen before, 601 Also, it dumps me to basic because the floppy will not run. Any ideas?