Boot-Up & (CMOS) Problem with "Old" Compaq SLT/286

I have just recently got hold of an old Compaq SLT/286 "Laptop" PC. Massive big thing, like a brick. I believe it was the first Compaq laptop ever? Anyway, that's not the point.

I have two problems: The first one, I connect the battery and the power adapter and flick the on button on the left-hand side. The power light on the front glows, and the lights on the detachable keyboard(num, caps & scroll) flash for a moment. Then all activity stops, have left it on for hours and nothing changes.

PROBLEM TWO: I sometimes manage to get the screen to come on and things start to boot. This is a rare opportunity, so I tried to reinstall everything. When I got one of these rare opportunities I got the error message: "Systems Options are not set. Run Diagnostic Disk Resume F1 Key." I ran the floppy Diagnostic Disk, and went to save the changes and restart the computer. Upon restart, the same message appeared. It just kept on appearing. So I put in the OS install disk (MS-DOS 6.22 i think) and ran that. It all worked, Initialized the PC and formatted the 40mb HDD and installed the software. It then wanted to restart. I did this and the same error message came up. It just wont go away and wont let me boot the OS.

I'm really fed up now because I turned it off again and then it wouldn't start, so back to problem 1.

SO: A) How do I fix problem 1? and B) How do I fix problem 2?

Please help, I'm so desperate for this classic Laptop PC to work! Thanks very much in advance . . .

I'm not sure about Problem 1, someone with more knowledge than me will have to help there. But in Problem 2, its asking for a disk that set the information about it. Like how much RAM, HD type etc. I have some Compaq Setup disks, but I don't know if they would work on a SLT/286 or not. What kind of floppy drive is it? 5.25 or 3.5?

the problem you have is that you have the infamous Dallas real time clock & cmos chip (brick!), can't remember what the number is off the top of my head, but it needs replacing or the battery digging out of the top of the chip / the battery connections digging out of the side of the chip and the battery replacing with a 3V lithium cell, in order to hold the setups (do a google to find out how).

Quite a few pcs just don't boot if they have a corrupt setup.

Apparently the chip is still available or you could put the batteryless version on the board and wire a battery to the two legs (check they aren't connected to ground on the board - or bend them out) if you want the thing to work in 5 years time

I had no luck with the cannibalism option - so I might have to do some shopping

I have even earlier Compaq "Luggables". In my case, as long as I leave the machine ON after running setup, I'm OK. Turn it off and it's time to run the setup again. It will boot but doesn't "see" the hard drive until I once again tell it that it's a Type 2 disk. Voila, will boot off hard drive until you forget and flick that switch.

Second the motion on the dead RTC chip. That would be my first guess too.

--T

nige the hippy said:

the problem you have is that you have the infamous Dallas real time clock & cmos chip (brick!), can't remember what the number is off the top of my head, but it needs replacing

Click to expand...

It is, most likely, a DS1287.

The replacement for it is the DS12887 and they can be purchased at www.futurlec.com (that's where I got mine for some ridiculously low price).

I believe they even have the DS1287s, but, I don't know how much life they'd have left in them after all this time unless they were stored in liquid nitrogen.

Look around for a 24 pin (some of the pins will be missing, but, that's ok, they aren't SUPPOSED to be there) black block and see what the part number is on it. With any luck, it'll be socketted and you won't have to unsolder it to put a new one in.

THANKS VERY MUCH!
Just to confirm problem 1:
Nige the hippy: "Quite a few pcs just don't boot if they have a corrupt setup."
Is the quote above true for Compaq SLT/286? Remember it does sometimes boot-up half way before coming up with the error message, then it wont do it again for another day, then it will half boot etc.
Are problems 1+2 linked? Or is there a seperate issue with something on problem 1? Look back at my first post for more info.
TO HELP YOU: When the screen stays blank I get no bios beeps atall. Just the power led & the keyboard lights flash. However when i do get some life from the screen, along with the error message I get two short bios bleeps. I believe this just ties in with the system settings are not set?
Problem 1 linked with Problem 2? HELP ME OUT ONE LAST TIME PLEASE!

You never know if it is the CMOS setup that stops the boot altogether or not until you have replaced the CMOS, then if the problem persists... you have another problem and hopefully you replaced the soldered-in CMOS module with a socket and haven't wasted it!
all I can say is that corrupt cmos can cause all sorts of fairly terminal-looking problems, swap it & you're probably laughing.

and - unfortunately it is soldered in - replace it in a socket & put hot-melt glue on it to hold it in place.

remove the chip - extreme care or you'll damage the board, use solder wick or a good sucker, and pay extra care to holes that prove awkward to clear, you might need to add extra solder and re-do it a few times, there are sometimes ground and power planes that suck the heat away - then buy a chip and a 24 pin socket, solder the socket in, and then put the new chip in it.

Thanks very much for everyones posts.
I am now going to buy the Dallas RTC & the 24-pin socket.

I shall chop off the legs of the existing chip. Then I will simply melt the solder & pull out the remaing parts of the legs. After this I will solder in the socket, and then plug in the RTC. Simple, I just hope that this solves all the problems! I just have a funny feeling it may not . . .

However, I am on holiday now until 26th August, but will post the result of my project before the end of the month.

Until then, thank you very much. And PLEASE DO CHECK THE POST at the end of the month because there may be some more problems!

If it makes you feel any better, on a Mac, when the PRAM (read: CMOS on a PC) battery goes below a critical point, the pretty lights all come on but you get NADA in the way of screen, drives etc., so, you might be getting the dying gasps of the DS1287 when you're trying to boot. Sometimes it's just over that critical point and sometimes it's not.

Druid6900 said:

If it makes you feel any better, on a Mac, when the PRAM (read: CMOS on a PC) battery goes below a critical point, the pretty lights all come on but you get NADA in the way of screen, drives etc., so, you might be getting the dying gasps of the DS1287 when you're trying to boot. Sometimes it's just over that critical point and sometimes it's not.

Click to expand...

Thanks very much, I do feel a lot better now! I've ordered everything now to replace the CMOS, so lets just hope that it fixes everything!

Unfortunately, my old CMOS seems to have now gone beyond the point of no return, and has stayed in its pretty lights but nothing else stage for two days now! Still, never mind, looking forward to coming back from holiday and fixing my classic PC.

Will post again with result before end of the month. However, as I don't go on holiday for another two days, keep on posting with any new ideas that pop into your head(s). Although I hope I've got everything I need to restore my laptop now!

Sorry for not posting before the end of the month as I had promised, but things got a bit hectic when I came back from hols . . .

Anyway, the mystery continues as I can't get the component de-soldered off the board. I did my best, used solder wick etc. but it just wouldn't come.

About ten minutes ago I rang some very nice bloke in a nearby town who does pc repairs and managed to persuade him to come and look at it. He should be here in an hour or so.

So fingers crossed he'll do it for me, and fairly cheap too!

I PROMISE TO POST ONE LAST TIME WITH THE FINAL RESULT:
EITHER, HURRAY! IT WORKED. OR HE WOULDN'T FIX IT FOR ME & I'M ON MY WAY TO THE TIP RIGHT NOW. . .

Will post again soon . . .

When I had an SLT with just glowing lights that wouldn't boot, I found it was the main battery pack that was dead, not the RTC. Even after the RTC's been replaced you may have to remove the main batteries and run it from the AC adaptor.

Oh, what a saga! The bloke said he wouldn't do it for me. I am back at work now so I just don't have time to sort it out until the middle of October.

Thanks so much for everyones posts. I think I'd better leave it here!

Shameless Plug follows.....

Send it to T, he'll get it going for you. He knows all about those old laptops and even rebuilds battery packs.

He even still has all his fingers, so, he's pretty good with a soldering pencil

Right, T?

Gee...flattery...???

--T

One problem guys. I live in the UK. Thanks for your help though.

this reminds me of the day i had this old tandy laptop (i'd remember the model, but the jerk who had no clue how to fix it threw it away!) although it was the battery that went dead, not the cmos. I miss that Tandy.

Hi,

I'm new to all this but am trying to get an SLT286 to work. It lacks a Diagnostics disk and I'm getting the usual 162 error code message.The main battery has some charge and I've tried it with and without that battery. Could anyone supply me with a copy of the Diagnostics disk- happy to pay for time and postage. Am based in France but return to the UK fairly often.

Grateful for any help.