Thinkpads Forum

Hi. I recently got a Thinkpad 750 (maybe c, but I can't power it on to tell) at a yard sale ($1, woohoo!). I'm pretty sure it will work, since it's really durable and airtight and everything. Anyway, I need a power adapter to make it work. I can't find one that says it's for the 750, but I've found ones for the 700 series and thought they might work. The plug looks like the one here, https://www.savingology.com/IBM-49G2196 ... 9g2196.htm but I'm not sure if the voltage is different or anything. Also, there's another one that's an official IBM one here, https://www.savingology.com/22P9010-AC- ... 2p9010.htm but I can't see the plug end. It says it's for the 770. Would either one work? Thanks.

the first one should work on the 700 series..
700 being from 700 through 750 at least and maybe the 760 series..

what you have, if it works, is an antique..

you'll need to pull the battery and make sure it is not leaking..
those were NiCad batteries..
finding one that will work will be a problem..

if you want to invest the $$ in the AC adapter, give it a try and see if it boots up..

also, the CMOS battery will be dead.. you'll need to use the Esc key to bypass the CMOS error warnings.. (date, time and so forth)

i probably have one or two of those in my hardware archives..
original IBM not aftermarket versions..
this is not an offer to sell one but let me know if they want more than $10..

welcome to the forum..

Welcome to thinkpads.com!

The first link appears to show a generic AC adapter for the 750x series. The Hardware Maintenance Manual for the 750 series lists 49G2196 as a 40W adapter and in the power checkout section it says that the power supply should output 20V. Your referenced listing says 16V in a couple of places. Were it me, I would NOT get that one. Currently on eBay there are these two:

http://www.ebay.com/itm/231603468616
http://www.ebay.com/itm/191613437315

These show what seem to be actual IBM adapters (at least from the photos).

Your second link is NOT for the 750 series as it is the common 16V adapter that has a yellow "barrel" DC plug, not the 4-pin that's on the 750.

Thanks for that eBay link! Not only is it cheaper, but it's official IBM.

The battery's not leaking. It probably would be hard to find a 20 year old battery that still carried a charge, but I was never going to try. If I can get it to work at all I'll be happy (and it will probably be easier to get it to work knowing how to bypass the dead CMOS battery warning. Thanks for that. I'll let you guys know what happens!

Weboh wrote:The battery's not leaking. It probably would be hard to find a 20 year old battery that still carried a charge, ...

Keep in mind the design of the charging system of the 750's battery. It's like a Christmas light string. The system may not power up with the dead battery installed. The 750 battery is a "smart" unit with a little logic board and programming that gets lost once the battery dies. The battery can no longer be charged using any conventional method. Also of note, there is a ban in place for the import of the "cells", so any company still offering refill service may be a dead end if they ship the battery to China to get the cells replaced.

Way to be a Debbie Downer.

I guess I can't take out the battery to ensure it doesn't leak and lighten the weight then. I guess I'll have to hope it can "carry" a charge through it even if it can't hold it after being unplugged. You said it <i>may</i> not work. Did some batteries have logic boards that didn't need a charge to hold the memory? It has a conventional hard drive that doesn't need a current to keep alive.

Weboh wrote:Way to be a Debbie Downer.

I guess I can't take out the battery to ensure it doesn't leak and lighten the weight then. I guess I'll have to hope it can "carry" a charge through it even if it can't hold it after being unplugged. You said it <i>may</i> not work. Did some batteries have logic boards that didn't need a charge to hold the memory? It has a conventional hard drive that doesn't need a current to keep alive.

I'm sorry, I wasn't clear. The system may not power on with the battery installed. Please remove it to use the system. You will need to use the system plugged in only.

The old 750 smart battery logic board used the charge of the battery itself to maintain the program in memory. Once the battery died, the program is lost. The 360 battery was a dumb version of the 750, but still has a cut off switch to stop the battery from charging once it got below a set point.

So the laptop powers on, but the only thing it gets to is a screen that says "0800 KB OK" and has a flashing DOS-style cursor beneath it, but I can't type anything. What causes this message? Does the OS need to be reinstalled or something? I should probably mention The hard drive hard drive light and what I assume is the power light (the one on the far right) are the only lights on. And I can hear the hard drive spinning, but it doesn't sound like kind I'm used to--it's more like a slide whistle going in and out, pausing for a bit and then starting again.

Weboh wrote:So the laptop powers on, but the only thing it gets to is a screen that says "0800 KB OK" and has a flashing DOS-style cursor beneath it, but I can't type anything. What causes this message? Does the OS need to be reinstalled or something?

Off the top of my head and without seeing it, it sounds like it's not finishing the memory test. How long do you let it sit like that?

I'll see if I can locate a diagnostics / service manual with error codes. I think I have one.

I let it sit for about 5 minutes before posting. Should I let it sit longer, or could that hurt it? I first tried it without the battery, and now I'm trying it with the battery and getting the same screen. (so maybe the battery can still carry a charge? There was a power switch on the actual battery that was switched off)

Edit: Now the hard drive is making a continuous loud whine. That can't be good, right?

Weboh wrote:I let it sit for about 5 minutes before posting. I first tried it without the battery, and now I'm trying it with the battery and getting the same screen. (so maybe the battery can still carry a charge? There was a power switch on the actual battery that was switched off)

The battery is 20+ years old. Not likely to be doing anything. The off switch was used when storing the battery unused for a period of time, maybe a year or two.

Unplug it.
remove the
floppy drive,
hard drive,
battery,
memory card ( The memory card (if any) is under the floppy drive)

WITHOUT plugging it in, move the power switch to the on position a few times (hold a couple of seconds) to make sure there is no charge still in the circuitry.

Plug in

Turn on and see if anything has changed.

If it finishes the memory test and goes into the graphical setup screen, there are diagnostics you can run.

You can then turn it back off and add one item back into the configuration at a time, testing each time to see if anything changes.

Question: on the bottom of the screen, does it say 750 or 750C or 750 Cs?

Hard drive noise may not be good.

There was a memory card under the floppy drive, and I removed it and everything else. Got the same message.

It says 750.

Weboh wrote:There was a memory card under the floppy drive, and I removed it and everything else. Got the same message.

It says 750.

I'll see if I can find the manual I wrote about.

It sounds like it a monochrome unit.
The model number on the bottom of the case would tell for sure.

fultontech wrote: It sounds like it a monochrome unit.
The model number on the bottom of the case would tell for sure.

Type 9545-006? (C) 1993

Weboh wrote:

fultontech wrote: It sounds like it a monochrome unit.
The model number on the bottom of the case would tell for sure.

Type 9545-006? (C) 1993

Yup. That's the monochrome unit that came with the 170MB drive. $3199 brand new in 1993.

It just says "0800 KB OK" ? There are no beeps or anything?

What happens if you turn it off, then press and hold the F1 key while turning it on?

Now it says 03904 KB OK.
I'm assuming that's because I took out the memory card.

Weboh wrote:Now it says 03904 KB OK.
I'm assuming that's because I took out the memory card.

Yes. That means the memory on the system board is ok.

It may just be that the memory card needed to be taken out and put back in, or that the card is bad and you need a new one.

Try it with the card in again.

Now it says 8000 KB okay again.

I actually do have another one of these computers to replace any part that might be bad.

Weboh wrote:Now it says 8000 KB okay again.

I actually do have another one of these computers to replace any part that might be bad.

Wait, you wrote 0800 at first. is it 0800 or 8000KB?

It might have been 8000 at first, but it definitely is now.

Weboh wrote:It might have been 8000 at first, but it definitely is now.

That's a 4MB card.

Press and hold the F1 key; then power-on the computer. Hold the F1 key down until Easy-Setup screen appears

Nothing happens when I do that. I tried it with and without the memory card, since I found an old online manual for similar computers that said to take it out before running the test. I'm not sure what's wrong though.

Weboh wrote:Nothing happens when I do that. I tried it with and without the memory card, since I found an old online manual for similar computers that said to take it out before running the test. I'm not sure what's wrong though.

The service guide says;

No Beep Symptoms

Symptom/Error:
No beep, power-on indicator on, and a blinking cursor only during POST.

FRU/Action:
1. System Board
2. Processor Card (370C, 750Ce, 755C, and 755Cs)
3. DC/DC Card

Basically it's the computer.

Nooo... How hard would it be to take the guts out of another Thinkpad 750 and put them in this one? (The other one's screen is shot. Or, would that one work with a VGA screen without having to go through a setup on its screen?)

Weboh wrote:Nooo... How hard would it be to take the guts out of another Thinkpad 750 and put them in this one? (The other one's screen is shot. Or, would that one work with a VGA screen without having to go through a setup on its screen?)

I've done it before, but I've worked on IBM stuff since the late 80's. I always have trouble with the screen ribbon cables and putting the keyboard back in.

I've got a few 750's as part supplies now.

You need the service manual:

http://download.lenovo.com/ibmdl/pub/pc ... tpvol2.pdf

The other one gets past the first part, beeps twice, and gives me a error that says 19990303 = Not OK and then an arrow pointing to an IBM manual.

Thanks for all the help troubleshooting by the way.

Weboh wrote:The other one gets past the first part, beeps twice, and gives me a error that says 19990303 = Not OK and then an arrow pointing to an IBM manual.

Thanks for all the help troubleshooting by the way.

Not a problem. 199XX is the System Board

So the system board is bad with that computer? What exactly is wrong with the other one? Not the system board?

Weboh wrote:So the system board is bad with that computer? What exactly is wrong with the other one? Not the system board?

The "new" one we were working on? The manual gave a list that included the system board, but wasn't specific.