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IBM 5140 Won't power on, best and worst day ever.

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pcm2a

Experienced Member
Joined
Jun 24, 2013
Messages
190
I picked up this 5140 the other day and man is it one awesome old machine. I was bummed that it didn't have the adapter for the parallel/serial. Today I picked up the IBM bag and in the front pocket was the adapter! I got my Xircom and mTCP files onto a floppy, plugged the adapter in, powered the pc on and it came on for about 1 second then turned off. Now it won't power on at all. To me it seemed like a fuse/circuit was tripped.

Is there any chance this thing has some kind of a circuit breaker or fuse inside? If so how difficult is it to open this bad boy up.
 
Yep, that was the issue. Before I came back here I took the back plate off and I took the battery out. Just for fun I tried powering it up and it came right on. So with it all apart I put the battery back in and it still powered on. Next I plugged in the parallel adapter and it came on for a second then off. I took the battery back out, put the parallel back on and it works fine.

My guess is that the battery that holds a one minute charge tries to draw too much when it is powered on with the parallel adapter and turns the whole pc off. I now have IrcJr running with my Xircom Pe2, how awesome is that.
 
Fairly common fault with old NiCd batteries.

I remember a Laser laptop (some sort of 286/386) which melted the case of its power adaptor. We thought it was a fault with the motherboard etc, turned out the battery had an internal short. Removed the battery pack and the adaptor never even got warm to the touch.
 
So now the trick is to crack open the battery pack and rebuild it.

I've thought about doing it a few times, but I really don't know enough about battery technology to do it. Replacing the original NiCD cells with new ones would be fairly easy; the existing charging system would work fine. Changing to a better battery technology (NiMH) would be an upgrade, but not terribly convenient if you could not use the existing charging system, or if the voltage is slightly wrong and the machine gets damaged.

(And I'm sure there are circuit tricks you can use to ensure equivalent voltage and current flow, but they are beyond me at the moment ... I should start doing a lot of reading.)

My L40SX needs a battery rebuild as well. All of the old machines will need them at some point.
 
The challenging part is to actually open these battery modules. They tend to be glued together tightly.

NiCd vs NiMH: the latter has a more strict charging end detection, I wouldn't just exchange them. IMO, as this NiCd/NiMH crap only lasts a few years at best don't put too much effort into it and just replace the old cells with similar ones, maybe with greater capacity if available.
 
H-A-L-9000 said:
The challenging part is to actually open these battery modules. They tend to be glued together tightly..
Click to expand...

Typically the earlier the laptop the easier it is. Even so you will most likely have to cut something to open them and then tape/glue it back. Some models have epoxy resin filled batteries which are impossible to open (Toshiba T2100 springs to mind).

One thing I did think of trying was 3d printing a new battery case and then using that. I never got around to it though as I rarely use my old laptops. Shouldn't be too hard to CAD up and 3d printing services are now quite plentiful around the place.
 
The IBM 5140 battery does have a fuse inside, according to old postings on usenet. The 5140 battery uses a standard connector and battery voltage as many batteries in the RC car and airplane hobby and they're fairly cheap (~$30). Is the fuse required or could you possibly use one of these RC car batteries?
 
I seem to remember if the battery is not able to pass through to the power supply it won't power on, I would need to re-check. I remember I figured it out, but I don't remember if I removed the battery or not to get the thing to boot. I can test mine if you need a 2nd opinion/test comparison.
Bill
 
The 5140 powers on without the parallel adapter and with the battery in place. The battery even holds a charge for about a minute. With the parallel adapter in place it powers on for one second and then off. Once this occurs I have to unplug the battery and plug it back in before it will try to boot again. With the battery unplugged and the parallel adapter in place everything works great.
 
H-A-L-9000 said:
NiCd vs NiMH: the latter has a more strict charging end detection, I wouldn't just exchange them. IMO, as this NiCd/NiMH crap only lasts a few years at best don't put too much effort into it and just replace the old cells with similar ones, maybe with greater capacity if available.
Click to expand...

Not so, I can tell you from nearly 20 years of replacing NiCd with NiMH in many hundreds (if not thousands) of pieces of expensive gear, they work just fine, even with just continuous trickle charging via resistor and a blocking diode, nothing more. Just be sure you use correct voltage and capacity - if you go putting a smaller battery in, then you might overcharge and have serious problems (like 'BANG!'), use the same capacity and good quality and you'll be fine. You can PM me if you want any details.
 
I should just add that some of the old PC's didn't use rechargeable batteries, some used other chemistries like Lithium or Alkaline and were often in the rectangular black boxes with the twisted red/black leads. I have no idea about this machine, but you would want to check that they were actually Nicad if you were going to change to NiMH - I'm sure the people here will know. If you do go NiMH, ensure you keep them topped up, don't let them drain for long periods (eg. 4+ weeks) or their lifespan will drop consierably. I was at a customer's the other day and the NiMH there was fitted by me 10 years ago and was still in great condition (when tested under load), but it's used daily except over Christmas and Easter.
If you are going to leave it in the cupboard for years, better to fit a removable battery.
 
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