View Full Version : IBM PC 5150 NOT Working :(

September 17th, 2006, 03:08 AM
Hello !
This is my first post ever here, and I apologize because it is long and boring.
So, I have found an IBM PC 5150 complete with its monitor (5151) and keyboard. The pc comes with 2xflopyp drives, a hard disk (20mb) moutned on an isa slot, a hercules video card and a ram extension.
I cleaned everything ,plugged it and turned it on but nothing happens :(
I don't have much experience with these machines : my first pc was a PS/2 model 30 and I only used the original PC a few times at my dad's job :)
So I have a bunch of questions :
- When I turn the pc on, the fan turns and I hear little noises, but : nothing on the screens and no beeps, and the floppy doesn't activate. Should there be beeps during boot up like on later pcs or not ?
- The monitor doesn't seem to react at all. Always black, no noise, no heat, nothing. There isn't an on/off swith on it right ? The problem is I don't have an other monitor to test, at least not one wich could plug on the card.
- Any clue what could be wrong with the machine or mrthods to track down the incident ?
- Why can't I find any downloadble PDF versions of the 5150 manuals and docs, while there are tons of such documents for any other machine (macs, atari, commodore, etc...) ?
I'm surprised to see that information is very scarce about this machine. And that also explains my post. I usually find all the infos I need for my old machines by googling. But for the 5150... nothing, I mean nothing interesting beyond the hundreds of sites stating that it is the first PC, etc... blah blah.

Thank you very much for your attention. Your help will be very appreciated.

September 17th, 2006, 03:14 AM
Sounds like a PSU problem. You said the fan turns. Does it turn indefinitely or just budge?

As for documentation, there's a sticky somewhere in a forum with links to great resources of documentation. I haven't checked if I could find the 5150, but hey, if I can find Xerox Alto documentation, I can find just about anything on those links! :p

September 17th, 2006, 03:41 AM
I recommend to get PSU out and heck with old hdd (one, that is not expensive).
If it will turn up you can eliminate PSU.

Would be good if you meansure voltages from PSU.
Remember, that something must be connected to the PSU.

Also check verion of PSU, if it's old ~63W PSU it might not handle the disk (but if it's hard card it should).

People don't like 51xx PC's ;).
That's why you can't read something interesting about 'em.

I haven't seen 5150 docs in PDF, but 5160 are online.

September 17th, 2006, 04:11 AM
Thank you very much guys.
I'll have a look at the PSU first and measure the voltages. Just one thing : when you say it must be connected to something... what do you mean ? It should remain connected to the motherboard for eg ? I could harm it if I just plug it as is ?

September 17th, 2006, 04:20 AM
PSU must be loaded with eg. HDD.
If it will be not loaded it might not give you any voltages.

I haven't checked that, but every one say so.
Nothing wrong will happen if PSU will start non-loaded.

September 17th, 2006, 04:58 AM
Temporary remove all cards exept video adapter. Reseat all chips in sockets on motherboard.

September 17th, 2006, 05:04 AM
Ok I checked the voltages and everything seems ok. It outputs +5 +12 as it should.

Must be something more serious :/

September 17th, 2006, 05:40 AM
Have you any replacement cards?

Try to leave only motherboard and if it's good it sould beep few times.

Your PSU is 63W one or 130W?

As Elar said, remove all cards except video card.
You don't need to reseat chips on mobo, fist try to get it runnin only with Herc card.

September 17th, 2006, 06:04 AM
Don't start ripping the machine apart yet.

[1] The 5151 gets its power directly from the power supply. There is no on-off switch. If the machine powers on, it will supply power to the 5151 and it should come active. If it does not, then there may be a fault in the power supply of the machine or a fault in the 5151. It could be as simple as a blown fuse in the 5151. You can easily check the output voltage of the receptable on the power supply using a multi-meter, so don't start swapping stuff until you've tested it.

[2] The boot process is extremely long on these machines. In the trade we call it 'submarine mode', because it seems to disappear for a while before you see it again. If a monitor is connected and working you won't see it counting memory or doing anything except for a blinking cursor in the upper left. The amount of time it takes depends on how much memory is installed. Let it go for at least 3 or 4 minutes before you give up on it. At the end of the 3 minutes you should hear it try to boot from the floppy drives.

If it is still not booting then it's time to check the power supply outputs to the motherboard. The fan in the power supply is running so it is not completely bad. In general, power supplies are very reliable.

[3] If none of this works, then it's time to start removing extraneous pieces of the machine. If you suspect a bad monitor I would put in a known good working monitor and video card combination, remove the existing Hercules adapter, and set the motherboard switches to reflect the change. This will let you see if the monitor is bad.

If that doesn't do it, then remove all cards except for the video card. Get rid of memory cards, the floppy controller, etc. This machine has enough memory on the motherboard to boot into Cassette BASIC, and all you need is a video card - nothing else. Remember the order in which you remove things so that you can put it back together correctly.

If you are serious about debugging this, get a copy of the Technical Reference manual. There are no PDF versions - this machine predates PDF files by quite a few years. ;-)

Other obvious notes:

1. When in doubt, stop and look up what you need.
2. Use a static strap. No point in frying something while trying to fix it.
3. Never assume anything.

September 17th, 2006, 07:07 AM
- The PSU is 63 W and outputs power to the monitor correctly

- There's no blinking cursor on the screen, there ain't nothing :)

- Even after 5 minutes, nothing else happens.

- I checked the two psu outputs to floppies and they deliver 5 and 12V as they should. For the motherboard, it delivers power too, but I don't know exactly how much it should deliver on each of the connections. I'll look for that on google.

- I don't have another monitor/video card to test. I'll have to look but it will take some time I guess :)

- Even when removing all cards, doesn't boot.

- For the PDFs, of course I did't mean original ones. But usually I can find scanned PDFs of old documentations. It is not the case for this machine.

Ok that's all for now. I'll start looking for replacement parts and documentation before going any further.
Thanks again for all of your contributions.

September 17th, 2006, 07:10 AM
You can blame mainboard.

Am I wrong here Mike? ;)

September 17th, 2006, 07:36 AM
You can blame mainboard.

In a perfect world I would have a spare part of each component and i could tell if it's the mainboard by simply swapping it. Alas that's not the case :huh:
I'm afraid it could be a mainboard issue indeed.
Oh by the way, I noticed that besides a binch of chips that are from AMD, the processor itself is not an intel but an AMD. i think it has been changed by its previous owner. I knew there were NEC clones of the 8088 (i have an old zenith portable running one of these) but didn't know AMD also had 8088-like processors.

September 17th, 2006, 07:44 AM
It's starting to look that way. At least we know it isn't the power supply now that it's been properly tested. ;-)

Look for loose connections that might be causing a short. If a trace on the motherboard is touching something that it shouldn't, that's a good sign.

You can also probe points on the motherboard for power as well. Be very careful while doing this. The leg of an IC is usually a good place, and you can use a test probe with a hook to cut down on accidents.

BTW, AMD was the second source for processors, not NEC. AMD made 8088 processors under license from Intel, so they are exactly the same. The NEC V20 is a reverse engineered 8088 compatible which is slightly faster, and can be slightly incompatible. IBM always insisted on dual sources for critical parts, which is why there are IBM PCs with original Intel 8088 and AMD 8088 parts in them.

September 17th, 2006, 11:10 AM
It sounds like my first IBM XT. That had exactly the same problem, and it was a dead mainboard.

You can check for damaged components on the mainboard, or maybe something is causing a short. You might find some blown capacitors.

Have to checked the DIP switch settings to make sure they are correct?

September 17th, 2006, 02:38 PM
Yes I have checked the DIP switches to match the configuration. There's only one point I wasn't sure : for the video mode. Didn't know wich to chose for a hercules card. But I tried all the modes anyway and none did change the situation.
As for tracking damaged components on the mobo this way, way beyond my skills. I love old computer a lot but I'm unfortunately not a specialist in hardware at all. I can measure some voltage here and there with my multimeter, replace cmos batteries etc. but that's all. So I'll start a quest for a working 5150 mobo. That's my best bet to get my machine working.

September 17th, 2006, 03:04 PM
There have been a couple on eBay recently, worth keeping an eye open there :)


September 17th, 2006, 03:24 PM
If you replace the motherboard, put it in a nice static bag on a shelf one day. You never know when you might want to try to repair it.

Schematics for these things are common and easy to find. The IBM Tech Ref manual and the Sams Computerfacts are two sources.

September 17th, 2006, 10:52 PM
There have been a couple on eBay recently, worth keeping an eye open there :)


Oh yes, I started looking on ebay. But you see, the problem is that I'm located in France and alas us ebayers rarely send to france. I don't blame them for that, for shipping services are very unreliable unless you pay extraordinarily high shipping prices, and items usually get "lost". That's discouraging for both sides indeed. For eg according to my own experience, I never recieved about 30% of the items I bought in the US !
So I'm starting to post in some forums around, looking for such a mobo. But these machines are not so common here and it will probably take me some weeks/monthes to find one. But i'm not in a hurry :)

September 18th, 2006, 06:10 AM
To be honest, it is really hard to find a working mainboard in Europe without having to buy a whole computer. Shipping a mainboard from the US costs about $10-15, most sellers will send abroad if you ask nicely :)

Just make sure it is well packaged.

October 3rd, 2006, 01:20 AM
I'm back because I have some good news. I bought a 5150 motherboard on ebay and recieved it this morning. I installed it, and my 5150 came back to life :D
I'll keep the old defective card for spares. But, I think it must have a serious problem : if it didn't boot at all and show post error codes it couldn't be just a memory chip or something similar right ?

October 3rd, 2006, 01:57 AM
If it was me, think I would just leave the dead one on a shelf somewhere but ....

Sounds like "oxide control time" meaning carefully removing any chips that are in sockets and cleaning the oxidation off the leads. I use a regular pencil with a nice eraser, using the eraser on each lead to shine em up. Not a 5150 expert myself so unsure if anything is in sockets or all just soldered in place. Of course, you are going to carefully make notes as to the pin 1 location on each chip. I'm fairly sure they try and design the MB with all the pin 1 pointing the same way but I have seen boards where this isn't the case.

This could help the dead MB or not. If some voltage regulators on the MB have died, the above is a total waste of time.