IBM 300GL

[Retro6]

300GL prices are going up? It's just a business PC, nothing special.

It shouldn't be that slow I remember installing office 2000 on 486 PC's at 66 MHz years ago when I worked for a computer recycling place and they were quicker than this one I have. Oh boy I wish I had kept the 486 computers I used to have, I had about 15 of them because the place where I used to work no longer wanted 486 computers so people took them home that was back in 2003/4 when they were worthless and seen as junk but now each one would be worth 200 to 300 pounds and they were excellent reliable computers.

I will do everything I can to sort out the IBM 300GL and if I get no luck I will sell it on as it is or keep it and in the next 5 or 10 years it might be worth a lot more. I have ordered some more RAM. Just encase... the RAM was only 2 pounds each PC66 32MB and I bought the last lot of 2 sticks so I'll have 64MB in total. Its probably worth having spare old RAM anyway.

 

[MagicBoy]

I agree, it shouldn't be that slow. There's an issue somewhere. I used a P200MMX one for a year or so when I worked for IBM, although for some reason ours came specced with an ultra wide SCSI cards and fast HDDs.

My original point is that a custom built PC with carefully chosen components would be more valuable nowadays than a mass produced desktop PC from a large OEM for most retro gaming enthusiasts. Also easier to fix as it'd use a standard PSU.

 

[Retro6]

After looking at the errors I've been getting and the way the computer behaves all points to the RAM such as the computer suddenly slowing down Error messages such as "This software requires 4MB RAM or more" when clearly the computer has 32MB RAM and shows 32MB RAM in BIOS and in system information in Windows, it would also explain why the computer doesn't always power up first time and will give a continuous long beep indicating a RAM problem...

So maybe the SD PC66 RAM that I'm using is still perhaps a bit to modern for the machine. The RAM stick is good and has been tested. I was having a look on ebay and I noticed that there is some even older looking SD EDO RAM...

I've taken a few screen shots of some examples, so the first is the more modern SD PC66 RAM



This is the older SD EDO RAM which could be my answer to getting the this computer working correctly

 

[MagicBoy]

That chipset will use either EDO or SDRAM.

To be honest I'd stop plowing money into it, if the PSU or board appear to be problematic.

 

[Retro6]

That chipset will use either EDO or SDRAM.

To be honest I'd stop plowing money into it, if the PSU or board appear to be problematic.

I don't spend much on RAM just a couple quid here and there.

I may have had a breakthrough with this... so my IBM 300GL has the model number 670 and I've looked it up and that IBM 300GL Model used server memory.

 

[Retro6]

I've put the computer away for now and I'll be getting some server EDO RAM to try on it and if the problem remains I will try another power supply I can modify a standard ATX PSU by cutting and soldering the leads from the old PSU on to the ATX PSU all the voltages are the same. If the problem still remains then I'll junk the motherboard and I'll put the rest in the attic for a future project.

There's really no point in selling it because its very heavy and would cost quiet a bit to post and generally nobody would be interested in an old IBM that they will have to collect. There are a few old computers on ebay on collection only and nobody bothers to bid.

I got lucky... I won a nice Pentium PRO 133MHz PC for 35 pounds... well I say lucky now but I don't know if it works so it be a surprise and if the worse happens and it turns out to be another junk box then I have a fully working P4 motherboard to put inside it that's Windows 98 compatible so I'd be able to build a Windows 98SE gaming machine and the case looks ATX compatible.

 

[Retro6]

Oh well the seller never sent the Pentium PRO computer after all and I ended up getting a full refund. I expect the seller never sent it because he wanted more money for it. I'm not having much luck at all lately.

Back to the IBM 300 GL I've ordered the EDO RAM which is worth a try at least then I will know for sure if EDO RAM solves the RAM error problems as PC66 RAM may still be to modern for this old machine. If it works its happy days if not then it will get a complete revamp with another motherboard and PSU.

I have done the measurements of the back as I will need to cut away some metal so it can take a standard ATX mother board. There isn't much to cut away and then I'll be 3D cutting some perspex to cover up any ugly gaps around the I/O shield and I'll cut out 2 slots so I can fit a low profile video card and low profile sound card. Providing that I get no joy with the EDO RAM I'll be doing this mod. I already have a spare ATX P4 motherboard and PSU and then it will get a Windows 98SE install I'll also upload pictures on here once its done.

One thing I just realized is that the processor cooler on the P4 board sits a little high so there isn't much clearance between top of the IBM case so I'll need to cut and make a vent on the top of the case for better ventilation for the processor.

 

[Retro6]

So I'm still waiting for the EDO RAM to arrive which should arrive next week.

I have been doing a lot of thinking... before I do a revamp on this machine, I'm going to look at the fault in more detail providing the RAM doesn't sort the problem out.

So the fault at the moment still remains with the RAM error and the computer not always turning on first time with continuous beeping, I have to switch it off and back on again and normally after the second or third try it turns on with no beeping and runs as it should... this could indicate a PSU problem or a lose connection somewhere, the fault also could be a faulty capacitor in the PSU in which voltages maybe dropping on one of the voltage outputs of the PSU. It could also be that some of the resisters in the PSU have gone out of spec.

Now I have a few options if it is the PSU.

Option 1 diagnose and repair the PSU (if there are failing components) then its more likely to be a bad capacitor or two or some bad resisters. It wouldn't be anything else in this case as the PSU would not work at all such as transistors or diodes shorting out and in those cases the PSU fuse would blow or the PSU would go bang. A PSU can still work with bad resistors or failing capacitors but may not output clean voltages.

Option 2 (providing the PSU is the suspect) I have lots of working ATX power supplies I'm sure I could sacrifice one for capacitors to put in the IBM PSU providing that they are of the same value or close enough and I have bags of resistors.

Option 3 as said before I could just cut the connectors of an ATX PSU and solder on the connectors from the IBM PSU if they put out the same voltages 12v 5v 3v so that be straight forward.

If its not a PSU issue. Then it will be back to the systemboard. So what I will do is remove the system board and begin some trouble shooting. I will check all connections and joints and check things for continuity. I'll also check for any dry joints on the system board.

So I think I've covered everything there.

If I still can't solve the problem then the revamp will start.

The first stage now is to wait for the RAM.

 

[Retro6]

I've made progress and I've found the problem. The PSU is the culprit and the motherboard is in good working order.

So Now I just need to sort out the power supply and it should be good to go.

 

[almoststew1990]

If you want to test it with a modern power supply you could get one of these (ebay). I've used one on my 386 PC and it's worked fine for months.

 

[Retro6]

If you want to test it with a modern power supply you could get one of these (ebay). I've used one on my 386 PC and it's worked fine for months.

I've got quite a few ATX power supplies knocking about I've selected a 300Watt HEC-300AR-PT and I already have that ATX to AT adapter. I will just need to cut and solder the 5volt 3 pin connector from the old power supply to the new power supply.

 

[Retro6]

I've almost finished the new modded ATX PSU I managed to find a circuit diagram of the old PSU and work out what everything does so that when I plug the new modded PSU in to the motherboard I don't go blowing anything up on the motherboard.

It wasn't as straight forward as I first thought... there were also many connections rather than just two standard AT connectors the IBM uses four AT connectors, Two for the motherboard one to power the processor and the other is to power the PCI/ISA slots then there were two more connectors that are three pin plugs.

I've done most of it now so I've just got two more connectors to solder and that is pretty much it. I have all the correct color heat shrink for the wires as well

I decided not to use the ATX to AT adapter as the wiring is different for the IBM 300 series boards and I could burn something out on the board, if something ran on 3 volts or 5 volts and got 12 volts something will go up in smoke and that would be the end of that.

This is the wiring diagram I've been following for the AT P connectors.

 

[Retro6]

Update... I finished the power supply conversion I plugged it in to the motherboard and I was expecting something to go up in smoke but all is working well now I've just got a configuration error to sort out in the BIOS.

Next I've just got to trim a tiny piece of metal of the back of the case so that the new PSU can screw in, and then connect up all the drives. I don't have that RAM issue anymore neither.

Could anybody help me with this error I get in the BIOS? The error is nothing new its always been there but I can't seem to get rid of it its always there on start up I tried setting the BIOS to default settings but its like the BIOS is not saving settings... it has a new CMOS battery the only thing I can think of at this point in time is that the contacts of the CMOS battery socket isn't making good continuity with the battery which would be wishful thinking as that would be easy to repair...

Anyway I was just wondering if somebody could help me with this error.

 

[Retro6]

I've sorted all the problems out now. I've now got the IBM 300GL working correctly

 

[Donnie Fisher]

What sorted the bios ?

 

[Retro6]

What sorted the bios ?

Apparently nothing... its was working fine but some days later the BIOS error returned then it wouldn't even post after that.

I'm ditching the motherboard now there's nothing I can do. I've got another Micro Star 6787 motherboard "I had two of these boards that seem to be pretty good for retro builds" that will fit in the IBM 300GL case with a bit of modifying to the back of the IBM case so I'll be doing a rebuild today and I'll upload some pics of the new reformed IBM 300GL once its all done.

 

[Retro6]

So here is the new reformed IBM 300GL its not finished just yet I need to tidy it up a bit and the gap above the I/O Shield will be covered with a panel that I'm making. The pwr and HD indicators are working but don't show in the photos.

 

[Retro6]