Preserving 386 PC long term

[mechaniputer]

Hi,

I have a 386 desktop machine from around 1991 that currently works (as of last year). The machine was custom assembled by my dad around that time and was used as the family computer long enough to end up with Windows 95 and an ethernet NIC. I would like to make sure it keeps working for the long haul.

This machine had a long history of expansions and is a bit of a rats nest. It has the following parts:

• Am386DX/DXL-33 CPU
• Fortron FS200-40 PSU
• Motherboard with AMI BIOS (can't see a model number without disassembly)
• 8 MB RAM
• a hard drive
• 3.5" floppy drive
• 5.25" floppy that was retired but left in place (actually looks like it is still powered but no data cable)
• Yes, a turbo button

Here are the cards installed, going from right to left from the back side of the machine:

• Vortex VGA card
• 3COM Ethernet NIC with 1997 Copyright
• Some kind of serial mouse+floppy interface card (serial mouse port, plus the 3.5" floppy ribbon cable, and external serial/parallel ports) This card has a second external header connected,
• Creative CT2770 sound card
• A small card with ribbon+audio cables to the CD drive

My main concern is the caps and batteries. The motherboard seems to have one cylindrical 3.6v battery with a lead on either end, soldered on flat. There are also a TON of electrolytic caps on the sound card. I don't see any damage visually (but I haven't opened the PSU).

I try not to power it on very often because the PSU could fail and destroy the rest of it. I'm even a bit nervous to move the dust around too much, but a full disassembly and cleaning is probably in order, taking note of where everything is plugged in. Once I've gone over everything (after the advice I get here) I'll probably use it much more often.

And now, some questions:

1. Does anyone have any suggestions or tips for when and how to replace the caps and battery?
2. Is there a place I could mail the PSU (and/or sound card?) to get it completely recapped?
3. Is there any other preventative maintenance I should be doing?
4. I know the hard drive will have a finite lifespan. Any tips on the best solid-state replacements available?

 

[mechaniputer]

And just for posterity, here is a picture of the machine.

 

[Timo W.]

If the caps are fine, don't replace them. Most old caps don't leak. Replacing them for no reason is an unnecessary risk of causing damage.

As for the battery, just cut it off. You can then either add a holder for a CR2032 coin cell (needs a diode to prevent charging) or attach an external battery pack using the pin header near the old battery (assuming there is one, but there should be).

For the rest: USE the system from time to time, as that is what it was meant for. Also, this will keep the system going, as the caps need power from time to time and it will keep the mechanical parts from getting stuck. Put it into storage for 5 years and you can expect it to be broken next time...

And no matter what you do, it will eventually fail anyway. So have fun with it as long as it is working.

 

[mechaniputer]

And no matter what you do, it will eventually fail anyway. So have fun with it as long as it is working.

Sure, but it would be nice if it fails in a repairable way. If the PSU blows and fries the board and CPU and RAM and ... etc then there's not much to do about it. On the other hand if the hard drive or RAM or BIOS ROM fail, or any of the individual boards, there are modern solutions to keep it going. I'd just like to prevent anything catastrophic and keep it repairable as long as possible. The machine is already over 30 years old. Another 30 would be nice and I believe that it is in principle possible.

 

[Timo W.]

If the PSU blows and fries the board and CPU and RAM and ... etc

Let me guess: you saw one of Adrian's videos in which that happened..? It's a very rare case and replacing the caps won't have any impact on that. Normally, when a PSU goes bad, the voltages are too low or it does not even start regulating any voltages at all and stays completely dead.

Except for the usual faults, like a NiCd battery or known-to-leak SMD caps, there is no need to fix anything on a system that is not broken.

 

[mechaniputer]

Let me guess: you saw one of Adrian's videos in which that happened..?

I don't know who Adrian is and I haven't been watching videos. I just have several friends that this has happened to. I don't think it's as rare as you say. It's well known that a bad PSU can damage other components. It might (possibly) be less than 50% of PSU failures, but PSU failures in general are common enough that I am willing to expend money and effort to prevent it. I make a point of using newer (modern replacement) PSUs with several of my vintage Apple and Commodore systems for this reason.

So once again, does anyone know of any reputable PSU recap services?

 

[mechaniputer]

Decided to do a full disassembly for the sake of cleaning out all the dust and removing that battery. See attached pictures. Looks like it is soldered pretty tight against the board. Does it look like I should de-solder it or try cutting it?

Thanks.

 

[seaken]

No, I don't know of any PSU recap services. But you could share more information about the maker of the PSU. How do you know it is going to go bad? Unless it is some piece of junk that should not have been put in there in the first place. I have over 35 systems from that time period and all of them are working fine. What brand?

Anyway, I agree with Timo, use the computer regularly and chances are that the caps are fine. If they were of poor manufacturer they would have gone already. 1991 was a pretty good time for builds. Lots of quality still. Later, things did go down hill as price wars happened. But your dad built this right? Was he going for cheap? Or did he use good parts?

I would look for replacement parts or maybe a similar system to have as backups. I always had a couple of backups when were were using those systems in our business, or at least more than one in service. As time went on I accumulated more backups as machines were less costly.

Seaken

 

[seaken]

Yes, that is a Varta barrel type battery. I just use some side cutters and clip it off carefully. You may have to take little snips at it. Once you get the first side you can bend it up for easier access to the other side.

Do you have a manual for the motherboard? If not I would look for one and keep it in your library. Look for an external battery header. If thee is a battery header it will be easy. Just attach a battery carrier and use 3 or 4 1.5v AA batteries. This carrier should have a red and black wire with a connector. Put the red wire on the positive pin.

If there is no external battery pin header then start reading up on adding a CR2032 carrier. Some additional modifiers will be needed. You can't just attach the CR2032 to the leads from the barrel battery.

Seaken

 

[maxtherabbit]

I just have several friends that this has happened to.

I'd wager they were using trash tier ATX supplies from the early 2000's. Old AT supplies are nowhere near as problematic. Failures in AT supplies that cause downstream damage are *exceedingly* rare

 

[seaken]

It's also more likely that some of your reports from friends are not technically correct. Maybe. But consumers tend to misunderstand some of the technical aspects.

Commodore , Atari, and to some extent Tandy, were early in the price wars for consumer level computers. Then the PC compatibles got caught up in it and this did sometimes lead to sub standard equipment - or junk. But there was still a lot of good stuff. Our business tended to stay away from the low price point. Hopefully your dad also studied a little bit and got some good equipment instead of junk. Most DIY builders would not spend money on junk. But sometimes a consumer might get fooled by a low price and end up with a junk power supply and a chintzy case.

Seaken

 

[mechaniputer]

Thanks everyone.

PSU is a Fortron FS200-40. No idea if it is considered a good model. Supposedly money was tight when he built it, but computers were both a passion and a livelihood so who knows.

Either way it sounds like there is a clear overwhelming consensus that I should let it be. I'm convinced now, unless someone jumps in with bad news about that model. I'll snip out the battery, finish blowing all the dust out, and start reassembling it. I don't have the board manual but I found the layout here, and it looks like there is an external battery header, which is nice.

 

[the3dfxdude]

I don't know who Adrian is and I haven't been watching videos. I just have several friends that this has happened to. I don't think it's as rare as you say. It's well known that a bad PSU can damage other components. It might (possibly) be less than 50% of PSU failures, but PSU failures in general are common enough that I am willing to expend money and effort to prevent it. I make a point of using newer (modern replacement) PSUs with several of my vintage Apple and Commodore systems for this reason.

PC power supplies have been built with some protection in mind. They do not usually fail catastrophically and damage components. There were some issues with really bad PSU makers right around the time there was a race to the bottom in price. 1991 machines were not in this era. Despite the tale of power supply destruction, I have seen more of bad parts straight from the store or even user error causing destruction than eventual power supply collateral damage. If it worked last year, it is probably fine. It doesn't hurt to do a visual inspection, though.

 

[modem7]

... and it looks like there is an external battery header, which is nice.

Presumably, your motherboard automatically 'selects' the battery (soldered in, or battery header). See [here].

 

[T-R-A]

I try not to power it on very often because the PSU could fail and destroy the rest of it. I'm even a bit nervous to move the dust around too much, but a full disassembly and cleaning is probably in order, taking note of where everything is plugged in. Once I've gone over everything (after the advice I get here) I'll probably use it much more often.

NOT using the machine is probably one of the worst things you could do when it comes to capacitors. Non-use wil almost certainly cause them to dry out. As mentioned, remove the battery ASAP to prevent corrosion and replace with something external from the motherboard.

 

[mechaniputer]

Successfully removed the battery, cleaned out the dust, and reassembled it. Everything seems to be mostly working.

I did find that the IDE card is a bit finnicky. I had to re-seat it several times. I kept getting 2 high beeps, 8 low beeps and no graphical output. I tried cleaning the board contacts and I think it helped but I still had to re-seat it a couple times before it worked. Perhaps the slot is dirty. I'll have to go back in and do something about that later, but for now, at least I know it all nominally works.

 

[creepingnet]

NOT using the machine is probably one of the worst things you could do when it comes to capacitors. Non-use wil almost certainly cause them to dry out. As mentioned, remove the battery ASAP to prevent corrosion and replace with something external from the motherboard.

I second the emotion here.....sometimes the Caps - if being wonky can kinda' "rebuild" under frequent use. That's been the case with several of my vintage computer items including my NEC MultiSync II CRT (that thing is so perfectly bright and sharp now It's hard to not want to use it), NanTan Notebook FMA9200C (LCD Panel circuitry is coming around to where it's starting to look like a new panel).

I think the whole "Shotgunning" capcitors thing is ridiculous and unnecessary. I think in the time I've had to deal with capacitors on any vintage device, it's been my 1993 Ford Explorer's ECU (t's a vehicle so outdoor in the elements), one Television (Mitsubishi CS2720R), and a MODERN LCD monitor that had bad caps that I pulled from a dumpster (which then blew in a few months from another issue eventually anyway).

 

[Caluser2000]

I second the emotion here.....sometimes the Caps - if being wonky can kinda' "rebuild" under frequent use. That's been the case with several of my vintage computer items including my NEC MultiSync II CRT (that thing is so perfectly bright and sharp now It's hard to not want to use it), NanTan Notebook FMA9200C (LCD Panel circuitry is coming around to where it's starting to look like a new panel).

I think the whole "Shotgunning" capcitors thing is ridiculous and unnecessary. I think in the time I've had to deal with capacitors on any vintage device, it's been my 1993 Ford Explorer's ECU (t's a vehicle so outdoor in the elements), one Television (Mitsubishi CS2720R), and a MODERN LCD monitor that had bad caps that I pulled from a dumpster (which then blew in a few months from another issue eventually anyway).

I concur. I've only had one PSU go out in the 30 plus years I've had dealing with XT/AT era computers.

 

[davidrg]

I think the whole "Shotgunning" capcitors thing is ridiculous and unnecessary. I think in the time I've had to deal with capacitors on any vintage device, it's been my 1993 Ford Explorer's ECU (t's a vehicle so outdoor in the elements), one Television (Mitsubishi CS2720R), and a MODERN LCD monitor that had bad caps that I pulled from a dumpster (which then blew in a few months from another issue eventually anyway).

This depends on the machine I think.

For example, the PSUs in the lunchbox SPARCstations (IPX, IPC, etc, and the Sun 811 disk enclosures that go with them) absolutely must be recapped. Even if they look fine those capacitors will leak sooner or later and make a big mess in the process. And it's a whole lot easier to do the job when the PSU PCB isn't soaked in corrosive electrolyte. One of the 811 disk enclosures I have got so bad that one of the capacitors actually fell out of the PSU when I turned it upside down. I've not seen any caps in the pizzabox SPARCstations leak yet but given they use the same brand I have to wonder if it's just a matter of time.

That said, it's a whole lot easier to get a replacement AT PSU than a replacement SPARCstation PSU so I've never bothered to recap AT PSUs. I've never seen one go out with a bang taking other components with it so I'd just use it if it works and replace it with another one if someday it stopped turning on. Perhaps if I was planning to leave the machine running unattended 24x7 I might treat it differently though.

 

[maxtherabbit]

This depends on the machine I think.

For example, the PSUs in the lunchbox SPARCstations (IPX, IPC, etc, and the Sun 811 disk enclosures that go with them) absolutely must be recapped. Even if they look fine those capacitors will leak sooner or later and make a big mess in the process. And it's a whole lot easier to do the job when the PSU PCB isn't soaked in corrosive electrolyte. One of the 811 disk enclosures I have got so bad that one of the capacitors actually fell out of the PSU when I turned it upside down. I've not seen any caps in the pizzabox SPARCstations leak yet but given they use the same brand I have to wonder if it's just a matter of time.

That said, it's a whole lot easier to get a replacement AT PSU than a replacement SPARCstation PSU so I've never bothered to recap AT PSUs. I've never seen one go out with a bang taking other components with it so I'd just use it if it works and replace it with another one if someday it stopped turning on. Perhaps if I was planning to leave the machine running unattended 24x7 I might treat it differently though.

I agree with this. There are known bad brands/series/applications where recaps should always be done. But trying to say that all old caps should be replaced simply due to age is foolish.