Dell Dimension XPS T500 revival project

Let's begin with a "beauty shot" of my old Dell machine. I decorated with some rotting autumn leaves. It's symbolic.

This 1999 machine was actually my first PC. Naturally I had owned computers before this, but here in Sweden we had our own term for personal/home computers. PC meant boring IBM / windows computer, and that's what this machine was. It ran Windows 98, and I used it for surfing, games and art (Photoshop 5.5 + Wacom Intous 1 A4 + Agfa Snapscan 1236u).

I replaced it with another Dell Dimension around 2004, which is still in use somewhere running a SCSI card + scanner. These older machines are useful for legacy support, so I though I'd try reviving the T500 too. It did boot up a few years ago, but made so much noise I turned it off.

There are four possible sources of noise: The chunky IDE HDD. The 80mm PSU fan. The 92mm CPU fan. The acoustics of the plastic CPU hood. All these sources can be addressed, I thought.

Dell Dimension XPS T500 exposed. Here I have removed the cooling hood going over the Pentium III CPU card. My machine came with a (Dell specific?) RIVA TNT2 M64 32MB in the AGP slot. Honestly, I'm more of a software-render person when it comes to games like Quake and Tribes. The network and 56-modem PCI cards were both dead and have been since removed. ISA slot at the bottom. I just noticed that the memory chip area on the graphics card has several cleverly offset footprints, likely so they can solder on whatever memory chips makes sense at the time in terms of availability/price.

Look at this peculiar Pentium III CPU card. Strange gap with heatsink glob? Apparently this MoBo is of a custom "ATX Slot 1" type. Anyways, these first two photos were from 2015 and that will matter later in this story.

Possible HDD replacement

This motherboard has a 3.5-inch HDD with a 40-pin IDE connector. There are IDE Adapters for Compact Flash, SD cards and SATA. SSD drives with IDE connectors are also available. A PCI-SATA card might not work as a boot device. The adapters require no drivers but may have issues with cable-select, poorly advertised directionality, shoddy soldering. Some are 44-pin and I don't want to have to stack adapters. I read that grounding pin 34 will make adapters faster as it enables "UDMA5", which is faster than PCI card SATA. The green adapter (JP103-5) with two black caps works for some, and it's only 3 euro... Unfortunately, some very nasty protectionism by the customs/post office here in Sweden means an added substantial fee to all China purchases, making it unfeasible to buy stuff unless you manage to get it all from the same seller in one package to mitigate the fee. It's the equivalence of adding a $10 entry fee to all specialised dollar stores run by "suspicious looking asians". It's important that some of us blonde ├╝bermench get to sell the exact same goods at 5-20x markup, having added so much value to the product in the act of reselling.

I'd like to use a Sandisk 120GB SSD, as they are cheap even on amazon (26 euro), light, and I've had no problems with them so far. However, Windows 98 will probably use the drive as virtual memory excessively unless disabled. It might not matter though as I likely won't have the machine on much. Also, at desktop idle, Win98 won't really fiddle with the drive at all.

Another solution is to use an old laptop IDE drive as those are much less noisy. Then I'd only need a simple 40-44pin adapter. My old ones all have a SATA interface though.

FANS

The fans can be replaced, but silent models are quite pricy and how much do I want to spend on this project? The normal price range seems to be 5-12 euro. I powered up both fans using my bench power supply, and they are quiet at 5V but less so at 8V. I think fans usually run at 12V, possibly with some kind of custom PWM, though these fans are all 2-wire. Supposedly the machine runs safely without the plastic hood if the case has proper airflow, but it seem to me the Pentium III CPU card is very much made to be cooled from the top.

I discovered later that the hood is responsible for most of the noise in the case and the CPU idles at about 45 deg. C without, case open. The passively cooled video card heatsink was hotter at 55 deg. C. HDD is very noisy but only during read/write.

The CPU cooling hood components cleaned.

PSU

The PSU was attached with two screws on the back. There's a L bracket inside but it was not attached to the roof of the case for some reason. The big connector going off to the motherboard has a little tab to squeeze or it won't detach.

At first I thought I would not be able to get into the power supply, as it looked like it had been machine-folded into an impossible puzzle-cube, but there were just three screws and it came apart easily.

Why bother taking the PSU apart? Well, at first I thought I'd just get a new, silent ATX PSU, maybe even a Pico, but it turns out T500 uses a custom one. The ATX1.0-like connector (P1) has a different pinout, so a regular ATX PSU might fry the board. The PS-ON wire is in a completely different position.

There's also a 6-wire auxiliary power cable (P7). There's no ON switch, the fan is rear-facing and designed to fit the custom back-plate. Maybe I can still use this PSU if the caps are fine? I could recap at some point.

Looking inside, I see two large bulk filter capacitors. There's no residual voltage, so I measure continuity across. OL. which is fine I suppose. It's hard to measure capacitance in-circuit. One cap has very a very subtle dome but I don't know if it's just the plastic top. The datecode is 99 37 and 99 43 for the PSU case. There was actually some industrial espionage drama around that time with a "stolen electrolyte formula that was missing crucial ingredients", causing a "capacitor plague". However, those caps went bad long ago.

Inrush circuit components look fine. Fuse has continuity. The various smaller caps all look fine. There are two unusual ICs, DNA1001D and DNA1002C. The 2-wire fan is connected to a daugherboard which has transistors, resistors and small caps... possibly a HFO/PWM driver?

Closing it up: pay attention to the tab near the cable hole. After mounting in case, also remember to push the PSU in sideways before tightening rear screws or the case won't close.

RAM

I'm seeing a three sticks, 128,128 then a 64 I must've added (center slot), then there's the 32MB GPU (counted towards total system memory during check).

CMOS battery

This is a 3V CR2032, likely dead. Yes, I later measured 0.1V left.

////////////////////////////////

Power on!

////////////////////////////////

Fans. A chirp from the HDD but no other activity.

I go through the process of checking connections, reseating things, and eventually discover that back when I last fiddled with the machine in 2015 I had not pushed down the CPU card properly. I also replaced the flat CMOS battery (the CMOS settings were long lost but I wrongly assumed defaults would be used). After that it booted, but I got two PC speaker beeps and nothing more.

Fortunately the BIOS could detect a USB keyboard, and holding Del (as in "Dell", get it???) at the logo got me into some sort of hardware check and then the BIOS. I set time but changed nothing else, saved and exited, and then I was able to boot into an old but barren Windows 98 install.

...

...

Every time I boot a Windows machine I get depressed. What a bloody dystopia it is. Humanity really headed down the wrong path. We're done for.