Keeping and 486 and Pentium PCs going - A few Repairs and Mods

I grew up with PCs. My first one was a 486DX-33Mhz with 4Mb of RAM (I still have the order sheet somewhere) which was an ok machine at that time (1994). I had a lot of fun with that machine, it served me well for almost 2 years, when it got replaced by a much more powerful Pentium 100MHz with 16Mb of RAM, which was later paired with a Sound Blaster AWE 32 with 2Mb or RAM!

Here is a shot of my first PC Tower (extra points if you guess the game on the screen):

My very first 486 PC on display - circa 1994

In the past few years, I was lucky enough to find a vintage PC that came in a nice and classic mini AT Tower (I love the "Vader" vent design in the front). Inside the case, a working 486DX-33 motherboard, with 4Mb of RAM (as my 1st PC!):

The 486DX-33 board after some dusting

The CMOS battery (from Varta) has started to leak - a bit of corrosion is evident on the keyboard connector shield

Old CMOS Battery removed

Motherboard without the CMOS battery

Removing the battery corrosion residue with Vinegar

I lated added a battery holder together with a diode to replace the original rechargeable CMOS battery by a non-rechargeable 2032 coin battery. 

Before using a vintage computer, it is always a good idea to replace the capacitors of the the old AT power supply. I inspected my newly acquired PSU and bingo! I saw evidence that the caps have leaked.

PSU under going a recap

A few months later, I came across someone selling a Pentium 100Mhz motherboard, which it was my 2nd PC, that I kept for 3-4 years.

My Pentium 100Mhz motherboard!

My vintage case did not come however, with the very cool 7-segment clock speed indicator. You got have that! I then went to AliExpress and bought 3 small 7-segment green leds and built my own on a breadboard.

Figuring it out the led combination to display "100"MHz (blazing fast!)

Installing the clock display into the AT Case with the help of 3D printed part and hot glue!

Adding an independent fan controller to further reduce the noise of my new CPU fan (the original CPU fan bearing was very noisy!) 

My vintage AT case with its new clock speed led display showing "100"MHz!

Testing the Floppy Drive after being cleaned and lubricated: 

After installing a Sound Blaster 16 into my new old rig, I noticed the left channel was very low, hinting to a potential cap problem. Time to investigate and recap the SB16:

SB16 Value in its glory (with a muted channel)

SB16 during the recap process

Problem found! Cap measuring nothing

All caps with a black dot were replaced - no more muted channel issue!