Retro Computing Grotto: How to (Attempt to) Repair a Compaq Contura 4-25 Laptop

Friday, 27 March 2026

How to (Attempt to) Repair a Compaq Contura 4-25 Laptop

*This Page Is Under Construction and Will Change As I Add Updates To It*

If you're interested in this repair journey then please bookmark/save this page/URL as I will be updating it with more photos etc. as the repair(s) progress..

Last year I picked up a Compaq Contura 4/25 laptop from the 1990's and it failed its initial testing - I got some 'Magic Smoke'!!

Follow me on it's repair journey..

Here is the post-it note I taped to the screen:

Fault 1: Magic Smoke
Fault 2: Hinge Damage

As I was taking apart the laptop to look at lubricating the hinges I got distracted as I noticed the power board is separate to the main board (hopefully) making a repair a lot easier!

Hinge Damage

Time to go topless so I need to remove the screws..

Now these are what I call screws - around 1" (2.54cm) long!!

Now I can take it's top off..

Then remove the top metal cover and keyboard

Magic Smoke

With the top cover removed we can now see if we can find out where the magic smoke came from..

Ooh! The power input board/PCB is separate to the main motherboard PCB so lets take a closer look..

I'm looking for a blown capacitor

There it is!!

Now all I need to work out what value it is.

It looks like it is a 2.2µF 25V capacitor and I think it's a Tantalum one but to be sure I have posted on the BadCaps forum and I have also asked AI (CoPilot):

Q: Here is a photo of the power circuit board from a Compaq Contura 4/25 laptop i believe it is a 25V 2.2 microfarad capacitor - can you help confirm this and what type of capacitor is it so I can order a replacement. For example is it a normal ceramic capacitor or is it a tantalum one?

A: You’ve identified it correctly — and the photo gives us enough detail to be confident.

✅ What the component is

The markings:

25 → 25 V rating
2U2 → 2.2 µF (the “U” stands in for the decimal point)
+ → Polarity marking

This combination is characteristic of a tantalum capacitor, not ceramic.

✅ Type of capacitor

It is a solid tantalum chip capacitor (also called a “molded tantalum” or “tantalum bead” capacitor).

How we know:

The yellow epoxy block package is classic for older tantalum capacitors.
The polarity “+” is almost never printed on ceramic capacitors.
The 2.2 µF / 25 V value is very common for tantalum in 1990s laptop power circuits.
The cracked casing is typical of tantalum failure (ceramics usually shatter differently).

✅ What to order as a replacement

You want:

2.2 µF
≥25 V (you can safely use 35 V or 50 V if the size fits)
Tantalum, polarized
Same package style (likely “A case” or “B case” depending on dimensions)

If you want to be extra safe, you can replace it with a tantalum polymer version — they’re more stable and less prone to catastrophic failure — but the original form factor is fine

I shall wait and see what they see on the BadCaps forum as I trust them a little more than I do AI..

If AI is correct then this is a potential replacement:

https://cpc.farnell.com/multicomp-pro/mccb1e225m2acb/capacitor-tant-2-2uf-25v/dp/CA05690

Other Things of Note

RAM

CMOS Battery

I've never seen one this size before so I've had to order some Toshiba branded ones from Amazon (5 for £4.40) so fingers crossed I can repair the power PCB..