Aquarius

Replacing the Caps

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Abstract:

Your Aquarius computer was probably manufactured between 1982 and 1983, so best-case scenario, the electrolytic capacitors inside are about 35 years old. Replacement ("re-capping") is a good way to ensure the non-replaceable components in your Aquarius don't get damaged from failing electrolytic capacitors.

Background

I got back into the retro computers of my youth in the Summer of 2018, working first with Commodore 64 computers, and then the Aquarius (my first personal computer). In nearly every forum, collectors recommend replacing electrolytic capacitors that are over 30 years old, as is the case with the Aquarius. Due to the analog nature of the power circuitry of the Aquarius, the board-level voltages of +5v, +12v, and -12v are created through a collection of about 16 components, five of which are electrolytic capacitors, and two of which have "oddball" ratings that are rarely used in the modern world of switched power.

Parts

While I don't list specific links to parts in a BOM (Bill of Materials) for this build, I do recommend you source the replacement parts from your local electronics supply store. With the loss of Radio Shack, it's more important than ever to support these smaller, independent electronics hobbyist stores.

In the event you can't find a part, THEN you can source them from a larger vendor such as Mouser.com or DigiKey.com.


  • 1 @ 10000uF - 16v, AXIAL
  • 1 @ 1000uF - 25v, RADIAL
  • 3 @ 10uF - 25v RADIAL (one of these three capacitors is rated at 16v, but for simplicity I've spec'd them at 25v... it's okay to use a capacitor with higher voltage, but don't change the capacitance)
  • 1 @ 2.2uF - 50v, RADIAL
  • 1 @ 1uF - 50v, RADIAL
  • 1 @ 47uF - 10v, RADIAL
  • You'll also need the usual soldering/de-soldering supplies and tools


Re-Capping Instructions

Below are the steps to replacement of the capacitors in video format:

1. motherboard removal

First, you have to remove the Aquarius motherboard from it's case.

2. RF Shield removal

Next, you need to remove the RF shield that encases the motherboard.

3. replacing the capacitors

Finally, you have to replace the electrolytic capacitors.

I don't go through re-assembly or testing, but, you know, duh.

optional: removing the power regulator

While you're at it, you can remove the 7805 power regulator so it can be replaced with a modern switching equivalent.

The first half of this video is removal of the RF modulator, which is not necessary for the re-cap process.

optional: replacing the power regulator

Second half of the optional process of replacing the 7805 power regulator with an OKI-78SR-5/1.5-W36H-C switching regulator.