In this instalment of Faulty Power Supply, we’re replacing a rather impressive collection of electrolytic capacitors. Will it fix the Sega TeraDrive? I suppose we’ll find out once everything is back together!

I’ve got the Hakko 808 ready for another evening of desoldering. There’s a mixture of components on this board, including some enormous low-voltage capacitors and a rather intimidating large capacitor on the primary side. I managed to order most of the replacement parts, although naturally some components were still on back order.

The power supply was giving me some rather unpleasant voltage readings, so I thought replacing the ageing electrolytics might be worthwhile. There were some enormous 6800 uF capacitors rated at 10 V, along with a collection of smaller parts. Some of the replacements were considerably smaller than the originals, which is rather interesting when you see them sitting next to each other.

The replacement parts have arrived, so I started removing the old electrolytics and inspecting the board as I went. It probably looked as though I was desoldering them at random, but there was a plan in there somewhere! A few came out fairly easily, but others were considerably more stubborn. Naturally, the largest capacitor was one of the least cooperative. I eventually decided to leave that one until later rather than spend the entire evening fighting with it.

Things became rather more interesting when I removed one of the Sanyo capacitors. There was obvious residue around its leads, and the surrounding board wasn’t looking particularly healthy either. That’s certainly the sort of thing I was hoping to find! The affected area was near part of the low-voltage circuitry, making it particularly interesting given the fault I’d been investigating.

There were some unpleasant deposits around other components too, including what appeared to be a deteriorated solder connection beneath a taller capacitor. I spent some time cleaning the affected areas, although it wasn’t always easy to distinguish old adhesive from electrolyte residue. The closer I looked, the more cleaning there seemed to be.

A second capacitor also showed signs of leakage, which made me feel a little better about spending so much time replacing components. At least we weren’t completely stabbing around in the dark any more. Whether either capacitor was actually responsible for the original power problem was another question entirely.

The big Rubycon capacitor, on the other hand, appeared to be in comparatively good condition. I couldn’t see evidence of leakage from that particular component. Quite reassuring, considering how much trouble it had given me just trying to get it off the board!

I also discovered that one of the original 4.7 uF capacitors was rated at 350 V, while the replacement I’d obtained was rated at 400 V. It was smaller, which is rather interesting considering how much capacitor technology has changed over the years.

By the end of the session, we’d identified some genuine signs of deterioration and made considerable progress replacing the capacitors. Unfortunately, I still hadn’t proved that any one of them was responsible for the original power-supply fault.

Next up, we’ll finish the soldering and find out whether all this work has actually achieved anything!

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