Substitutes for GSC T18C 1500uF 6.3V caps

I'd probably recommend something like a Panasonic FC or FM series capacitor - 105-degree-C rated, designed for switching power supply applications.

I'd guess that's a 5 mm pitch?

Panasonic FM series has a 6.3 WVDC 1500 uF cap, 10 mm diameter, 20 mm high, 5 mm lead pitch - their part number is EEU-FM0J152, Digikey part number P12343-ND, Digi-Key price $0.59 each.

You might want to go up to a EEU-FM0J222L, P12344-ND at $0.61 each - same diameter, same pitch, same voltage, 2200 uF, 25 mm high.

FC-series equivalents (not quite so good a set of ratings) are EEU-FC0J152 and EEU-FC0J222.

Don't you just love having to suffer the consequences of somebody else's incompetent industrial espionage?

Eh? If it was incompetent, then I'd think the epsionage would be unsuccessful. Maybe I'm clueless as to what you're referring to. In any case, nowadays, it's common for the MoBo to be replaced before any of the parts die.

AE6EO

Yes, about 5 mm. Can't tell 5 mm from 5.08 mm with a ruler.

Thanks.

Loving every minute of it. And there's more to come since there are at least a dozen more capacitors of the same manufacturer on that board.

Over the past few years, a whole bunch of motherboards, and other industrial and consumer-electronics devices, have died a premature death due to capacitor bloating and leakage. The lifetime of the caps involved seems to have been on the order of 1-3 years, depending on temperature and load - sometimes as little as six months. This is seriously annoying for motherboards (not everybody wants to replace 'em after a year or two) and really annoying for network hubs/switches, 802.11 access points (both of my original-model Apple Airport base stations quit due to this problem), etc.

The cause was incompetent industrial espionage. As I understand the story, somebody who had worked for a major capacitor manufacturer (in Japan) stole the formula for his employer's new capacitor electrolyte formulation, and sold it to competing manufacturers in Taiwan and China. The formula "as sold" (and possibly "as stolen") was incomplete... it didn't include some of the stability additives. Caps made with the incomplete electrolyte tend to self-destruct - the electrolyte begins outgassing, the caps swell up and go high-ESR and sometimes leak.