What causes SMD caps to dry up or leak?

[shadow460]

I've got a second generation Game Gear which has all the original SMD caps inside. It's one owner and has been taken reasonable care of, although it's gone for up to a year without being played sometimes. The screen is a little faded and shows a few ghost lines in some games, but it's quite playable. The sound is crystal clear in both headphone channels and from the main speaker. It can be viewed from the standard 90 degree angle with no difficulty at all.

Now I've got a second Game Gear whose sound board had faulty SMD caps. This same problem also affect some NEC portables such as the Turbo Express.

 

I think it's something to do with how the consoles are handled or stored that's causing problems, or at least accelerating them. then again, maybe the one Game Gear just has a good run of caps, and the other one had a good run of caps on the mainboard.

 

Ideas? Or do I sound like a rambling moron?

Edited September 28, 2008 by shadow460

[channelmaniac]

I've got a second generation Game Gear which has all the original SMD caps inside. It's one owner and has been taken reasonable care of, although it's gone for up to a year without being played sometimes. The screen is a little faded and shows a few ghost lines in some games, but it's quite playable. The sound is crystal clear in both headphone channels and from the main speaker. It can be viewed from the standard 90 degree angle with no difficulty at all.

Now I've got a second Game Gear whose sound board had faulty SMD caps. This same problem also affect some NEC portables such as the Turbo Express.

 

I think it's something to do with how the consoles are handled or stored that's causing problems, or at least accelerating them. then again, maybe the one Game Gear just has a good run of caps, and the other one had a good run of caps on the mainboard.

 

Ideas? Or do I sound like a rambling moron?

 

The caps from that era suffer from leaking electrolyte problems. It'll corrode the board under the cap and cause all kinds of nastiness. clean the board the best you can and replace the caps.

 

Your game that is working is most likely just biding its time before dying. They all will eventually. Replace the caps.

[shadow460]

I'm just wondering what causes it. The working Game Gear has no evidence whatsoever of leakage. I just had it open a minute ago to ID the sound board caps so I could make a parts list.

 

Looks like I'm going to wind up repairing these things on a regular basis for folks whose systems are not working.

[+batari]

If it's the same situation as the bad PC motherboard caps, it's likely caused by bad electrolyte. Apparently an experimental electrolyte formula was stolen and used to produce countless millions of caps. The company from which the formula was stolen changed the formula and their caps don't have these problems. Regardless, even caps with a reliable electrolyte formula still fail, just not quickly and en masse like those with the pirate formula.

[channelmaniac]

If it's the same situation as the bad PC motherboard caps, it's likely caused by bad electrolyte. Apparently an experimental electrolyte formula was stolen and used to produce countless millions of caps. The company from which the formula was stolen changed the formula and their caps don't have these problems. Regardless, even caps with a reliable electrolyte formula still fail, just not quickly and en masse like those with the pirate formula.

 

Between that and faulty rubber plugs in the ends of the caps... or using underrated caps in high frequency or high voltage spiking circuits will lead to failure.

[gdement]

The stolen electrolyte thing didn't happen until many years after the Game Gear, and I doubt it uses caps of the size/type that were affected by that issue. But there's always been episodes of bad caps of one kind or another; the stolen electrolyte thing just being the most famous/notorious.

 

Judging from the caps in my Genesis (1989 build), it doesn't look like Sega worried much about capacitor brands. My Genesis has Chhsi in it, which are cheap junk. I've been thinking of replacing them in the hope it might help a video problem. I was ordering caps for something else recently and while I was at it I bought some Nichicons and Panasonics for the Genesis.

 

Heat and ripple (noisy power) both wear on caps. The difference between 1 Game Gear and the next might be the brand of caps they use. Do they look different at all?

It could also just be a difference of how much they were used.

[shadow460]

I think the units are a little different inside, but I'd have to look.