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View Full Version : Drowning in a sea of Delta's...


#13
07-24-02, 01:17 PM
I'm rebuilding a case w/ an "ultimate air cooling system" sort of mentality, and have a secondary ps to handle all the fans. It's an old AT style, about 230W. My origanal worry was that it seemed to spike when it shut off -- the fan would "rev". Then I tested it w/ a voltmeter, so I wouldn't waste your time. I found that w/ a 92mm Delta, it would spike from 10.1v to about 10.5v (it's a cheap voltmeter and doesn't refresh very quickly, so it could be more). This doesn't seem to be a problem, since the Delta's are rated at better than 13v. But it's at 10v?! I tested a BIG Rotron, and it dropped to ~8.6v. W/ all the fans hooked up, I'd get like 2-3v's at best! (Unqualified estimate)

Now, I WAS planning to do a baybus type thing w/ the 7v mod, but it's clear that this ps isn't capable of supporting my insane need for more fans. I do have a 300w AT, but I've already butchered this ps. I don't want to just throw it away. So, any ideas on how I can use it? I thought about using two ps's, but I don't want to have two of those switches to deal w/. Can I put them both on one switch (I'm going to Radio Shack in about an hour, hint hint)? Can I modify the pcb itself by soldering or unsoldering things? I'll get more info on the fans and ps's if you need 'em. Thanks a lot for reading all the way to the end of the post!

#13
07-24-02, 07:23 PM
OK, forget all that. The problem (after a lot of twisting wires together) seems to be that this (old) ps requires a 5v load, but otherwise will run all the fans (before, on occasion, the fans wouldn't turn over). The voltages haven't changed much overall, but the fans seem to run more happily. The trouble is that the voltages aren't quite right (I'm picky), and I have to run SOMETHING at 5v all the time.

First the voltages: 12v=11.28v 5v=5.04v
This means that the 7v mod produces about 6.24v.this is fine for the 92's, alright for the 120's, but wastes the Rotron (~150mm). I think the Rotron would be happy at about 8-9v (the rest of the fans would be fine too). When I run it on "12v", the voltage drops to ~10.5v. That wouldn't be a problem, but it also drops the "7v" to ~5.5v. If I put a big load on the 5v, then (obviously) I get some of that back (I've had it up to 6.5v w/ no 12v load). If I could drop the 5v or increase the 12v, then it would be alright. Any suggestions?

I also need a 5v load ALL the time. As I stated earlier, the more 5v load I have, the more I'll get out of the 7v thing. So, should I get a bunch of 5v led's, or what?

THX.