bally as-2518-54 ps voltage tolerance

TheShanMan

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My 6.3v supply was bad (it was about 3.6v) so I replaced BR1 and now it's running around 7.2-7.3. Is that within tolerance? I don't want it to run too hot if it will cause a problem.

Also, the BR I got isn't as tall as the original. It's the one below from great plains (gbpc3504w). In order for it to make proper contact with the heat sink I just left a gap between the BR and the PCB. Does that sound ok? Or do I have the wrong part?

GBPCW.gif


FWIW this is running in a mr+mrs pacman.
 
I don't know about the tolerance, but the bridge gap to PCB is fine, it allows for better airflow anyhow. I know the bridges on the main boards are gapped off the PCB so it should be fine.

The voltage is unregulated at that point....7.3 will be fine. Now, the gap on the bridge....I'm gonna have to disagree with you on that. I think the gap is a bad idea and will contribute to premature failure of the new bridge. The screw/plate turn the entire metal frame into a giant heat sink. With the new bridge not tight on the screw/plate...means the heat can't dissipate as designed.....meaning the bridge will run substantially hotter than normal. Those things were already running at about their maximum.


Edit: Nevermind (and sorry tomdotcom). I just re-read the first post. I thought the "gap" was between the bridge and the heat sink...not the bridge and the PCB. I agree with tomdotcom....it should be fine.
Edward
 
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I usually give about 10% tolerance on bridges since it varies with line voltage. Your line voltage may be higher then 120 giving you slightly higher readings. More then likely your voltage is good.

Is the voltage your measuring unloaded? Where are you measuring it? I believe there is also a 25 ohm power resistor that goes across the bridge, you should ensure that is indeed 25 ohms.

BR1 is a very stressed part of this power supply. Ensuring that all you header pins and connector pins are not burnt or browned and also be sure to use thermal grease between the bridge and the heat sink, it helps a lot to transfer the heat.
 
Thanks guys.

I measured it loaded using the test points on the board. I also measured the resistor at roughly 25 ohms as well.

I'm definitely using thermal grease when I reinstall.
 
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