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Main => Main Forum => Topic started by: Wir3d on March 14, 2006, 06:42:38 pm

Title: Humming noise coming from power supply
Post by: Wir3d on March 14, 2006, 06:42:38 pm

The humming noise only happens when the jamma harness is unplugged from the PCB.
its in a MK 2 cabinet btw....any solutions as to why this is happening? its more like a pig squealing noise.

Title: Re: Humming noise coming from power supply
Post by: Wir3d on March 14, 2006, 07:29:04 pm

My neutral (white) wire coming from my power cord is getting 120V and my black (hot) wire is reading 0 on my tester..could this be a problem?

Title: Re: Humming noise coming from power supply
Post by: SirPeale on March 14, 2006, 09:31:25 pm

Quote from: Wir3d on March 14, 2006, 07:29:04 pm

My neutral (white) wire coming from my power cord is getting 120V and my black (hot) wire is reading 0 on my tester..could this be a problem?

That's backwards.  White is hot, black is neutral.

No, you're hearing noise because you've taken the load off it.

Squealing from a PS isn't good in any event.  Likely it has bad caps.  I suggest either replacing it, or recapping it.

Title: Re: Humming noise coming from power supply
Post by: Wir3d on March 14, 2006, 10:38:56 pm

ok, thanks peale, and ive tested the voltage on the +5v -5v +12v and there all giving me a reading of about 1.8v when powered on, so i think the power supply is bad

Title: Re: Humming noise coming from power supply
Post by: Ken Layton on March 15, 2006, 02:06:17 am

You have a power supply that REQUIRES a load be connected to it at all times it's powered on. WARNING: it will be damaged if you leave it that way. Either unplug the AC power going into it or connect a gameboard to that power supply now.

Title: Re: Humming noise coming from power supply
Post by: Wir3d on March 15, 2006, 05:29:48 pm

my power supply was making the whining noise when it was connected to the board...i bought it from tnt amusements...it was used and i only paid $6 for it, its a peter chao....after i heard the whining noise i decided to disconnect the jamma harness and try it that way, but it made no difference.

Title: Re: Humming noise coming from power supply
Post by: Ken Layton on March 15, 2006, 06:42:33 pm

If it's a Peter Chou with screw terminals, then the whining noise is because it needs capacitors now (they are about to explode). Peter Chou with screw terminals are one of the few power supplies that can be run without a load connected.

Title: Re: Humming noise coming from power supply
Post by: Wir3d on March 15, 2006, 08:55:36 pm

yes it has screw terminals....the model number of the power supply is #F102141288....and what caps do i replace on it? all of them incuding the small ones or just the bigger ones?

Title: Re: Humming noise coming from power supply
Post by: SirPeale on March 15, 2006, 09:46:16 pm

If you open it you may see that they're bloated.  Those ones are obvious.

Generally, it's the larger caps that go.  If/when you replace them, replace them with hi-temp caps!