MVS power supply started buzzing (SOLVED)

I just made a pause switch for my 2 slot MVS. The switch works great, but after checking some things in the hardware test, I cycle the power and now there's a loud buzzing sound coming from the power supply, and there's some kind of blinking white or yellow light down there, isn't it supposed to be just red? Also, the P1 credit LED doesn't work anymore.

All the soldering and wiring for the switch is nice and neat, no shorts or anything anywhere. Oh, but here's one thing, that ring connector that grounds to the MVS board shielding, I dropped the screw down into the bottom of the cabinet, so I just wedged it inbetween the shield and the circuit board. I get 0 ohms between a random button ground and teh shield, so I figure it's a good connection.

I've also read that it could be that the fan in the power supply needs oiling. Should I be worried?

Is this a Big Red type 2 slot MVS cab or..?

Yes. MVS 2-25

I have never heard of a blinking white or yellow light in MVS-25 Power supplies,.. if it's the correct power supply...As it looks to me the light is red and can only turn red.
Are you sure that isn't sparks?

I hope that screw didn't fall into the Power supply...

"loud buzzing sound coming from the power supply", ............I had a power supply doing this in my big red(thin type peter chou PSU)and it was shot,the cab still ran but the power supply was causing problems.

I'd check the power supply,the fan may be gummed up,binding and overheating-causing the power supply to not work properly.
You could lube up the fan..

Note: when taking apart the MVS 25 Power supplies whatch how it goes back together as they can be a pain to get back together.

.........................................................................

Ultimate 150 Watt Power
Supply with External On/Off Cable




+5V 15A, +12V 5.5A, -5V 1A
UL and CSA recognized
External On/Off cable with 4-pin Molex
Dual AC input 115vac/230vac, selectable by switch
Low ripple and noise, EMI filter
Overload and short circuit protection
Built in DC fan and power switch
Metal case - XT size
Dimensions 8.74"L x 5.51"W x 4.65"H
Supplied with 8' long SJT power cord
Meets AMOA standard
1 year warranty

Unless it is a fan that has a hole labeled "OIL" you should never oil a fan.

Most computer fans are the type that are sealed and use brass non-lubicated type sleeve or ball bearings that don't need oil.

If you oil those types they will collect dust & junk and fail quicker.

Your best bet would be to replace the fan ASAP.

RJ

channelmaniac said:

Unless it is a fan that has a hole labeled "OIL" you should never oil a fan.

Most computer fans are the type that are sealed and use brass non-lubicated type sleeve or ball bearings that don't need oil.

If you oil those types they will collect dust & junk and fail quicker.

Your best bet would be to replace the fan ASAP.

RJ

Click to expand...

...Thank man..

I learn something everyday..

Okay, now that I've actually gotten in there and looked around, the buzzing isn't the power supply unit itself, it's the isolation transformer. When I disconnect the transformer from the PSU, there's no noise; the game and speakers function fine and naturally the monitor and marqee light don't work. Oh, and the flashing light is the LED on the switching supply flickering green/red.

Anyhow, I'm not too familiar with arcade electronics beyond controls, do you think simply switching out the transformer would help, or could this be a symptom of some problem within the monitor guts? Also, there was a screw, (not mine) the end of a zip tie, a toothpick, and a toothpick still in the little wrapper all laying around the transformer. Could this be a clue that somone's already tried to wedge a toothpick between the core and the winding? Or a hint that if it happens, the toothpick is already there for me to use, just in case?

What would you do?

thats funny, a toothpick? Maybey someone was just watching out for you when you heard this sound, its time to clean out your teeth? Im just kidding. If I were you, I would just simply replace the transformer, and maybey if still problems occur, get a new power supply. If you need a new power supply, I have an extra one sitting in my drawer that I could sell off, but check the transformer first. Also, if the bottom of your cab looks really dusty, you may want to clean it up a little bit indicating that there might be bad dirt inside of your power supply, and if so, that could strain upon problems to where the power supply cant function as well. I also have never heard of a blinking light... Wierd. maybey you have a wrong power supply? Well, I hope you can figure it out...

-idosk8

XYXZYZ


Can you take pics of the power supply --- isolation transformer and post them..

Certainly. Sorry about the image quality, either my camera sucks or I don't know how to use it.

Pictures removed/deleted from webspace]

The big Box,power supply in the center is the original power supply but it's dead..The Power supply to the right is the now working one(IMO they are crap)..and it's being ran through the old PS..

My 4 slot Big Red,2 Slot woody and 2 slot Big red all came like this..Luckily the person who put in the thin type PS didn't cut the Molex connectors to the cab,this way I just got the correct,original type PS and plugged it right in..

That thin type PS is probably going bad(the two I had in did)..One started buzzing.


This is the one you need.
http://www.happcontrols.com/powersupplies/80007200.htm

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http://www.neo-geo.com/forums/showthread.php?t=110156&highlight=slot+Power+Supply

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Oh yea,keep that Slot cover...They are not easy to find..

...waitaminute, let me get this straight- the presence of the switching supply tells you that the big supply must be dead, and the switching supply is starting to die, so the isolation transformer is buzzing? You're sure it's not the transformer itself?

XYXZYZ said:

...waitaminute, let me get this straight- the presence of the switching supply tells you that the big supply must be dead, and the switching supply is starting to die, so the isolation transformer is buzzing? You're sure it's not the transformer itself?

Click to expand...

No....

It's just that I've seen this switching supply into big supply combo three times ..
The switching supply is only ran through the big supply using it's AC(wall outlet power)
The Molex end(that goes up to the mobo 5+) on the big supply will be cut off of it and............ hooked up to the switching supply(as it is in your pic=red,yellow,black wires to switching supply)...The big supply may be still getting AC in power to run the Fan but it's not putting out any 12V,5V + to the Mobo..So it must be dead,(as mine were)


I may have some pics saved of how mine was set-up..Will try to post them later.

So, do you think it would be futile to run out and get another transformer?

XYXZYZ said:

So, do you think it would be futile to run out and get another transformer?

Click to expand...

Are you sure the Buzzing is coming from the transformer?.....Are you sure it's not resonating from the switching power supply..Or the fan on the big power supply.

futile to run out and get another transformer

Click to expand...

To be honest...I dunno..

I can't see why it would do that..
Buzzing I heard in Monitors and Power Supplies but isolation transformers I dunno(I don't know anything about isolation transformers-Sorry)

Me personally..I'd put in an original type power supply...


With a Buzzing isolation transformer I'm lost..


With the current two PS power supplies maybe a Ground is off or not located in the right place.

Okay, now I feel like an idiot. I was about to go out and get a replacement transformer, so I removed the existing one to bring along. But before I left I hooked it back up and ran it, started poking things. It turns out there was a tiny piece of film winding sticking out, resonating against the core! It was way down on the bottom, on the other side from looking into the cabinet from the back. So that's why I didn't get anything when I poked it when it was still secured to the wood. Snipped it off with a hobby knife, now everything's back to normal! I should have removed it and checked it from all angles in the beginning.

Thanks for all your help just the same Chris, maybe we both learned something here. I didn't know the main PSU was dead like that!

Now I'm off to enjoy my pausable Neo Geo.

Yep,I learn something everyday..Thanks..

Awesome!!!..Glad to Hear!!!