Shrill noise after playing my MVS for 15 minutes or more.

[Fygee]

Recently when playing my 4-slot Rev 3 MVS for about 15 minutes or so, I'll start hearing a shrill buzz coming from the speakers. Soon after the machine will reset, sometimes very rapidly. At this point I have to let it cool down to get it working again.

For the buzzing sound, I had a similar issue in the past where it was always present when playing, but disconnecting the card that powers the marquee lights resolved it.

For the resetting issue, I had to clean all the carts and contacts and that fixed it. I did so again this time with no change.

Any ideas what might be causing it? I inspected the boards and there's no popped or leaky caps, no corrosion, and the power supply looks to be okay (its one of those arcade ones with a semi-see through grill).

One thing that stuck out at me was this. I have no clue what it is, aside from it apparently being related to power. It looks pretty old and the top of it feels like crusty paper.

Normally when I see something with electronics that's bulging out that like, I get a red flag. Could this be related? If not, is this something I should be concerned with?

Any and all help would be appreciated.

 

[Tyranix95]

The part in your pic is called an Iso-Transformer.

And it powers the chassis.

When this part fails, monitor parts start going bad.

 

[Tyranix95]

The card that powers the marquee lights is called the EL Panel Power Inverter board.

Sometimes, the speakers humm when a back light starts to go bad. You'd have to cycle tough the El Panel display, watch the papers light up, and find out which one is causing the humm.

Othertimes, the inverter board is causing the humm. Don't know what the deal is here. Never came across this.

 

[Fygee]

Thanks! Do you believe that this may have something to do with my issue? I'm fairly ignorant when it comes to arcade parts, but to me the Iso-Transformer just looks...unhealthy. Then again I've never seen a new one so I'm not sure if that's the case.

 

[Tyranix95]

If the monitor is working fine, then no.

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But, since the board is resetting, I would get the multi-meter out and check the Voltage levels on the Switching Power supply (the other power supply in the cab). Make sure the +5v line is a 5.00v, and did not drift off course and go way above or way below 5.00v.

---

btw, what are the 4 carts on the board when it resets? Also, what happens when you try the board with just cart on the board? I've seen 4 Slots with a full deck of HI meg carts, reset, because they were not powered properly.

 

[Fygee]

When it started occuring, I had KOF '95, Puzzle Bobble, Samurai Shodown 2, and Fatal Fury 1. Fairly old, low meg carts.

However, with Metal Slug 3 and KOF '03 in it, it happens quite a bit faster and more frequently.

I'll try it with just one or two carts in it and see how it behaves.

 

[Tyranix95]

Running off the Jamma edge connector, the board can handle 4 Low~Med meg carts fine, or 2 Hi meg carts fine. So, you should be able to mix and match those cart combos with out issue. It's 3~4 Hi meg carts that can cause resets.

Post a pick of your power supply.

And find your multi-meter, and double check the +5v lines, with the games on the board, make sure the power levels have not drifted off course. The HI meg carts draw more power from the power supply.

 

[Tyranix95]

bwt, when you say "let it cool down," what part is getting hot?

 

[Fygee]

I don't own a multimeter as of yet. I'll pick one up and check it out.

There isn't any part that's getting hot, at least than I'm aware of. By that I meant I turn it off for about an hour and then turn it back on again, it behaves itself for a little bit. If I just do a quick power cycle the issues remain.

I'll get a pic of my power supply up shortly. I'm having some difficulty getting the grill off of the top of it.

 

[Xian Xi]

Even if it isn't the problem, get a new isolation transformer as they should be replaced every 20 years minimum as they usually have a life expectancy between 20-30 years depending on operating temp. If this is a dedicated 4 slot cab and it's been in there since 1991-93 then I'd say it's time to change it anyway.

 

[Fygee]

Cab was built in 1991, so its up there. How much do they cost? Any recommended place to buy them?

 

[RabbitTroop]

Cab was built in 1991, so its up there. How much do they cost? Any recommended place to buy them?

Happ isn't the cheapest, but I do go through them a lot since I can trust their products. They've got an Iso-Transformer for less than $25.

 

[RabbitTroop]

I definitely second checking the power supply as well. I've heard whining and seen resets before a PSU died on me. Those are also the most likely culprits of the, "was working yesterday, but not today," type problems.

 

[Fygee]

Thanks much RabbitTroop!

I'll be picking up the Transformer from the link you specified. Is there a power supply from there you would recommend as well, should mine be faulty? I parsed through some of the ones they have and while they look the same as the one I have, their wattage varies and Neo-Geo isn't listed as a component it's used for.

 

[RabbitTroop]

Thanks much RabbitTroop!

I'll be picking up the Transformer from the link you specified. Is there a power supply from there you would recommend as well, should mine be faulty? I parsed through some of the ones they have and while they look the same as the one I have, their wattage varies and Neo-Geo isn't listed as a component it's used for.

I replaced my Neo MVS PSU with this one last year, and it's been great. It should run anything you throw at it.

 

[thieslo]

Interesting about hte isolation transformers. I have heard of some of them lasting ages, and mine is definitely an old one.

However, some things to note, as far as a high pitched whine, the EL panels will make the high pitched wine when there is no load on them. Basically if your marquee panels don't light up then you are probably hearing the whine from the EL panel inverter. Easy way to check, disconnect the inverter from the motherboard (I think it is labeled something like MVS-EL or something. Just a small single connection. With that off, your marquees won't get power and the whine should go away.

Although this usually isnt something that happens after warming up, so i may have just sent you on a wild goose chase.

 

[Fygee]

I had actually disconnected the EL panel inverter when it originally give a non-stop whining sound after getting the machine (which sounds exactly the same as when it does now) and that worked.

I was hoping that would be enough to keep it happy, but I guess not.

I went ahead and bought the new isolation transformer and power supply. Even if the cause is not either of them, I'm sure it wouldn't hurt to have parts that aren't 23 years old in them. We'll see how it behaves.