Tapper hum noise - loudest during high-score enter screen - MCR switcher

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Tapper hum noise - loudest during high-score enter screen - MCR switcher

My Tapper has an audible hum all the time and the hum gets even louder during the high score initial enter screen. The Tapper has the MCR switcher thingee in it. Any ideas? It must be some sort of ground thing or could it be a board issue?
 
I have a working MCR power supply I picked up for my Domino Man project.

I can just unplug the cables from the new adapter and just plug it into the MCR power supply and that should be it, right?
 
The hum is from the switcher. To eliminate the hum 100% you need to switch back to an original power supply. You can reduce the hum by putting a capacitor from 12v to ground, but it won't eleminate it.

When you say put a capacitor from 12v to ground, do you literally mean place a cap across the two leads on the switcher? Short them together with the cap?

I have that MCR switcher thing in my Tapper. It's not just a straight switcher.
 
Hum

MCR hum is usually a combonation of many things depending on the severity. The most common cause is simple connection issues. At the board or at the medium power board. "Switcher thingy" The medium power supply in need of rebuilding is also a common one as well. Loose connections at the dual amp board are something to check.. It seems like as you fix these things one at a time The hum gets lesss amd less severe. The bad thing is. All MCRs seem to have a small hum even when everything is perfect.
 
Just so we are all talking about the same thing...

My Tapper currently has one of these installed with a switching power supply:

mcrpic.jpg


I also have a spare original MCR power supply. I think I will put that in the cab today and see if it fixes it.

I would rather leave the newer switcher in with the adapter since it will probably be more reliable in the long run. Can someone please clarify how the capacitor is installed from 12v to ground? Do I short the 12V to ground on the 12v and ground terminal screws on the switching powersupply with a cap?
 
I just unplugged the switcher adapter and switcher and plugged in an original MCR power supply and now the hum is gone.

SO, yeah... it was the switcher that was causing the hum. So, now I need to know how to get rid of the hum cause I'd rather use the switcher.
 
Hum

The hum will always be worse with the switcher. The capacitor trick only reduces the hum. It does not eleminate it. A rebuilt origional MCR power supply will last a lot longer than a newer swutching power supply. Stick with the origional PS and you will be happier in the long run.
 
I just unplugged the switcher adapter and switcher and plugged in an original MCR power supply and now the hum is gone.

SO, yeah... it was the switcher that was causing the hum. So, now I need to know how to get rid of the hum cause I'd rather use the switcher.

I have nothing against switchers. I run one on my pole position and its great.
Good luck though on getting it to work with no hum on the Tapper. I tried with my spy hunter and had the same problem. (two spy hunters actually.) Many people have run into this with MCR games. I don't recall anyone ever finding an answer. I even tried putting in a ground loop isolator and it didn't help.
 
if you have a spare atari big blue cap laying around, you can try hooking the + lead on it to +12v on the switcher, and the - lead to ground. That should at least help.
My pole positions have switchers in them along with non factory amplifiers. I ended up adding something similar to this to get them to quit humming (or to at least get the hum low enough that it can't be heard over the fan) -
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370270918010
 
if you have a spare atari big blue cap laying around, you can try hooking the + lead on it to +12v on the switcher, and the - lead to ground. That should at least help.
My pole positions have switchers in them along with non factory amplifiers. I ended up adding something similar to this to get them to quit humming (or to at least get the hum low enough that it can't be heard over the fan) -
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370270918010

Hey, I do happen to have a couple extra big blue caps. I'm having the same problem he was. But whoever hooked up my switcher didn't hook up a ground wire. They took the power from the monitor power cables and ran it over to the switcher. Any suggestions on the best place to hook up the ground from? Can I just run it to any nut that's connected to any of the ground straps that I see in there?
 
another thing you can do is put a 7812 12v regulator in line with the 12v wire between the switcher and the adapter board. that will help too, as your switcher is probably pumping out more than 12v. between that and the cap on the switcher, that eliminated the hum in my satan's hollow.
 
when i said ground, i meant dc ground, not earth ground. Run the negative terminal of the big blue to the dc ground on the switcher.

The 12v reg helped J's as well. That all depends on what voltage your switchers putting out. It's gotta be close to 13 before it'll help at all.
 
Cool, glad I asked. I'll try it. There's nothing hooked up to the switcher ground at all right now. Should there be?

Also, I'm still having intermittent static noises as well. I don't think they are related to the hum (which isn't that bad really).
 
Is there any way around hacking the harness to get power to the switcher? I know it's not a big deal, but figured I would ask first.

Sorry for the hijack.
.
 
Is there any way around hacking the harness to get power to the switcher? I know it's not a big deal, but figured I would ask first.

Sorry for the hijack.
.

It's ok. Someone else already interrupted with his sausage fetish.

Mine is tapped into the power going to power the monitor. But there's also a power outlet inside the game. Perhaps you could just plug in there but I'm not sure if it turns when you power down the game.
 
Perhaps you could just plug in there but I'm not sure if it turns when you power down the game.

That power plug stays live.....regardless if the machine is turned on or not.

Also, if ground is not connected at your switcher.....you won't got output power (well, you'll get output power.....it just won't go anywhere).

Edward
 
That power plug stays live.....regardless if the machine is turned on or not.

Also, if ground is not connected at your switcher.....you won't got output power (well, you'll get output power.....it just won't go anywhere).

Edward

Sorry I wasn't clear. The switcher has the DC ground connected. It doesn't have the earth ground hooked up. The hum isn't that bad so I'm going to stop worrying about it. Why I have the other games on it's not noticeable. The static noise, on the other hand, sucks.
 
I fixed this hum issue on mine by pulling that switcher and installing an original power supply. It has been running perfect for well over a year now. Good stuff.
 
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