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Ms Pac Man - placement of Yellow coated ground strap

Last response: in Video Games
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August 3, 2005 3:24:50 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hi all,

Trying to resolve that "wavy problem"
so I want to nail down all the grounds.

One of the yellow coated ground straps
is not connected. It's the one on the smaller transformer
(the one towards the front of the cab - the one not
connected to the fuses)

The other strap that is connected to the larger transformer
is connected to the game board.

Does anyone know where this other one is supposed to go?

Thanks

Mike
Anonymous
August 3, 2005 4:35:07 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

If you've got a recurring wave on your monitor- passing from right to
left, it's a 60hz "hum bar" and is typically caused by the cheap-o fuse
holders in the base of the cabinet. The other cause is a weak and / or
dirty edge connector at the game board.

Radio Shack sells good fuse holders, you'll need a pair of their 4
block sets, and you can cut off the unused holders. Solder each wire
one at a time and verify the fuse ratings while you're at it. It's
also a good idea to go ahead and install new fuses in case the
originals have corrosion. That will fix your hum bar the majority of
the time.

As for the edge connector, if needed you can clean it with alcohol and
a scotch brite pad, I have on occasion gently adjusted the inner wipers
on the edge connector with a dental tool, but bending too far will
unseat them and lead to shorts from the solder side to the component
side- so tread lightly.

For the finishing touch, you could install one of my 96 in 1 Multi-Pacs
:-)

http://home.everestkc.net/mdoyle/multipac.htm

Mike Doyle
Anonymous
August 3, 2005 5:15:36 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

On 3 Aug 2005 11:24:50 -0700, "Mike" <pinbuoy@comcast.net> wrote:

>Hi all,
>
>Trying to resolve that "wavy problem"
>so I want to nail down all the grounds.
>
>One of the yellow coated ground straps
>is not connected. It's the one on the smaller transformer
>(the one towards the front of the cab - the one not
>connected to the fuses)
>
>The other strap that is connected to the larger transformer
>is connected to the game board.
>
>Does anyone know where this other one is supposed to go?

As long as you tie all of them are tied together you should be OK.
Basically, they all end up back at the ground (Center round) lug
at the wall plug.

Best,

- Mike -
>
>Thanks
>
>Mike
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Anonymous
August 3, 2005 7:47:17 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

Mike wrote:
> Hi all,
>
> Trying to resolve that "wavy problem"
> so I want to nail down all the grounds.
>

Some people recommend replacing the fuse block / fuses. But I have found
that bad edge connector contact comes up at least as often if not more
as the cause of the hum. Sometimes the contacts within the connector
get loose and do not make good contact with the board. Other times the
contacts are slightly misaligned by a few mm and they interfere with
adjacent contacts.

Matt
Anonymous
August 3, 2005 8:12:51 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

I find that it's usually not the edge connector on the board itself, but the
black molex. The pins wear down over time and don't have the spring they
used to and they tend to corrode much like anything else. It's a pain in
the ass to swap them out but it's well worth the trouble. If you decide to
swap it just do it one pin at a time, don't sever the whole old one and then
try to use the color coding on it, it can be troublesome. Bob Roberts sells
a little kit with a new Molex and the fuse holders in one baggie.

Scott

www.agelessarcade.com


"Matthew DeSantis" <md4l@andrew.cmu.edu> wrote in message
news:D cr705$c63$1@usenet02.sei.cmu.edu...
> Mike wrote:
>> Hi all,
>>
>> Trying to resolve that "wavy problem"
>> so I want to nail down all the grounds.
>>
>
> Some people recommend replacing the fuse block / fuses. But I have found
> that bad edge connector contact comes up at least as often if not more
> as the cause of the hum. Sometimes the contacts within the connector
> get loose and do not make good contact with the board. Other times the
> contacts are slightly misaligned by a few mm and they interfere with
> adjacent contacts.
>
> Matt
Anonymous
August 3, 2005 9:29:49 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

If you're going that distance, you may as well install a switching power
supply as long as you don't mind not being original. Bob Roberts has a nice
adapter arrangement so you don't have to hack your cabinet and can restore
it back to the original transformer arrangement although I wouldn't
understand why you'd want to do that. You will be rid of the wavy lines
forever and can unsolder that ugly yellow strap.

If you decide to stay with the original transformer and fuse block
arrangement, you MUST change the molex connector pins (on the power contacts
at least) when you replace the fuse block. As the original contacts weaken
and and make poorer and poorer contact with the board, the contact starts
acting like a resistor and heats up. How many poor pac boards have you seen
with the A B/1 2 wide contact charred? I've repaired so many I've lost
count. If you use the switcher, it is more forgiving of the higher
resistance of the contacts as you are delivering less current to the board
through the contacts to begin with and won't have the heat buildup.

Best Regards,

Bill


"thrushguy" <garons@comcast.net> wrote in message
news:F9idndJ_QNzYuGzfRVn-2g@comcast.com...
> I find that it's usually not the edge connector on the board itself, but
the
> black molex. The pins wear down over time and don't have the spring they
> used to and they tend to corrode much like anything else. It's a pain in
> the ass to swap them out but it's well worth the trouble. If you decide
to
> swap it just do it one pin at a time, don't sever the whole old one and
then
> try to use the color coding on it, it can be troublesome. Bob Roberts
sells
> a little kit with a new Molex and the fuse holders in one baggie.
>
> Scott
>
> www.agelessarcade.com
>
>
> "Matthew DeSantis" <md4l@andrew.cmu.edu> wrote in message
> news:D cr705$c63$1@usenet02.sei.cmu.edu...
> > Mike wrote:
> >> Hi all,
> >>
> >> Trying to resolve that "wavy problem"
> >> so I want to nail down all the grounds.
> >>
> >
> > Some people recommend replacing the fuse block / fuses. But I have found
> > that bad edge connector contact comes up at least as often if not more
> > as the cause of the hum. Sometimes the contacts within the connector
> > get loose and do not make good contact with the board. Other times the
> > contacts are slightly misaligned by a few mm and they interfere with
> > adjacent contacts.
> >
> > Matt
>
>
!