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Tech: Space invaders power board

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Anonymous
July 28, 2005 5:55:31 PM

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

The +12 volt regulator on both my space invaders, and space invaders deluxe,
is blown. The only one that has Identifiable markings is a 78M12c, and every
data sheet I find on it says its rated at a .5 amp output. All the
replacements I can find available to me are rated at a 1 amp output. is this
a problem? or should I just go ahead and pop the new ones in? I believe the
rest of the board is alright.
Anonymous
July 28, 2005 6:00:59 PM

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

It is absolutly, 100% acceptable. That part is simply "capable" of
yielding more current on demand without exceeding it's set operating
specs.

- Matt
Anonymous
July 28, 2005 11:18:24 PM

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

Hi, If you can post some of your findings and save me some leg work
too. I have a SI deluxe with a weak power supply. Barely gets +5v, and
just under 12v. The sound is very muted, and the sound board has alot
of sort of corrosion or dirt/ rust.

I would rather use this origional power supply other than a switcher.
thanks
Jay
Related resources
Anonymous
July 29, 2005 12:28:29 AM

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

Thanks for all that have replied. That's what I thought, but just wanted to
be 100%. Seems the whole 12 rail is out of whack. found 2 dead resistors
((36ohm and 270 ohm) right next to the 12v adjust pot, and I'm still only
able to get about 8 v at the test point.

Gonna be a busy night with this it seems.


"Matty-t" <matthews@audio-doctors.com> wrote in message
news:1122584459.353992.288610@g43g2000cwa.googlegroups.com...
> It is absolutly, 100% acceptable. That part is simply "capable" of
> yielding more current on demand without exceeding it's set operating
> specs.
>
> - Matt
>
Anonymous
July 29, 2005 1:59:01 AM

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

This site has been really helpful at sorting out proper test points.

http://www.elektronforge.com/tech_help.htm

The actual bad part tracing is up to you, but its a start. So far I've
replaced the two resistors on the right of the middle pot (the 12v rail),
the 12v regulator, and now I have a suspicion that the pot itself is a bit
tweaked.

Weird thing is, BOTH boards I have the same problem. I wonder if this is a
common thing.

<experimental208nd@comcast.net> wrote in message
news:1122603504.022645.109400@g43g2000cwa.googlegroups.com...
> Hi, If you can post some of your findings and save me some leg work
> too. I have a SI deluxe with a weak power supply. Barely gets +5v, and
> just under 12v. The sound is very muted, and the sound board has alot
> of sort of corrosion or dirt/ rust.
>
> I would rather use this origional power supply other than a switcher.
> thanks
> Jay
>
Anonymous
July 29, 2005 6:31:11 AM

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

A higher amperage rating on the replacement part is good. It will handle
twice the current load that the original would.

Mark Hooks

"Tony Tumminaro" <TonyTumminaro@comcast.net> wrote in message
news:F5qdnW4t9ogNt3TfRVn-1A@comcast.com...
> The +12 volt regulator on both my space invaders, and space invaders
> deluxe, is blown. The only one that has Identifiable markings is a 78M12c,
> and every data sheet I find on it says its rated at a .5 amp output. All
> the replacements I can find available to me are rated at a 1 amp output.
> is this a problem? or should I just go ahead and pop the new ones in? I
> believe the rest of the board is alright.
>
Anonymous
July 29, 2005 4:17:19 PM

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

> This site has been really helpful at sorting out proper test points.
> http://www.elektronforge.com/tech_help.htm

That's us!

> Weird thing is, BOTH boards I have the same problem. I wonder if this is a
> common thing.

Are you testing your power supplies with the motherboard and daughterboard
disconnected, or are they still attached? It's possible that there may be a short
on one of them that is dragging down your +12V line. If it jumps up to +12V
once when they are disconnected, then that might be what's happening...

Alex
----
ayeckley@elektronforge.com
www.elektronforge.com
Anonymous
July 29, 2005 4:17:20 PM

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

"Alex Yeckley" <ayeckley@elektronforge.com> wrote in message
news:j7pGe.486$dm1.22@newssvr31.news.prodigy.com...
>> This site has been really helpful at sorting out proper test points.
>> http://www.elektronforge.com/tech_help.htm
>
> That's us!

Great info. Thanks for that.

> Are you testing your power supplies with the motherboard and daughterboard
> disconnected, or are they still attached? It's possible that there may be
> a short
> on one of them that is dragging down your +12V line. If it jumps up to
> +12V
> once when they are disconnected, then that might be what's happening...

That does appear to be the case. After repairing both the power boards, it
appears that both my motherboards might have a similar short. Digging into
it further tonight. Thanks.
Anonymous
July 30, 2005 1:09:07 PM

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

I had this problem with my SI, measure across GND and +12 lines on each
board. Once you have the bad board Check those small blue ceramic caps. I
was lucky and found the bad one first time...right next to the 8080.
replaced it and the game was fine. Also had the same style cap go short on a
Congo Bongo sound board.
"Tony Tumminaro" <TonyTumminaro@comcast.net> wrote in message
news:QYKdnSGBoJwwpnffRVn-2g@comcast.com...
>
> "Alex Yeckley" <ayeckley@elektronforge.com> wrote in message
> news:j7pGe.486$dm1.22@newssvr31.news.prodigy.com...
>>> This site has been really helpful at sorting out proper test points.
>>> http://www.elektronforge.com/tech_help.htm
>>
>> That's us!
>
> Great info. Thanks for that.
>
>> Are you testing your power supplies with the motherboard and
>> daughterboard
>> disconnected, or are they still attached? It's possible that there may
>> be a short
>> on one of them that is dragging down your +12V line. If it jumps up to
>> +12V
>> once when they are disconnected, then that might be what's happening...
>
> That does appear to be the case. After repairing both the power boards, it
> appears that both my motherboards might have a similar short. Digging into
> it further tonight. Thanks.
>
!