Pong Transformer Output

[Guest]

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

I am restoring a pong and the transformer is shot. I want to verify
the outputs from the transformer. They are not listed on the wiring
diagram available online. I think they are +5 and -5 but I am not sure
which is which. Anyone have a pong that can check this for me?

Thanks
Dan

 

[Guest]

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

Dan,

The voltage from the transformer should be AC. It gets rectified
on-card and then regulated down to +5V by an LM309. The LM309 takes VDC
up to +35, so look for something 5V < X < 35V on pin 1. Keep in mind,
if there's something wrong with your board, and there's no current draw
from the transformer, you will not see voltage at the output of the
transformer! That doesn't necessarily mean the transformer is bad.

Also, IIRC pins 8 and 9 are +5V outputs from the card.

Good luck!

- Craig

 

[Guest]

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

Now I'm no electronics genius, but doesn't a transformer produce a
voltage on the secondary, whether its open-circuit or under load?

 

[Guest]

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

I don't believe so. I don't think an emf can be induced onto a coil
without current flow. Then again I can't explain why. Now you got me
second guessing myself! I'll look into it and get back to you if
no one else responds before then.

- Craig

 

[Guest]

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

I was wrong about this! Transformers do indeed yield an AC voltage on
the output even under no-load conditions. I tried it out on an iso
tonight, and sho nuff. Well that's one for the Yardbird errata page.
(one of many! lol)

- Craig

 

[Guest]

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

Craig,

The transformer is physically damaged so I am looking to find a
suitable replacement. Any ideas?

 

[Guest]

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

Dan,

Two things to worry about for finding a suitable replacement,
primary-to-secondary turns ratio, and KVA rating. The LM309 can take up
to 30V, but somewhere around 12VAC should be sufficient. So for the
turns ratio, if you're in the US and plugging the game into a ~120VAC
outlet, You need a turns ratio of about 10:1, where 10 is the primary
side and 1 is the secondary side.

Next the KVA rating, which indicates how much power it can output
safely. On the Pong board I have I'm measuring around 1.2A @ 5VDC. Call
it 2A @ 5VDC. Power = Voltage * Current, so you need a transformer that
can handle 10W. KVA is in kilowatts so you want one rated at 0.01KVA or
better.

Bob Roberts sells one that will do:

http://www.homearcade.org/BBBB/parts.html#ac
14VAC Xformer with 24VCT winding $10.00

Hope that helps!

- Craig

 

[Guest]

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

I have a bunch of early Atari transformers. If you have the part
number on the transformer I might be able to help you.

Otherwise you can check the schematic for the original output values
for the Xformer and use that to find a replacement - for example
hammon Transformers makes an enormous range of transformers and should
have at least one that would be close...

John :-#)#

On 24 Apr 2005 07:37:27 -0700, "danthepup" <danthepup@aol.com> wrote:

>I am restoring a pong and the transformer is shot. I want to verify
>the outputs from the transformer. They are not listed on the wiring
>diagram available online. I think they are +5 and -5 but I am not sure
>which is which. Anyone have a pong that can check this for me?
>
>Thanks
>Dan

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