PSU Schematic

[Trimoor]

Anyone have a schematic/circuit diagram for this power supply?
I can get it to switch the AC power, but no DC yet.

I can't find a model number, but the numbers on the transformer are as follows:

A037395-01Rev. A
142005-001
QK9-005RT-10
1W1ZP

Any ideas?

[Mameotron]

Wow, what does that thing power?

Just at first glance, I wonder if the round blue thing is a start capacitor.  They are known to go bad with age.  That should be easy to replace and they usually are $10 - $15.

[Trimoor]

It's made to switch the AC power for the marquee and monitor, DC for powering the game.

I don't think it's a "start" capacitor, as it's one of 3 main components: the incredivly heavy transformer, a full wave bridge rectifier, and the capacitor.

The resistance of the cap increases when voltage from my meter is applied, so I think it works.

[Ken Layton]

That is the power transformer assembly out of an Atari cabinet. Probably from a Dig Dug or Centipede.

[Apollo]

I guess you've checked the continuity of all the wires coming off the transformer?

[Mameotron]

(laughing) So much for my shooting off a post without thinking first!

It's been a while since my electronics classes, let's see if I remember this right...

The AC coming in is going to your transformer to step down to the 12V.  But some will just be taken off to supply the AC switches.  So the AC switches should work as long as you have continuity (which you do).

Coming out of your transformer you should still have AC, but a much smaller voltage.  It would be good to test and make sure the output from the transformer is what it should be, I'm guessing in the 12-15V range.  I don't know what voltage they would supply to the rectifier.

The bridge rectifier converts the AC to DC, so the output from that should be your 12V DC, although it will not be too smooth (stable).  A rectifier is just a bunch of diodes, but check to make sure they are all hooked up.

The capacitor is most likely used to smooth out the 12V output from the rectifier.

I would carefully guess that the transformer is the culprit.  (Is that green stuff on the transformer corrosion?)  It may still be working, but a tap could have broken off, or a turn (many turns?) in the coil could have shorted somewhere.  Unfortunately the transformer is the most expensive part of the power supply.

Sorry if you already know all this, I'm not trying to point out the obvious.

[RayB]

That's an Atari power supply, used in ALL their early games (with slight variations, though they all seem pretty much identical, especially in the '79-82 years).

These work in conjunction with a seperate circuit board called the "Regulator/Audio", though it's commonly called the "AR-II" since model II is the version found in the classic games (and even then, it had several revisions too!)

That PSU probably outputs around 36AC (if memory serves me right) to the AR-II. The Regulator board then converts it to DC voltages (+-12, +-5) for the game PCB.

I may be wrong though. Maybe it receives 36AC AND also some lower DC voltages...

Anyways. Seems like just buying a cheap modern switching power supply would be more reliable and easier to use than that big old thing.


~Ray

[RayB]

PS: Another thing to note: See that little bunch of yellow wires plugged in the middle? You're supposed to have 4 of those, each with different colors. Each plug was for a specific voltage range (for example, if you were in England, you would use the plug for the England voltage)

The reason I bring this up is that you need to make sure that's the correct plug. (if the whole thing came out of a working machine in North america and you're also in north america, then you're fine).

~RB

[Trimoor]

I got it in north america and plan to use it here, but i'd like schematics to check the yellow plug thingy.
Depending how it is wired, it connects one of several primaries in the transformer.

What confuses me is the number of output pins.  it only has one bridge and one cap, so how could it output different voltages? (if it does)

I found it in a jamma cab with no daughter board, so I would think it does multiple voltages.

I'm not sure how to check the continuity, since there are several pairs of secondaries on the transformer. (hence the numerous fuses)

The only reason I'm still using it is because it has nice connections for the safety switches. (right now, I use an old PC PSU for the game board, but I'd like to move this to another game.)

[RayB]

Do you have ANY idea what cab that used to be? Got pics?

That will help look up schematics. I could look up Missile Command and Centipede schematics for you, but I wouldn't want to end up being wrong (in case they did in fact do variations on the PSU from game to game).

Wouldn't surprise me if it only had one output, since as i said, the Regulator board converted and outputted the other voltages for the PCB. Are you sure there isn't another PSU in there? Maybe this one is only powering the monitor?

[Trimoor]

Someone said that the cab was originally a tempest, but it was a junked twin eagle jamma when I found it.
I don't think it was actually connected when I got it.

The pic from klov looks just like it:


Send me any schematics you think might work.
I should be able to figure out which type it is, I'm pretty good with electronics.

Why would they have nearly a dozen output pins, each connected to different wires, if it was only one voltage?

The monitor has its own internal power circuit, plus external isolation xformer.