Building a test-rig, suggestions and a question...

[Level42]

I'm currently working on a power supply to use as a "test" power supply. I used an old Condor (a Phoenix bootleg by Sidam) power supply that I got for free when I picked up a (also free !) G07 chassis in Germany (which is now happily running in my Centipede).

I had to do some changes on the original set-up on the supply. My goal is to get as many possible supplies that I could need. The old Atari and vectors boards often require pretty strange supply voltages.

I've bought the usual 78xx and 79xx voltage regulators (for positive and negative 5,12 and 15 volts). The most are of the CV type that can deliver 1,5A if cooled properly. I wondered though if that would be enough for the +5V range. I guess for all other voltages the current draw is less of an issue. What do you guys thing, will 1,5A be enough on the +5V for most boards ?

Also: I'm moutning the regulators on the metal case of the power sypply, which is of course grounded on the mains side. Stupid question, but is it OK to tie the ground to the common of the regulators ? (That would happen if I mounted the positive voltage regulators directly to the metal of the PSU.)

And I've seen some test-rig set-ups before here but can't find the threads, I'd love to see others' solutions.
 

[Level42]

The supply:


Very nice for a bootleg builder ! An almost identical supply is in my Asterock.

The screw terminals are used to by pass the power switch (for now).
The other set connects the mains wire.
The third set offers me a nice 120VAC because the transformer doubles as a isolation transformer which is great for monitors !!!



The basic schematic of this power supply can be find in the Condor manual here:
http://www.vernimark.com/arcade/archive/pdf/condor_manuale.pdf

I's all very basic, diodes for rectifying.


The dark area on the solder side shows that these diodes have become pretty hot in use:


So I decided to put in new diodes and raise them from the PCB to give them some more "air to breathe".
I also added two diodes at the open spots to the right to get -20VDC for which the board is already set-up. I also changed the orientation of the two diodes on the left plus the cap that is involved to get -15V instead of the double +15V that it was initially set-up for.


The output DC and AC voltages (supply puts out + and -20V, +and -15V DC and 14V, 10.5V and 6.3 V AC) were originally connected through an edge connector but I soldered wired to the extra veroboard that I'll be installing with the voltage regulators.


Here is what I will be adding. The veroboard will of course be cut to size once I mount it.
I will have to isolate the negative regulators of course, but I'm not sure if I can leave the positive regulators contacting the metal because that metal is directly connected to the mains ground.

[CheffoJeffo]

Cool idea!

[Level42]

Wow, this one is nice ! :
http://forum.arcadecontrols.com/index.php?topic=91479.0

Although I will be hooking up a Jamma harness, I'm not (in fact, not at all) aiming at testing Jamma boards since only 2 of my cabs are Jamma, but I will build adapters as needed. Because I choose some more voltages it's also possible to power the older boards, incl. AC voltages (I hope).

[BobA]

I think the 5 V and 12 V amps might be too low if you are limited to 1.5 amps

As a test rig you might want to look at the amperage on this list of arcade supplies for specific games. You can get by will less but it gives you a ball park for power being used.

http://www.happcontrols.com/powersupplies/powsup_xref.htm

[BobA]

Link to my jamma tester.

http://forum.arcadecontrols.com/index.php?topic=65777.0

[2600]

For reference, a Peter Chou PS is 12A or 15A.  1.5A is way too low.  You should also have some large Caps before and after those regulators.

[Level42]

The large caps are only required before the regulators and are already on top of the original PSU set-up.

The fact that Peter Chou (or any other switching power supply) _can_ output that much power doesn't mean that the old early 80's game boards draw that kind of power. I'm not going to connect things like Primal Rage boards on that test set-up.

I do believe the 1,5 Amp might be a bit low for some boards, I'll look into that.

[Level42]

(Almost) finished the PSU.

It's not a beauty, but it does it's job !


Another reason for using this instead of a switcher: some AC voltages at hand. Esp. the 6.3 VAC comes in handy for an evt. powering of a CRT heater.



Did I mention that it also doubles as an isolation transformer and also puts out 120VAC which is also very cool (and needed !) for monitor work.

Mmm, gotta clean off the sawdust next time before I take a pic

Anyway, still need a couple of terminals for the negative voltages:


Need a Jamma harness to connect now....already ordered....

[ChadTower]

Some AC is definitely a major plus when working with stuff like the Kee games... the b/w games tend to take in AC and rectify it right on the game board rather than let the power supply do it as the later games do.

[Level42]

And Pac and Galaxian

OK, I just connected my Asterock PCB and measured it's +5V power consumption and it was around 1.6 Amps, which is a bit above what the 78S05CV can deliver. It got pretty hot too of course.

So, I plan on using this schematic to increase the amperage to 5A.



My only question is if this will still keep the 5V stable enough for PCB's...

[BobA]

The power transistor boosts the output capacity of your 78xx regulator so it should provide good power to your PCBs that require a bit more juice. 

[channelmaniac]

The biggest problem with that type of power supply design is NO FAILSAFE!

In other words, if you short the output of the +5v... or you have a shorted components that draws way to much current, the transistor could short and you would have the full UNREGULATED DC voltage flowing through your board. This will fry multiple chips.

Also, check to make sure your diodes AND the transformer can handle 5A of current draw! You don't want diodes shorting out or transformers opening up.

RJ