Dreamcast to New Astro City: turning off the power supply

[TalkingOctopus]

I'd like to hook up my dreamcast to my recently acquired new astro city.  I think I understand everything I need to do except for one detail:  The power supply. 

I assume that when I'm using the dreamcast, I don't want the cabinet power supply to be active.  However, obviously I still want the monitor to be powered.  There are 2 power switches on the cabinet.  The main power switch is on back.  There is a secondary switch inside on the power supply unit.  I'm not exactly sure what the secondary power switch does.  From the manual:

This is a SUB POWER SW.  The AC unit on the rear part of the cabinet has the Main Power Supply SW (normally set to ON)

I'm thinking that when I hook up the dreamcast, I want to have the main power switch on and the secondary one off.  Does this sound right or am I totally crazy?  Do I actually need to physically detach the power supply wires to prevent it from running.

Thanks!

[Dave_K.]

I remember posting this exact question a couple years ago.  The Astro monitor will not turn on unless both switches are ON.

The advice I got was to either risk running the PS with no load on the +5, or put an LED or bulb across it.  What I ended up doing was just use the DC in my exceleena cab with upgraded tri-res monitor (it has its own 3-prong plug so I can keep the PS off no problem).

[TalkingOctopus]

I looked at the wiring diagrams and you're right, the monitor is connected to the power supply.  Argh...that means the two seperate switches are pretty much worthless.  I'd still like to try to get the monitor to run without the power supply.  I propsed my plan in a new post in the monitor forum.

http://forum.arcadecontrols.com/index.php?topic=58235.0

Thanks!

[Dave_K.]

Just replied to your thead over there, its not as simple as that, you will need an isolation transformer if you want to power your monitor independantly of the Astro power supply.

I still think loading the +5 on your DC Jamma setup is the simplest solution.

[TalkingOctopus]

Just replied to your thead over there, its not as simple as that, you will need an isolation transformer if you want to power your monitor independantly of the Astro power supply.

I still think loading the +5 on your DC Jamma setup is the simplest solution.

Thanks for the reply.  It looks like that's what I'll be doing.

Now for some dumb questions about loading the +5.  (You can probably tell I know little about electronics).

1)  Do you know of a place to get these tiny bulbs or LEDs?  Radio Shack?  A hardware store?  Fry's? 

2)  To load the +5, I connect the light to the +5 wire and the ground wire going to the jamma connector, right?  (Yes, I did just ask this.  I want to make sure I don't ruin anything). 

3)  Since the power supply is now on, does this mean I can use the Astro's sound amp?  It seems like I should be able to now.

[Dave_K.]

I take no responsibility if you fry your PSU, fry your DC, or kill your cat standing near-by.

1) radio shack has part # 276-209 that looks to handle 2v to 12v
2) the longer leg of the LED goes to the +5, shorter leg goes to ground
3) the Astro does not have a sound amp, sound comes from the Jamma PCB, and is routed to a sound knob on the PSU that then connects to the speakers.  If you have an MGCD board for your DC, the sound amp is on the PCB with a small potentiometer which is the primary sound control.  If you have a homemade DC to Jamma setup, you will need a sound amp to power the cabs' 8ohm speakers (search for SA-155 on ebay) and either connect the left (mono) side through the Jamma harness, or run your own wires directly to the speakers for stereo goodness (you can probably hack the molex connector to make this easier).

[TalkingOctopus]

Thanks a lot, Dave.  I really appreciate your help.  Of course I'm not going to blame you if anything goes wrong and fortunately I don't have a cat to sacrifice!

LAST BATCH OF QUESTIONS (I hope)

I noticed in the console section of the main page you recommended the SA-155 when I tried research this earlier. You state that:

you will NOT be able to use the existing 8 or 6 ohm speakers in your cabinet with a cheap PC speaker amp. [trust me it will sound horrible]. 

Except I did this with the arcade I built.  I think it sounds fine (or perhaps I am totally deaf).  I used the 8 OHM, 12 Watt 4" shielded speaker that Happ sells, (#49-0228-00).  I followed the tutorial on Oscar Controls (http://www.oscarcontrols.com/speaker/index.shtml). 

Could you clarifiy this recommendation based on your experience?  Are the speakers in the astro somehow different than the ones I bought from Happ?

[Dave_K.]

Good question TO.  Powered PC Speakers are usualy 2 or 4 ohms each.  The amp driving those will have an impedance mismatch with a pair of 8 ohm speakers in your cab.  This will do two things: it will clip your audio frequency (maybe you won't notice?) making it sound more "tinny", and it will also overheat your amp quicker (shortening the life of the amp).  If you are fine with the sound (because the Astro Speakers are kinda small anyway) go for it, as it can be even cheaper than an SA-155.  If you want the best frequency response and longer life get the SA-155.

I did the $9 cheap powered PC speaker thing on a midway cab with 8ohm speakers.  Maybe it was this brand, I don't know, but it sounded like crap with almost no bass response.  Thats why I wrote that in the FAQ.

[TalkingOctopus]

I spent all day executing the plan.  It was rather exhausting, but it's complete now.  I got the dreamcast attached and working, as well a ps2 and a pc, thanks to ultimarc products.  I can also still attach the one JAMMA board I have.  Unfortuantely, the ps2 videocable doesn't output blue, but hopefully, I'll get a replacement. 

The LED pulses, which kind of surprised me.  Maybe 5v is barely enough to light it.  It said it accepted up to 12v.

I hacked a set of $15 powered PC speakers and attached the amp to the astro's speakers.  They sound fine to me.  The SA-155 seems to go for about $50-60 on ebay at the moment.

Now, I just have to rotate the monitor and wait for an Espgaluda II board to fall out of the sky.  Then I'll be in shmup heaven.  Thanks again!

[Dave_K.]

Glad its all working.  Does the LED still pulse when a Jamma board is connected?  If so, then it must be the LED.

[TalkingOctopus]

Glad its all working.  Does the LED still pulse when a Jamma board is connected?  If so, then it must be the LED.

Yeah it always pulses so I guess it's the LED.  I rotated the monitor today.  It was rather painful.  One of the nuts was stripped, (how on earth do you strip a nut?).   Anyway, I managed to remove the stripped nut after about 3 hours and finally got it rotated.  I plan on leaving it vertical so thankfully I won't be rotating it often.