replacing a monitor for a tv - electronical question

[ckong]

Hi Guys, I am replacing the original monitor in my Pac-man by a (Sony) TV. I made a scart adapter to connect the TV and it is working great, beautiful picture, much better than the picture from the original monitor and RGE worthy  . I made a bridge in the adapter from pin 20 (sync) to pin 16 (5V) which also works good. Unfortunately the TV doesn't 'boot' automatically into the RGB signal that it receives, so I need 12V on pin 8.  I am using a simple switching PSU for that. So far so good.

But I don't want to use the PSU, preferably I will take 12V from the game PCB connector, but that one spits out AC and I need DC. I am not going to build a 'gelijkrichter' schematic to get DC input, too complicated for me. So I was thinking of using a very common adapter, the ones that you use with laptops, handy's etc. I have one that runs on 110V (most of these adapters do), and outputs 12V DC, 2A. three questions from an electronics noob:

1. is 2A enough?
2. if I cut the plug from the adapter, does it then make any difference which wire goes were (to pin 8 and a ground pin)?
3. Can I just hook up the adapter to a 110V source in the cabinet?

If this works, then other cabs get the same treatment (I love it that you can nowadays get CRT TV's for 5€, or a sixpack beer   ). I would like to use a TV also in Gyruss, but I noticed that the TV's have a much longer neck then the monitor that is in Qix, it will not fit unfortunately and I have to find another solution.

[Etienne MacGyver]

preferably I will take 12V from the game PCB connector, but that one spits out AC and I need DC. I am not going to build a 'gelijkrichter' schematic to get DC input, too complicated for me.

Are you kidding me ?
thats one component...

i have one of these in my bin, i'll donate it to you 

[ckong]

Oh really?  I searched the net for info about it and I only found complicated schematics.

So,  that is very nice of you.  Can you mail it to me?  

[Etienne MacGyver]

sure, will look for the thing tonight

or if you have 4 diodes on hand you can simply create one :





http://nl.wikipedia.org/wiki/Bruggelijkrichter

[PaulSwan]

You'll need a capacitor on the DC side and if you really want 12.0V a regulator as well.
Paul.

[Etienne MacGyver]

yes, thats true, but would it not be sufficient enough to trigger that scart imput ?

its worth a try iyam.

otherwise its still simple, i used this all the time for a simple 12 volt powersupply :



but your input needs to be more than 12 volts though, i think you need around 14 - 15 volts minimum on the AC side comming from your transformer.

i guess thats the case anyway, since the ac-dc converter is somewhere integrated in the pcb to get the 12v dc that the board needs (probably for the audio section).

thinking about that, perhaps you can "steal"  the 12 volts there on the board somehow..

anyway, ill send you the bridge rectifier, just give it a try, if it does not do the trick, you can always go for another solution.

[ckong]

Ah nice, a schematic! Just what I was not waiting for.      I will stick to the 'handy adapter'.  

So:

1. is 2A enough?
2. if I cut the plug from the adapter, does it then make any difference which wire goes were (to pin 8 and a ground pin)?
3. Can I just hook up the adapter to a 110V source in the cabinet?

[Etienne MacGyver]

1. is 2A enough?
2. if I cut the plug from the adapter, does it then make any difference which wire goes were (to pin 8 and a ground pin)?
3. Can I just hook up the adapter to a 110V source in the cabinet?

1. its just a trigger signal, so my guess its more than sufficient
2. yes, positive (+) to pin 8, negative (-) to the ground of the scart
3. if your adapter supports 110v. i think its not a problem, but does the TV not run on 230V ?

[ckong]

Yes, the TV runs on 230V.

[Etienne MacGyver]

Yes, the TV runs on 230V.

then any standard adapter that supplies 12 volts can be hooked up to that source

Just install a 3 slot "opbouw" wall socket like they did in zaccs (an i did in he minipong)
then you can plug in your 1. tv, 2. stepdown converter and 3 the adapter.

[level42]

Trinitron in an arcade machine ? epic fail !

[level42]

Apart from that you guys are thinking WAY too complicated.

I had a TV in my Galaxian once. I didn't like it though. You don't have enough control over the position and size of the picture unless you use TVs like Bruno uses with menu set-up etc.

But it worked, the only thing I added was a voltage regulated 7812 to the Galaxian PCB I believe or was it a 7805....can't remember and I removed it before bringing my Galaxian to Thwocker because it now had one of the brand new WG monitors in there....

[level42]

Here you go buddy, had to dig up on BOYAC forum:

http://forum.arcadecontrols.com/index.php/topic,62784.160.html


Just one standard voltage regulator and some wire and connectors is all you need....

[Etienne MacGyver]

do still need to send that bridge rectifier ? , i think the mod like andre did is a much better solution..

(thats basicly the same as building a mini powersupply)

[ckong]

Apart from that you guys are thinking WAY too complicated.

I had a TV in my Galaxian once. I didn't like it though. You don't have enough control over the position and size of the picture unless you use TVs like Bruno uses with menu set-up etc.

But it worked, the only thing I added was a voltage regulated 7812 to the Galaxian PCB I believe or was it a 7805....can't remember and I removed it before bringing my Galaxian to Thwocker because it now had one of the brand new WG monitors in there....

The TV that I use has a menu with full picture control options. I hooked it up to the pac-man cab and got a beautiful picture. But now I am thinking about using it for Qix and install a NOS WG19K.. in the pac-man cab.