Console2JAMMA quick Question

[Mr-Megalo]

Howdy peoples,

just a quick query to anyone who has hooked up a console to there JAMMA cabinets by tapping the RGB and converting the sync via LM1881 sync circuit, is there anyway to boost the signals so they are not as dim on screen ? I know you can always alter brightness/contrast settings etc but I'd prefer to not do this, I am playing with one monitor that even when the settings for RGB contrast/brightness are turned up, it still doesnt look quite right, and as standard it is really dark in comparison to JAMMA PCB's

talking of which - I know Andy@Ultimarc is selling an X-box to JAMMA kit, included is a Video amp, has anyone tried using the video amp with say a PS2 or Sega Saturn ?

any infos on either boosting the signals or using the video amp with other consoles would be greatly appreciated and welcomed very muchly

[Dave_K.]

Add 220uf caps to the RGB lines to brighten the picture for consoles.  Lawrence used to have this hint on his gamesx page, but I just checked and I don't see it anymore....probably due to numerous site redesigns.  Try to use non-polorized caps if you can find them...otherwise I'll have to check my circuit to see which way negative goes.

[Mr-Megalo]

thanks dave,

I posted this message on gamesx forum aswell, gamesx.com = essential website 

[Mr-Megalo]

Dave - on the thread that i posted on gamesx, it has been said that adding the caps will do nothing

/Mr-Megalo is confused 

have you tried this method yourself ?
I have to order these bits online (local store doesnt have them) and the P&P is going to be more than the caps themselves 

[Dave_K.]

Adding caps do not "amplify" the signal.  Thats why they don't know what you are talking about when you asked them how to amplify it.  The caps do brighten the picture (I don't know the technicalities of why).  This was posted on the same page as Lawrence's LM1881 circuit awhile ago.  If you can get Lawrence to respond, he will confirm it.

  I have them in my LM1881 circuit hooked up to an arcade monitor (for playstation2) and it looks fine.

You don't need huge 220uf caps, just find the smallest voltage you can.  Shouldn't be that expensive.

[Mr-Megalo]

well - Dave, your a kindred spirit so I'm gonna go with you on this and order a bag of caps,

Lawrence seems to have gone M.I.A so a BIG thanks to you
I'll post results once I've received them and added them to the RGB lines.

Off Topic - dont be surprised if my Aero Table ends up going to another home

[n3rrd]

Purely speculation, but caps are usually added to clear noise off of a line.  Maybe the board is getting "dirty" signals and averaging it out?  Iono.

[Dave_K.]

Mr-Megalo, any update?

[AlanS17]

I think ya'll got confused on a technicallity. You're using the word "brighten", but i think you mean "lighten".

Is the screen dim or dark?

[Mr-Megalo]

the screen conditions vary depending on cab/monitor that is used.

On my Astro 2 - the picture is clear enough but suffers from overbrightness (twiddling with brightness controls sorts this) on a black screen there is too much white/greyness like the contrast/brightness needs adjusting but on the Namco cab even with brightness/contrast at full the screen is too dark.

I haven't tried adding any 220uF caps as yet as I havent had the time to tinker with anyting for myself

[richardp171]

Adding caps do not "amplify" the signal.

[Mr-Megalo]

Paul,

http://www.mameworld.net/pc2jamma/arc_dc4.html

http://www.mameworld.net/pc2jamma/images/circuit1.gif