This is what I use:
http://www.crescendo-systems.com/transcoder.htmlI use the TC1600 VGA to component transcoder (scroll down a bit), which is a little more expensive, but the TC1500 will also do the job very well. It just lacks some optional adjustments that most people will probably never use with game hardware.
A cheaper option than either of those, but one that still works very well, is a CVS-287 RGB SCART to component transcoder:
http://www.ebay.com/itm/NEW-SCART-RGB-to-YPbPr-Component-Video-Converter-Scaler-/370695549217?pt=US_Audio_Cables_Adapters&hash=item564f2d3121There are also transcoders available from RCA, Audio Authority, and JS technologies, but it hasn't been confirmed that these will work consistently with arcade resolutions, so they should be avoided. Other users have actually had a lot of problems with the RCA unit; the other two are just unconfirmed. I have personally tested the TC1500/1600 and the CVS-287 extensively and haven't found any problems.
Whichever one you use, find the red video, green video, blue video, composite sync, and ground lines coming off of your PCB. As I said, you'll probably need to run each (except ground) through a resistor or potentiometer to bring down their signal levels, so that the final picture on the TV isn't too bright. Next you have to connect these lines to a connector that you can plug into the transcoder.
The CVS-287 uses a SCART connection. So you'll need a SCART connector you can solder to. Look up the SCART pinout, and you'll find a diagram of what each pin does. Connect your red, green, blue, and sync lines to the appropriate pins. There will be several ground pins in the SCART pinout. Just tie them all together and connect your ground line to that. Ignore the rest of the pins.
The TC1500/1600 uses a VGA connection. So you'll need a VGA connector (DB-15HD) you can solder to. Look up the VGA pinout, and you'll find a diagram of what each pin does. Connect your red, green, and blue lines to the appropriate pins. You'll notice that the VGA pinout uses separate pins for horizontal and vertical sync, but most PCB's output composite sync, meaning the two are combined onto one line. The TC1500/TC1600 can use composite sync if you connect it to the horizontal sync pin. There will be several ground pins in the VGA pinout, just tie them all together and connect your ground line to that. Ignore the rest of the pins.
Then just connect the output of the transcoder to the TV with a standard component cable, and you're good to go.
Let me know if you need links to the parts you'll need.