Duorx With Rgb Amp Black Screen

[RyleFury]

Hello, i have a problem with the The RGB Amp for DuoRX. When I start the console, black screen, just the sound functions.
I used this rgb amp there :
http://www.gamesx.com/grafx/pce_rgb.jpg
I represented a printed circuit :
http://www.ifrance.com/rylelafurie/rgb%20amp.jpg
When I attach the signals directly, that functions but that made a dark screen.
From where the problem comes ?
My english is bad, sorry.
Thanks.

[Endymion]

The circuit that gamesx.com has had printed for quite some time now, I have read, is a bit questionable, although some don't mind putting it together for the results it provides.

You might read here for an easy amplifier alternative using the Sony CXA1145 chip. If you have an old Sega Mega Drive you do not otherwise need, then you can get to work. You might find this is an easier amplifier to work with, many have found it gives great results.

[RyleFury]

Thank you, am i obliged to connect sync composite at the pin10 ? Because i want to preserve the original video composite of the DuoRX. There is no out for the c-sync, but it however should be taken along to the av pinout ?

[Endymion]

Hopefully RARusk will see this shortly, but yes, I do believe you will need sync to pin 10. All you need to do is split this before attaching it to the CXA chip.

The link to the CXA1145.pdf in the thread above is dead, here is another location, get it while you can. Good luck.

[NFG]

The circuit in question, Endymion, is not the original crappy one but an all new fantastic circuit which I guarantee is fantastic, 'cause it's fantastic.  It's straight out of an old PC Engine book.

[Endymion]

Hm, in that case nevermind the questionable results bit.

The CXA still looks to me to be easier to set up though, if you don't mind sacrificing an old Sega unit that is.

Wasn't someone here using the CXA1645 to get both RGB and S-video from the PC Engine also?

[RyleFury]

The RGB Amp of the site :
http://www.gamesx.com/grafx/pce_rgb.jpg
It should works, is it ?
I forgot to say that I did not amplify the c-sync, I preserved c-video origin.

[RARusk]

Hopefully RARusk will see this shortly, but yes, I do believe you will need sync to pin 10. All you need to do is split this before attaching it to the CXA chip.

Yes, you do need a sync signal for pin 10 on the CXA chip. You can just split the sync into two lines, one for the chip and one for the monitor.

I don't get out here much nowadays. "Grand Theft Auto: San Andreas" and writing a guide for it has occupied most of my time recently. I actually had to go inside my RGB box and disable my amplifier setup. Whenever I put on the Thermal Goggles in San Andreas the picture would get messed up. This was because the screen was exclusively red and blues and the amplifier would really oversatuate the screen. I did put a CXA amplifier setup in my Nintendo 64 so I might not even need the one in the RGB box.

The PC Engine amplifier looks interesting. I may give it a try. Hopefully this will work as good or even better than the CXA setup. At least you won't have to sacrifice game consoles for parts....

[RyleFury]

Ok, thank you  
I can send the sync signal at the CXA chip and to preserve the comp signal for the monitor ?
Does somebody have an idea for my problem ?    

[NFG]

Unfortunately since the amp works for others (me!) I'd have to suggest you've simply done it wrong.  Check your wiring a few times, and then check it again.  Something's miswired for sure.

[Shimarisu]

He's probably not done it wrong, I regret to inform that for reasons unknown, the amp gives a black picture on a minority of TVs.

I've known about this amp for years, UK shops have been selling them inside SCART cables since the early 90s, and I've had many sent to me for repair. There seems to be little I can do about the fact it would not work on the customer's TV, or my Daewoo, though it works on most. because of this, I don't do the amp myself. I put the consoles in RGB by replacing the DIN socket to an 8 pin one, then refer the customer to a more expensive competitor for the amp. I'm not dealing with the mess of returns that result from selling amps to people with the few TVs they mysteriously don't work on. If there was anything I could do to fix'it I'd do research, but the fact I no longer live in england and test my conversions on a monitor I converted to SCART, means I have no access to a SCART TV any more.

And weirdly enough, the picture on my monitor is perfect WITHOUT the amp. It's a converted Joytech Gamecube screen.  

[NFG]

A lot of TVs with tuners in them require composite video instead of composite sync.  I don't know why this is, but I have heard some won't display a picture without getting a proper video signal on the sync line.

[Shimarisu]

A lot of TVs with tuners in them require composite video instead of composite sync.  I don't know why this is, but I have heard some won't display a picture without getting a proper video signal on the sync line.

That's nothing to do with the amp, as I always wire up to composite video.

If you don't have the sync connected right, what you tend to get is a rolling, hecticly jerking picture, as opposed to a black screen.

Trust me on the RGB in some TVs being weird. Sometimes the picture is really bad in RGB, my first TV was way too bright with ANY console, and the red was horrendously over pronounced.  

[D-Lite]

Hm, in that case nevermind the questionable results bit.

The CXA still looks to me to be easier to set up though, if you don't mind sacrificing an old Sega unit that is.

Wasn't someone here using the CXA1645 to get both RGB and S-video from the PC Engine also?

I think you remember all my posts about it.  Matt Ross also had helped on that.  But yes, I built an S-Video circuit from a CXA1645, and also used that for RGB amp too.  Worked great.