PC Engine RGB Amp

PC Engine RGB Amp

This is out of date now, if/when I get another PC Engine I will try out an RGB mod using the THS7314 Amp, similar to the N64 RGB mod.

The RGB signal from a modded PC Engine can be too dark.  It’s simple to make an amp that will fit in the scart plug.  You only need 3 transistors, these are 2SC1815GR (could be called a number of things such as C1815GR or 2SC1815 GR etc, alternatives listed at the end of this page)

UPDATE

I just modded another PCE but decided to fit the amp in the console.  The following photo shows how I wired it up on the underside of the motherboard.  Or, you could solder it directly to the DIN socket.

Transistors and their legs

The three legs of the transistors used are as follows:

B – Base, this is the Video InputC – Collector, the 5v power supplyE – Emitter, this is the Video Ouput

Using a pair of needle nosed pliers, you can see how I’ve bent the input and output legs.

Bent input and output legs

Take 2 of the transistors and bend the middle leg outwards

Middle legs bent outwards

With the final transistor, just bent the middle leg to one side a bit – and test fitted it to a Scart plug.  We want the middle leg to goto Scart pin 8, and the output leg to go to Scart Pin 7.

Middle leg - pin 8, output leg - pin 7

It’s time to solder it into place, you can see I’ve shortened the transistor legs in the following photo, I’ve also tinned them (melted a small amount of solder to the transistor legs).

Getting ready to attach the transistors

Start with the transistor for Scart pin 15 (Red)

First one in place...

Now we need to add the second one to Scart pin 11 (Green), and line it up so that the middle legs line up exactly.  Once you have it soldered to the Scart plug, heat up the middle legs of the 2 transistors so that they join together

2nd one in place, and joined to the first one..

Now, we add the last resistor, we’ve already test fitted it earlier to make sure the legs were bent correctly.  Just make sure that you can solder the middle leg to the middle legs of the other transistors, without accidently joining it to any of the adjacent legs!  You can also see how I bent the end of the middle leg of the second transistor upwards (this is to solder the 5v wire onto).

Final one in place...and end of the middle legs bent upwards to solder 5v wire onto

That’s the amp complete, here’s how I added the 75 ohm resistor

Now you can solder the rest of the wires into place as per the RGB guide.

Just like the RGB guide, Saurian did supply me with a similar RGB amp, but I couldn’t get it to work, it looked like the Collector leg of the transistor was swapped with a Base leg so nothing would display on the screen.  All I’ve done is look up the Specification of the C1815 GR transistor and research what Base, Collector and Emitter meant, then arranged them to fit into a Scart plug!

Summary of Components

  • 3 x Transistors, I used C1815 GR, I have read that you can use C945 (or 2SC945, I don’t know why the 2S bit sometimes gets left off the part number!).  I’ve also seen here that you can use BC107, BC337 or BC546 (check which leg is E C B before soldering into place!)