PC-engine RGB mod (amp) - left shifted picture

Started by sparriskrigaren, April 03, 2014, 02:15:49 PM

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Hello! I just finished an RGB mod for my PC-engine. I used an old schematic for an amplifier which is widely spread:

Since I'm using a Mega Drive 2 RGB scart cable, which is supposed to have 220 uF capacitors and 75 ohm resistors along the R, G, B lines I did not include them on my amplifier, and I have modified the schematics accordingly.

I have wired my cables according to the picture as well. I used a 330 ohm resistor in the sync circuit, not a 300 ohm one.

Everything works great, the picture and colors are nice but the image is shifted to the left with a black border to the right as a consequence:

Is this a common problem? Have I made an obvious mistake somewhere? Could it be that my cable does not in fact include the caps and resistors, and that adding them would help? From what I've gathered from googling, it's a sync issue (like, a delayed signal.. something).


An Extron RGB can give you horizontal and vertical adjustments, but you'd need SCART -> VGA+3.5mm audio; then BNC+audiocable -> SCART cable -> TV.

Is this a PAL signal on your PAL TV, or an NTSC signal?  If you don't play the other region, I'd consider opening up the chassis and adjusting horizontal position that way, or hire a CRT calibrator/serviceman to do it for you (high voltage and risk of death if you open it yourself and don't know what you are doing).

Or if you have a different input on the TV, perhaps it will be aligned better - you may be able to align for NTSC on 1 input and PAL on another, depending on your TV and if it can store settings per input.