C128 With Good RF Signal But Black Screen Through SCART

[Arranyn]

Hi all - this one is bugging me.

I have a PAL C128 that works perfectly and displays a solid signal to the TV through the RF socket.

When using a DIN to SCART cable I just get a black screen.

I’ve tried two separate cables, both of which work fine on my C64.

The 40/80 key is not down and the machine (through RF at least) looks to be working properly in C128 and C64 modes.

I’ve checked the video DIN socket and re-flowed the joints but still just a black screen through that socket.

Any suggestions?

[rmzalbar]

Well the video on the DIN connector is amplified and mixed in the RF modulator. Check the DIN traces, joints, and filtering components between DIN and modulator pins. If that's good then something may have failed in the RF modulator, even though it seems to be able to provide RF output. In particular there are output transistors that don't contribute to the RF output, only the DIN video.

I don't have enough experience with SCART: Does it handle separate luma/chroma if available, or would it only be using the composite? You would want to know this when tracing inward into the RF modulator.

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