Removing the RF modulator on a C64 (PAL, 1983, W. Germany 251137, Rev B)

[Boojakascha]

Hello

 

The connection on the video out socket gets loose, so I think of putting a normal hosiden s-video plug into the chassis. Because there is not plenty of space I think of removing the RF modulator. However I am not sure as it is in this particular case as easy as in other micro computers as this one is HUGE. It is three times as big as the ones on ZX Spectrums and the like. Is it really solely a RF modulator, which I am allowed to remove, or does this thing more than that?

 

The alternative would be to the remove the video out socket and put a new in. I did that with my Atari STE. But it was cumbersome...

[mrr19121970]

I think if you remove the modulator then you will get no video out anymore. See the schematic. An alternative see http://www.breadbox64.com/blog/c64c-rf-box-mod/

[dgc79]

On 6/13/2017 at 11:38 PM, mrr19121970 said:

I think if you remove the modulator then you will get no video out anymore. See the schematic. An alternative see http://www.breadbox64.com/blog/c64c-rf-box-mod/

That is correct, no more video out - only sound out of the DIN A/V connector.

My modulator died, I replaced it with one I built myself which was based on the attached schematic that I found.

 

So I created a veroboard layout which replaced my modulator! I wanted it to be a normal commodore video output though because I use a 1084S monitor. I suppose you could changed it to S-Video output by changing some components. The one I show is only for shortboard c64c and above, not for longboard breadbox. Layout would be very different for breadbox.

 

The labels on the left-hand side of the board are pin headers (3rd pic) to mount it into the commodore. I put a small foam pad underneath the board so it rests on the c64e PCB, the pins hold it in place really well. The red dot on the vero layout is a cut track, the other cut track is underneath the diode.

 

This replacement works really well!

My chroma/luma picture on the 1084S is slightly better than it used to be i think!

Probably because it is not driving the RF circuitry anymore.

 

[Jack1956]

Thank you very much for the schematic.

I had exactly the same problem, the old modulator was causing checker-boarding on my C128.

When I carefully removed the modulator, it fell to pieces, the whole top layer of the pcb lifted and separated!

 

So I built the circuit on vero board, and it solved my video issues.  No more checkerboard, and much less vertical bars.

 

I'm now in the process of designing a PCB, for construction of the circuit using SMD's.

 

JP