commodore 64 CD4066

[ami_junki]

hi guys, my commodore 64 has a grey screen, no colour sadly, i looked up on the net it seems that i need to replace this thingy:

commodore 64 CD4066 (generic CMOS quad bilateral switch)

but i am having a real tough time finding one?

does anyone know where there is a good supplier of c64 chips?

cheers,
timo

[Speelgoedmannetje]

The newer commodore 64's are capable of outputting an s-video signal, which contains a line for colour, and a signal for intensity.
This intensity line gives a black and white picture. Maybe the colour line is broken?

[Zac67]

[digging out schematics]
The 4066 (U28) is just for multiplexing the paddle signals (two ports to a single SID port) and has no connection to video output. I've never had a problem in sourcing the chip (up to ~10 years ago) though. I've just checked and it's still widely available ("CMOS 4066 DIP").

If color is lacking from both RF output and DIN plug S-video output, I'd guess it's either the VIC or one of the Q4, Q5 or Q6 transistors (all PN2222)

If the problem is RF only the modulator needs to be replaced. I think I've got a PAL type somewhere, but would need to do some searching...

[countzero]

I hope you're not using a PAL machine on a NTSC tv.

[ami_junki]

thanks guys, i originally had a checkerboard screen in black and white then i bought a replacement vic II chip, now i get the home screen but just in black and white, it is ntsc machine as far as i know unfortunately as i am in japan i can`t try the rf signal on our japanese tv just the av cable

[Speelgoedmannetje]

AFAIK modern tellies can be (manually?) switched to NTSC.

[tone007]

What type of AV cable are you using?  Most of the original Commodore AV cables I've seen had seperate luminance and color signals, which doesn't work so well for modern TVs without an S-video adapter.

[ami_junki]

ahh maybe that is the problem, it is an un-official cable i bought on ebay, i guess i should really try it with an older tv

[Zac67]

If you need a composite style signal, use the chrominance part (pin 4 instead of 1) only - lacks a bit of contrast but is fine otherwise. However, if your TV supports s-video, connect both signals to get the best quality possible.

[Speelgoedmannetje]

Zac67 wrote:
If you need a composite style signal, use the chrominance part (pin 4 instead of 1) only - lacks a bit of contrast but is fine otherwise.

That simply won't work. However, if you join the chrominance and the luminance signals (just by soldering it together), you get composite video.

[Zac67]

It does work on the 64. I've been using it that way for ~8 years with a Philips monitor (1084 clone).