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mbarszcz-pcb / c64-rf-modulator-replacement

C64 Composite/S-Video RF Modulator Replacement
MIT License
80 stars 15 forks source link

Could this work on the C16 as well? #6

Open SukkoPera opened 2 years ago

SukkoPera commented 2 years ago

Hi, thanks for your project. I was wondering if this circuit could work in the Commodore 16, too. I am asking because I would like to integrate it in a clone mainboard I am making (with the obvious modifications for power, input signals, etc).

Here are the schematics of the C16/Plus4 modulator, taken from the Service Manual:

immagine

Your schematics look similar but not exactly the same. Do you think I could have a go with your circuit, which is a bit simpler and more tailorable (I like the pots!) or should I use the exact circuit from the above?

Thanks for your time! :)

SukkoPera commented 2 years ago

Same schematics as above with RF stuff removed. The similarity with this project is now more evident.

IMG_20211114_154751

SukkoPera commented 2 years ago

I have modified the schematics of this project adding the missing components and noting the different values of other components: image

Now, the 3 added caps and the added inductor are also present, with similar values, in the schematics of the 251696 modulator for the C64, which makes me think they aren't critical, if they were omitted from this project. This is also stated explicitly in this other C64 modulator replacement circuit I've found.

The rest of the circuit is exactly the same as this project's, with only a few different values. I don't have the knowledge to judge whether the different values are critical or not, but I think I can dare say that the circuit of this project will probably work on the C16 as well, possibly with a few different values for some components. I guess I'll go with it for the prototype of my boards. Once they are manufactured I will do some testing and report back.

Note that the current board of this project will NOT be a drop-in replacement for the C16, as the connecting pins are placed differently, some redesign will be needed.

mbarszcz-pcb commented 2 years ago

I'm sorry I am not familiar with the C16 enough to be able to judge whether it will work or not.

SukkoPera commented 2 years ago

No problem, we went ahead and ordered the boards. We'll soon find out :).