On 2012-07-08, at 17:20, Gerrit Heitsch wrote: >>>> https://dl.dropbox.com/u/58002657/C64_rf_modulator_replacement.png >>>> >>>> Any comments / striking errors in this? What should I put more attention to? >>> >>> I see you use pad 1 in this layout. At least on the 250466-Board this is the power supply for the modulator, but it's not +5V but unregulated +9V (usually a bit more). Same goes for a 250407 board. So you either need to add a 78(L)05 or grab the +5V from somewhere else. >> >> There is a pinhead for +5V to be used for the Y/C amp. That +9V is to be used (via jumper) to power the audio amp in case I like it and want more output ;-) > > Ok... Then keep in mind that on the 250469 boards (the ones with the 64pin 'PLA'), the modulator pinout is slightly different and it's powered with +5V. It's also smaller. The "narrow" boards you mean (I don't have the p/no at hand)? That will ask for a different version anyway. I'd like to check whether this helps on the older board first and foremost. One thing I am wondering is the impedance of the audio output from the board (eh, that analogue stuff). I assigned 10K Poti but have probably to check better, especially if I want to cross two channels over together. The schematics is here https://dl.dropbox.com/u/58002657/C64_rf_modulator_replacement_sch.png "BYPASS" elements are placeholders. -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-07-08 16:00:21
Archive generated by hypermail 2.2.0.
