On 09/04/2011 06:31 PM, Segher Boessenkool wrote: >>>>>> After all, the 656x-VIC-II still needed +12V for parts of the chip >>>>>> (video output drivers?) where TED managed the same with a single +5V >>>>>> supply (and produced more colors). >>>>> >>>>> The power supply for the (analog) output stages, yeah. 8565 uses 5V as >>>>> well, I'm not sure why the 6569 needed 12V. >>>> >>>> No idea either... But I have a C64 with a 6569R3 (in ceramic :)) where >>>> the +12V supply was broken. Due to a dead capacitor the VIC only got >>>> +8V. I still got a picture, but the colors were pale and went >>>> completly away when the chip warmed up, giving a pure B/W picture. >>>> Otherwise the system was working fine. Replacing the dead capacitor >>>> restored +12V and fixed the color issue. >>> >>> Would be interesting to know whether amplifying the output would have >>> helped as well :-) >> >> LUMA was OK and didn't change after fixing the +12V supply. Just for >> fun I measured power consumption on +12V for the 6569R5 (4786 15) on >> my testboard. It draws 34-35 mA on +12V alone. > > It turns out the (internal) clock drivers and a few other things use the > 12V > supply on the 6569 (those use the normal supply on the 8565). Those can > sink > a lot of current I bet ;-) Makes me wonder why they did that. Needed +12V for the dotclock and color clock to work properly? The power comsumption on +12V helps explain why the 6569 runs so hot. Without a heatsink you'll burn your fingers on it. Still, it doesn't seem to mind. TED and the 8501 don't get as hot by a long shot but are still more prone to die. :( Gerrit Message was sent through the cbm-hackers mailing listReceived on 2011-09-04 18:00:10
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