On 2012-05-13, at 20:41, Gerrit Heitsch wrote: > The blurriness, if present, can usually be remedied by removing the RF modulator and replacing it with a little circuit that does the signal conversion to proper luminance/chrominance signals. Most possibly yes. I haven't tried that. Neither analysed the differences between various modulators. Don't know even if schematics for all of them are available. AFAIR there was noticeably more variants than those listed in the service manual. > It's only 2 transistors, a 1N4148, some resistors and 2 capacitors. Accidentally having diagram at hand? > It's not a matter of the clock generator, the 8701 is not a PLL, its output does contain some jitter. Because the change happened between those revision, I (uneducated guess) thought it was [also] the characteristics / stability of the clocks. Of course it might be also that between the revisions not only the "discrete" circuit was replaced but also the modulator. In practice the effect was a noticeable difference in luma sharpness. > A while ago I did an experiment, using 3 1N4001 diodes I limited Vdd of the 6569R5 on my test board to about +10V instead of +12V. The chip still worked fine, including the color output, just got a bit less hot. Interesting idea - I haven't tried that. You put a divider there or something more sophisticated? >> Yup - those were IMHO the best boards. With lots of unused space though. Mine (the one I refer to) is 250425. I keep it because it is a) the original first I bought and b) it is customised, with practically everything socketed, etc. > > Now you only need to replace 2114 color RAM with a CMOS version I have never thought of/measured it - is the difference worth the effort? > and the 7805 and 7812 with state of the art switching regulators and you're set. Yup, with the VIC working at lower temp and other power savings it might pay, I guess. Have you done this with yours? If yes, then what parts you used? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-05-13 20:00:10
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