Re: C64 RF modulator replacement

From: silverdr_at_wfmh.org.pl
Date: Sat, 1 Sep 2012 21:20:47 +0200
Message-Id: <C6556C40-3543-41E6-B091-12CB2A003A98@wfmh.org.pl>
On 2012-07-08, at 15:19, Gerrit Heitsch wrote:

>> I laid out something like here:
>> 
>> https://dl.dropbox.com/u/58002657/C64_rf_modulator_replacement.png
>> 
>> trying to keep the signal paths (traces) short. It is not yet meant to be placed in the metal housing of the modulator but if that works well I may take some efforts to make a replacement board that goes inside the metal case. The "upper" part is an audio amp for the SIDs.
>> 
>> 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.

I built and tested the proto:

https://dl.dropbox.com/u/58002657/2012-08-31%2021.30.11.jpg

and.. in fact this is one of the sharpest C64 output I've seen. It does not exceed much (maybe still slightly better - the infamous stripes become more pronounced - the best unmodified one, but generally most of the (modulator) versions I've seen are far worse than this. The audio part works well too. In some spare time I think I shall redesign the mechanical to fit original mounting holes.

Other than that - thanks Gerrit for pointing to this solution.
-- 
SD!


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Received on 2012-09-01 20:00:18

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