Re: Is it at all possible?

On 2017-02-19 14:12, silverdr@wfmh.org.pl wrote:
>
>> On 2017-02-18, at 21:59, HÁRSFALVI Levente <publicmailbox@harsfalvi.net> wrote:
>>
>>> Not quite... You can get a clear picture from a 6569R1, 6569R3 or 6569R4
>>> (that one is rather rare) as well. The problem on the older boards is
>>> mostly the modulator. Replace it with a simple video amp and you will
>>> have a very good picture. Ok, you lose the RF output, but who is using
>>> that anymore?
>>
>> There is clearly a visible difference between an R3 and an R5 on a 250466 board. (I've been using an R3 after having killed the original R5 of the machine / before I could obtain another one.)
>
> Could you elaborate/describe the difference? It's been some time since I tried those (and it was not in the '466 either) but I didn't notice anything striking. The R1 with its luma levels makes a noticeable difference but the later ones?
>

Less contrast, more blurry / noisy / subjectively darker startup screen. 
Nothing as obvious as the 6569R1 with its fewer luminance levels, but 
still something clearly noticeable.

(Worst of all, with the R3 installed the machine started to exhibit VSP 
crash symptoms, which it never did previously. That machine was and 
still is one of two C64s (a 65xx and a 85xx based one, both late models) 
that I regularly used to play scene demo prods; so I felt the result 
somewhat less than acceptable. I was lucky to obtain a new (judging from 
the chip itself, probably a new old stock) 6569R5 again sometime later. 
I don't know if the R5 effectively has the the VSP dram corruption 
problem fixed, or the fact that the machine did crash with the R3 but 
did not with the R5 was merely a result of different combinations of 
factors. I'd suspect the latter case.)

Levente


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