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Akira
Registered: Oct 2003
Posts: 52 |
8580 digifix woes
I just tried to apply the 8580 digifix but I am running nto trouble.
Basically it works, boosting the digis, but everything else goes quiet.
I must be doing something wrong. I basically just connected a resistor to the EXT-IN pin (which I lifted) onto the GND pin of the SID. I noticed that if I remove the resistor then I can't hear anything. Maybe it is the wrong resistor, but why grounding the pin yields no audio?
Am I supposed to lift the GND pin too?
I wanted to put this on a switch so I can have noise reduction or digifix selectable, as I know the digifix will break a bunch of 8580 tunes.
My SID is a 8580 R5 and the motherboard is a REV.B ASSY 250469
There's no problem with the machine since after I got scared I blew a SID, I reverted the whole process (I had applied the mods through an intermediary socket, as suggested by Lemming) and it's running fine. I noticed Lemming mentions PIN22 on his article on VN#58 but every schematic online denotes pin 26 as EXT-IN and I used that (pin 22 is D7 or something) |
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Akira
Registered: Oct 2003
Posts: 52 |
Well as I said, I DID try "just any" resistor,m and all I managed to do was to hear all digi and no synth.
I did add it to a switch though, but it didn't really work out. I am having ridiculous roblems with this modification.
Should I also lift the PIN 14 (ground) if the SID or only PIN 26? Sorry about so many questions, but you all can agree views on this matter are all very varied :) |
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
the problem with the one resistor solution is that the result will wildly depend on the individual SID. personally i would connect a potentiometer in the 1MegaOhm range between VDC and GND and then the slider to ext-in, which then will be very stable and also adjustable :) |
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lemming
Registered: Oct 2009
Posts: 44 |
Try the pot like Groepaz suggested (no pun intended:D) but most importantly never ever lift the GND pin of SID or any chip :-)
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chatGPZ
Registered: Dec 2001
Posts: 11100 |
LOL |
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nice
Registered: Mar 2010
Posts: 4 |
Hi, people,
I've accidentally bought a rather unusual C64. It's a C64C model made in Hong-Kong, containing an 8580R5 SID chip. As far as I can hear it, its sound is identical to an usual 8580 both for quality and volume. However, it's digital voices are even a bit louder than that of a 6581 based machine. (I compared it to another C64C and an old C64 using International Karate.) Checking its board it doesn't seem to contain any digifix/digi boost enhancement. Have you ever met a similar machine? What can be the reason of this behavior? |
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booker
Account closed
Registered: Jul 2003
Posts: 333 |
try different sid in the same mobo and hk sid on different mobo |
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Zer0-X
Registered: Aug 2008
Posts: 78 |
Directly digi-capable 8580 aren't exactly rare, but not very common either. They do exist. |
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booker
Account closed
Registered: Jul 2003
Posts: 333 |
there, thx |
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nice
Registered: Mar 2010
Posts: 4 |
OK, I swapped SID chips between this machine and a German made one with the same MB revision. According to my experiences the digi superpower (or at least the best part of it) is beared by the motherboard, not the IC. |
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booker
Account closed
Registered: Jul 2003
Posts: 333 |
Cool |
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