S/PDIF Sega MD 1: possible solution Thread moved seelastpost

[brendanraymond]

Hi

As you guys may know, I have been working on another S/PDIF mod for the Sega Saturn... a fairly strait forward mod.

However, I am now looking into doing a similar mod for my MegaDrive.

I have not seen any mod like this so far on the net, even after searching.

I did however stumble apon this: http://nfggames.com/forum2/index.php?topic=3719.0

Can anyone shine any light onto this issue?

[CRTGAMER]

I need to do something like that on my Vectrex's, or maybe just a lotta shielding. If you ever heard a Vectrex, it is buzz overkill, makes your Sega sound like THX DOLBY Surround by comparison.

[brendanraymond]

Are you sure its just the system? It could be just a ground loop in you home theater set-up.

Or the vetrex is just shit lol

[CRTGAMER]

Are you sure its just the system? It could be just a ground loop in you home theater set-up.

Or the vetrex is just shit lol

Its the Vectrex, both of them. Design flaw of shielding causing the buzz. But very unique being the only home unit that offers Vector Graphics as in Asteroids or Space Wars. There is a fix involving removing a couple resistors and some soldering.

http://classicgaming.gamespy.com/View.p ... 21&game=12
http://www.playvectrex.com/

[brendanraymond]

has anyone used this chip: "Yamaha YM2608" as aposed to the "Yamaha YM2612" to be coupled with another sound processing chip to output spdif?

since it doesn't have an internal DAC, it might be possible... however, I am not sure...

I plan to use the sega megadrive version 1. I will isolate the sound processing chip: YM2612

http://en.wikipedia.org/wiki/Yamaha_YM2612

And then using a multipole double throw switch to connect up YM2608 through the 6 normal FM channels and leave the remaining 10 channels open (not connected to anything)

http://nemesis.hacking-cult.org/MegaDri ... slated.PDF

And then using the digital OPO sound output from YM2608 to input into CS8406

http://pdf1.alldatasheet.com/datasheet- ... S8406.html

And then using the spdif output to send the signal to a toslink transmitter.

If the output from YM2608 fits the serial input into CS8406, then i cant see any reason why it cant work??? I am not sure about the output of the serial audio bit clock and word clock.

I am also looking into the possibility of CS8416 and other chips from cirrus logic though im doubting that they will be compatable :S

Please tell me what you think.

[brendanraymond]

http://gendev.spritesmind.net/forum/viewtopic.php?t=730

[brendanraymond]

Could someone please mark this up?

I havn't much clue what I am doing... but I was following summing junction logic: http://www.eecs.tufts.edu/~dsculley/tut ... amps7.html

The stuff in red is what I am unsure about.

[brendanraymond]

http://www.sega-16.com/forum/showthread.php?t=11361

It seems there is a mod for the MD1 similar to my previous concept, however, there is now an amplifier involved.

if anyone has any info at all!... please let me know ^^

cheers!

[brendanraymond]

So how did you obtain 3v for your virtual ground? just a 6v reg with a resistor? how many buffers and virtual grounds could I power with 1x 6v reg?

Also, how would wone work out the final voltage output with all these op amps and resistors in the way? I added a resistor and a virtual ground to the "cirrus" circuit to allow for amplifying the signal up to 6volts max... would that work do you think?

So, here is the latest markup. please let me know if i should change anything.

Also is VQ voltage quadrupler?

[brendanraymond]

after my exams, i'll finish this baby off too.