Modding Cartidges, Diagrams with Stereo & Clock Oscilator ...

To know how redirect your internal Msx PSG, follow this procedure:

http://www.msx.org/forumtopic12978.html

This allow get PSG sound through stereo jack, but probably some MSX´s will need extra modifications to work ok with it. I tried that procedure with perfect results in a MSX2 HB-F9S, in Turbo-R A1-GT also works, but a tiny background noise effect appear when volume is quite high, or only high, this interference is constant, i´m trying to find solutions for this, maybe extra amplifier is needed or extra circuit to avoid that buzz interference in sound.

There is a method that allow get PSG from A1-GT engine ,but i dont want touch the engine for now in this machine, should be a way to clear the audio PSG signal without that noise, and if i´m right get the PSG from the engine makes lost sound in TV or monitor towards RGB conector, anyways this could fix installing 2 rca in scart conector, but for now i´m trying to search any way to filter the sound with normal procedure, anyone knows about this issue in A1-GT?

Hello Dantyr, about:

- Where I use the 4K7 Resistor ?

-The 4K7 resistor is located in stereo jack, is draw like a rectangle, there you can see 4701, that is the SMD resistor 4K7 or 4701 ohm.

- The 22uF Electrolitic capacitor is of what voltage ?

-You can use smd 22uF 16V.

- What is the "4701" on the stereo jack ?

-Like i said, the "4701" is a smd resistor, when you get the smd type resistor you´ll see label on it 4701 in white (that is the reason why i drawed like is showed in diagrams)

I'm thinking to do this mod on my cartridge because I have a problem hearing the SCC sound on my Sanyo 2+ (very low volume), so I think this stereo mod could be a good solution to solve this. What you think ?

What kind of cartidge do you try to modify? Maybe you could use a 25K Variable resistor for test, to try recognise the desired sound value that you want to ear, after that, you could change that variable resistor for a normal resistor with same value tested for SCC sound, PSG is another thing, because you should need redirect internal MSX PSG signal to get PSG sound through stereo jack. I dont know about Sanyo 2+ hardware to try PSG internal redirect, maybe this will be interesting to you because you can get PSG+SCC sounds with stereo jack if you try that procedure, you can see above the link.

yeah
first of all
very nice and clear pics of these modificaions!!

but i still have a question
what kind of stereo is this?
drums on one side and rest on other side?
or what?

Dhampird, thank you again for the new ideas.

I already bought some parts today in a local store and I will do part of your first schematic to just redirect SCC through an RCA female jack and the PSG would come through directly from the MSX audio out. As I use an X230 Logitech 2.1 speakers, the SCC will come in from one channel and the PSG in another channel. Would be two rca cables plugged (one on the cart and other on the MSX), but it's a small price to pay to not touch inside my MSX. As far as I know, no one never found schematics for the Sanyo 70FD.
I will also test the OPFX /P option to use the internal PSG on the Megaflash to see what will be the better combination.

After all the modifications I will take some photos to put on this topic if you don't mind.

Thanks,
Daniel

Hi!

Just asking, what is the point of the oscillator in a cartridge? Is there some problem with SCC if an MSX in installed with turbo, and this removes that problem?