Help! Sega Master System 2 RGB mod - no Sony chip?

I was really hoping to get this done this evening... I am attempting to modify my PAL Sega Master System 2 for RGB output and 60hz. Am following this guide:

http://www.mmmonkey.co.uk/console/sega/sms2-av.htm

However, when I reached the step about the Sony chip, I noticed my model doesn't have a Sony chip, but a generic-looking chip labelled "MB3514 9239 M24". The surrounding circuitry is different, too. The board is dated Nov 1992.

It's not a clone or anything - there is SEGA branding on the board and I received it boxed. Does anyone know if the RGB mod is possible on this board?

Thanks

 

Don't remember where I got it from but this has never failed me
By the way if you try to take composite video from a machine with one of these chips in it will have horrible ghosting.

 

Perfect! I really appreciate that, thanks for the response. The evening's not a write-off yet.

 

This console has many mod options. RGB and 60hz are the relatively easier recommended ones.

Should be possible to go overboard with things like an FM sound chip, Japanese switch that affects dual language games, RGB to component circuit (best used on 60hz CRTs who lack RGB)...

 

Did you pull composite directly from the chip without any additional components?

 

These pins are a bit of a bitch for a heavy-handed chump like myself. The traces underneath look similar to mmonkey's diagrams (pretty sure I can see the RGB traces at least) but they're not the same and I don't have a multimeter to hand, so I'm going straight for the pins. The Jack Daniels isn't exactly helping matters either...

 

I used electrical tape to cover up the pins as I was soldering when I did mine. The procedure is the same as the CXA1145 with a 220 uF cap and 75 ohm resistor on each line.

 

I don't remember to be honest, it's been a while since I last did it, I think I experimented with several different places
As I recall I settled on the point which goes into the RF box with a resistor and a capacitor or without any components, I forget. This point was perfect for a system with the other video chip and I'm assuming it's the best one I found or I wouldn't have settled for it.
Aside from that couldn't tell you.
Though if you have any suggestions I'm willing to crack it open again for another go.

 

Got the R,G,B and Sync joined nicely as per the posted diagram. Mmmonkey's guide shows white wire for RGB switching voltage - anyone know if or how this factors in on this chip? I'm not 100% clear on the various types of RGB and what is used here. Thanks

edit: found this, not that it helps me much http://members.optusnet.com.au/eviltim/gamescart/MB3514.pdf

edit 2: never mind, according to this page http://console5.com/wiki/CXA1145 pin 12 on the sony chip that mmmonkey mentions = vcc1, which on the mb3514 is the same pin, so i'm going with that. it's just confusing because he's using the traces instead of the pins.

 

If this is the start of a long love of modding, I'd recommend you also grab a digital multimeter and take advantage of their ability to trace lines on the PCB. Makes it very handed when you struggle with soldering to small pins on ICs - I'm not the best at super-fine work myself, but the multimeter makes it much easier to find alternative points to solder nearby and is invaluable when testing your connections.

 

Without knowing more specifics I'd be hard pressed to give any suggestions short of pulling the signal from the chip directly and reproducing whatever 'application circuit' the chip's datasheet gives. Can't seem to find the datasheet but it looks like the same encoder was used in some Mega Drive 2s.

More curious than anything as we Americans only got one SMS revision and its stock composite is rather nice. S-Video with a single transistor as an amp is even better.

 

I used composite as sync with mine, I just tapped composite directly from the MB3514 and added a 220 uF cap and 75 ohm resistor like with the RGB lines.

 

Yep same as Mega Drive 2, here is the datasheet.

http://members.optusnet.com.au/eviltim/gamescart/MB3514.pdf

MB3514 doesn't require amp for s-video just the simple resistor and capacitor.

A nice, neat way to do composhit on SMS2 is to remove the RF box, check or replace R21 with a 75ohm resistor (some have a 22ohm resistor in it's place), remove R29 and FB, swap C38 for 220uF from the common point of R29 and FB5 tap video from here. Audio can be taken from pin 3 of the old RF box or along with a 10uF cap from pin 9 on the video encoder.

I have recently re-done my RGB'ed SMS2, once I find the pics of it I will add them up.

 

A multimeter that has a buzzer for continuity in it is best! Wouldn't leave home without mine.

 

Yup, that magic beep is a glorious sound

 

A beep?!?! Must be a high class multimeter you have there! :wink-new:
Mine does more of a dying chirp. It sounds like a stepped on cricket!

Edit: Oh the SMS2 uses the same chip as the MD2. I knew I'd seen that chip somewhere before!

 

Yea the last of them did.

Here is my SMS2

Old RGB I had the socket flush so the RGB socket juuuuussssstttt made it.



The old inside was pretty messy as I added to it, added to it.



The underside of the new board. I initially just had the single controller port mod, hence the different type of wire. I also had a blow out with my composite to the RGB (derp), I re-located this to where circled.



All back in, I really should have shortened the FM board enable switch but meh.



The back of the console, complete with crooked FM switch sticker (later fixed lol)!



Please excuse the quality of the pics. These are taken at 5am in the morning as the only time I get to do this stuff is getting up early and doing it before work.

 

Damn! That thing is full, reckon you could fit any more circuits in there? :wink-new:
Very impressive job though!
Lucky for the Master System it had all that height, or there'd be trouble...!

 

lol Thank you, yes it is pretty full, I guess a BIOS change (maybe), reset switch (not really needed) and adding in a card slot (uggh why?) would be interesting but I am happy with how it is now.

Here is a similarly modified SMS, I bought this as faulty from somewhere (???? long time ago). It rattled and wouldn't work so I popped it open and the BIOS chip had been hacked out and was loose in the console! I only had "nubs" to solder to hence the wires. I could have maybe bought another faulty console for the BIOS....I may do this as my only card game is Hang on and guess what is "built" in. So if I put in Hang on which one am I playing? lol! Anyway this one has a REV 2 FM board in it so no need for the language switch as this has now been built into it (via a 3 way switch so OFF, ON, ON JPN). I have removed the RF module for is I ever want to put S-video in it.



SMS model 1s are so much easier to modify....

 

Oh man! You got Hang on built in? :topsy_turvy:
That kicks the crap out of Alex Kidd in Miracle World!

A rattling noise is never a good sign from inside anything electrical. Unless it's a Toshiba 2.5" hard drive.
RATTLE NOISE IS NORMAL! So they tell us. :suspicion: