Sega Master System II Power Base CVBS Mod.

[pc2jamma]

Hi !

The Sega Master System II Power Base with the preinstalled Sonic comes only with an RF-Modulator Output.

You can add with some cable an two RCA connectors CVBS-Video and Audio.

It is very easy. If the board is in front of you with power switch on the left side then the audio signal is the leftmost pin on the RF-Modulator. The pin in the center is the CVBS signal, but this signal is too weak for the most TVs. So im using the direct output from the video IC which can be found on the top of R21, where it is easy to solder.
Ground can be taken from the tuner box.

More details in this PDF document: http://www.rf-link.de/Sega_MS-II_PB_CVBS.pdf

It is also possible to add RGB with some effort, the signals are available at the MB3514 video IC.

Regards,

pc2jamma

[kendrick]

If you're not posing a question for conversation, I'd suggest that you add data to the Wiki. I'll admit to you that since you're a new user, posting links to external sites looks and feels like advertising more than anything else. I'd like to invite you to contribute and participate more before posting any more links, please.

[viletim]

Here's how it should be done:
http://web.archive.org/web/20050319002415/http://www.mikeg2.freeserve.co.uk/masterful/rgb.html
The various different SMS2 board revisions contain different video encoders but all are pin compattible and output RGB and composite video. The resistor and cap are only required if you don't want your video to look like shit...

But it really makes me wonder.... pc2jamma, I hope you put more thought into your upcoming widget than this hack job.

[pc2jamma]

Thank you for posting data sheet know-how.

You might have noticed that there is the RF-Modulator load in parallel. With the series resistor your picture will have lower level as needed for a good quality picture. The coupling capacitor is a CAN an no must since all TV's MUST have an input capacitor. The IC (look at the datasheet again) can easily drive a 75 Ohms load. It might be the case that you never tried the mod. on a power base.

In case of your post the resistor is needed if you want that your picture looks like shit. Otherwise you have to remove the RF-Mod.

Regards,

pc2jamma

[kendrick]

PC2Jamma, you have exactly two posts in your history and you're already offering advice in a confrontational manner. I'd like to suggest that you take a more conciliatory tone with the posters that have an established history, please.

[viletim]

Thank you for posting data sheet know-how.

You might have noticed that there is the RF-Modulator load in parallel.

Now that is total crap. If you would care to work out the resistance of this load you would know it's insignificantly high. All 6 video outputs are class AB push-pull (see data page 11), so the output won't vary according to the load (whithin its limits).

With the series resistor your picture will have lower level as needed for a good quality picture.

Maybe it's because you damaged your chip.

The coupling capacitor is a CAN an no must since all TV's MUST have an input capacitor. The IC (look at the datasheet again) can easily drive a 75 Ohms load.

The datasheet is deceptive. This chip cannot directly drive 75 ohms because it has ~1.7 volts of DC offset on it's output. The capacitor is to remove this offset, nothing more. The resistor is to set the source impedance. That's why the test circuit shows a cap and 150 ohm resistor (75 ohm in circuit, 75 in TV) as the load. That's the specified load.

The datasheet for the CXA1645 (the successor to the CXA1145 of which the MB3514 is a clone. There may be something similar in the '1145 data but it's all in japanese.) mentions:

Code Select Expand

9. Driving COUT (pin 15), YOUT (Pin 16), CVOUT
(Pin 20), and B.G.R OUT (pins 21, 22 and 23)
outputs. In Pin Description, "Capable of driving a
75 load" means that the pin can drive a capacitor
+75+75 load shown in the figure below. In other
words, the pin is capable of driving a 150 load in
AC.

.    |     75    +| |220µ
. pin|---/\/\/----| |----+
.    |            | |    |
.    |                   |
.    |            75     |
.    |      +---/\/\/----+
.    |      |
.          ---GND
         
Keep in mind that the pin is incapable of driving a
150 load in DC load in DC direct coupling.

It might be the case that you never tried the mod. on a power base.

My SMS2 has a CXA1145 video encoder, it works well with resistor and capacitor. If that will not suffice, my Megadrive2 has a MB3514 video encoder. It has a composite video output too. Guess which two components are in series with the composite video output right on the PCB...

In case of your post the resistor is needed if you want that your picture looks like shit. Otherwise you have to remove the RF-Mod.

Try removing it for yourself, it will make no difference!

[pc2jamma]

PC2Jamma, you have exactly two posts in your history and you're already offering advice in a confrontational manner. I'd like to suggest that you take a more conciliatory tone with the posters that have an established history, please.

Just one thing, due to the coupling capacitor in the TV there is no DC coupling of the output of the video driver.

May be it is better to close this topic and to remove me from the database. Please remember it was not me starting in this "confrontational manner".

Regards,

pc2jamma

[kendrick]

Let's start over. Welcome to GamesX, and thank you for contributing. As the moderator, I'm very pleased to see new users posting their thoughts and ideas. However, by putting an external link to a compiled document in your first post, you're *inviting* other people to be critical since it looks like you're only advertising for another website.

Tim has a six-year history on this forum and is responsible for originating many video mods, including the elusive Game Gear video output. He's earned the right to judge video mods 'shit' because he has demonstrated an authoritative knowledge of the subject.

PC2Jamma, you haven't earned anything around here yet. It's evident that you have drive and talent, but what you don't have around here yet is any sort of credibility. If you feel the need to defend your work, please do so with 'I' statements. 'I did this', 'I was able to make this work', 'This is the result I was able to make' and so on. You don't get so say authoritatively that a particular component or mod behaves the same way every time because we've only seen one mod you've done. 'I' statements will help you avoid derision, and a little humility won't hurt either. If everybody here sees that you're willing to admit when you're wrong, it helps your credibility more than when you get defensive and diffident. That's all.

[pc2jamma]

(..)
He's earned the right to judge video mods 'shit' because he has demonstrated an authoritative knowledge of the subject.
(..)

Noone has this right.... Not you, me or anyone else. And it is impossible to earn the right to be unpolite. The link to my document is without any advertisements or similar things, i removed the link to the pc2jamma project as soon as i read your post. By the way you might have noticed that pc2jamma is a non profit project.

Please remove my account. This is not the right place for me.

Regards,

pc2jamma

[NFG]

Sorry, we don't remove accounts 'cause you weren't happy with your reception.  You're more than welcome to simply never come back, but that's not really the kind of thing we like to encourage around here.

The GameSX forums are full of technical tinkerers from many countries, and we all love to play with hardware.  It's not easy to get along with everyone all the time, and sometimes the delivery of our posts leaves a little to be desired.  I'm probably as guilty of it as anyone, really, but we're all here because of a common passion and that's what's important to me.

I think our glorious mod kendrick might have been a little more unhappy with your first post than I'd have been, but the rest of what he says is dead on the money:  People new to a community don't get immediate and complete trust.  You earn it.  Until you do, your statements will be met with skepticism, and that's pretty much the norm in every community.