Author Topic: Question about the LM1881? (Read 2658 times)

Jetfire · « **on:** June 29, 2005, 10:20:24 am »

Hi, I would like to make a VGA to component cable for PS2. I know most of the steps to making the cable, but there are some things I don�t understand.

1.For the component cables (Red, Blue, Green) the 220uf capacitor, what is the correct voltage?

2.The PS2 pin out #6, does it connect to LM1881 pin #2? Also the 0.1uf, what is the correct voltage?

3.The LM1881 pin #8, the +5v does it connect to PS2 AV input pin #10? If pin #8 does not connect to PS2 pin #10, where does it connect to?

4.The LM1881 is pin #4 and pin #6 suppose to be connected together? After connecting these 2 wires, where does it connect to?

I'm sorry! i forgot post the Link:
http://www.gamesx.com/avpinouts/psxav.htm <- PS2 Pinout
http://www.gamesx.com/misctech/lm1881.htm <- LM1881 Pinout

Please help me out. Thanks a lot.

emuman100 · « **Reply #1 on:** June 29, 2005, 03:33:07 pm »

Component video isn't RGB with sync on green. Component video is more like S-video with the chrominance split up even further. The luma on the green and the chroma, Cr and Cb, must get converted to RGB. It's not just a cable modification. The sync is carried on the luma, the green plug, and must be stripped off the luma. The LM1881 will do this for you, but it'll only give you a composite and vertical sync. Horizontal sync will have to be aquired from the composite sync if you want both H and V sync, which most VGA monitors require.

Please post a schematic/diagram/pinout or something. We don't know what pin is what.

But, let me tell you, if you want VGA out of your PS2, you need to run a progressive scan game (no, regular ones will NOT work) as well as have a fairly complex circuit to convert the component video to VGA and do it well without much noise and with the right colors. A component video cable and a sync stripper IC won't do it for you.

Jonathan

Endymion · « **Reply #2 on:** June 29, 2005, 03:56:48 pm »

Erm. It can be done. If you look in the system preferences you will see that you can change the output from RGB to Component. If you have it set to RGB and modify a cable properly then yes, you can have VGA-level RGB from your PS2. This has been documented by a few people here, but honestly, it is probably a lot less hassle to just buy a Blaze PS2 VGA adapter. It isn't a very complex circuit, but you can get the damn thing for under $20. Why bother with all the hassle? You need a boot disc that the Blaze cable comes with to make some games work anyway.

Edit: Here's the hassle, if you really want it. If your monitor does not support sync-on-green here's a thread where folks worked on removing it, something tells me RARusk could come up with a better way but he has been working on getting the RGB from inside the console before sync is added, which is probably out of most folks' range.

Jetfire · « **Reply #3 on:** June 29, 2005, 04:08:35 pm »

Add PS2 and LM1881 Pinout.

Endymion · « **Reply #4 on:** June 29, 2005, 04:11:24 pm »

Huh? What for? everything you need to know is in the links I showed, including the LM1881M used if your monitor doesn't support sync-on-green.

Jetfire · « **Reply #5 on:** June 29, 2005, 04:20:48 pm »

I saw the link. but i still don't understand how to Connect these pinout.

1.For the component cables (Red, Blue, Green) the 220uf capacitor, what is the correct voltage?

2.The PS2 pin out #6, does it connect to LM1881 pin #2? Also the 0.1uf, what is the correct voltage?

3.The LM1881 pin #8, the +5v does it connect to PS2 AV input pin #10? If pin #8 does not connect to PS2 pin #10, where does it connect to?

emuman100 · « **Reply #6 on:** June 30, 2005, 03:41:33 pm »

Wow! Does version 2 PS2s support switching the output to RGB?

vileitm! · « **Reply #7 on:** June 30, 2005, 08:19:00 pm »

Jetfire,
Have a think about it...The maximum voltage you are working with is what? 5v? So lets be conservative and say the caps you use should be rated for at least 10v. The 0.1� caps used with the LM1881 should be of ceramic or polyester type. These typicaly have a voltage rating of 50v.

Endymion,
Regarding scraping the sync off sync-on-green video. Here's a fairly straight forward method. It's a bit crude and leaves a little blip where the sync started (due to propagation delay) but it should be good enough.

Code: [Select]

.                 ........     /composite sync
.  green o-+--C---.LM1881.----------+
.  in      |      ........          |
.          |        |               |  IC1
.          |        |/back porch    |  4053
.          |        |               |
.          |      ......          ......  ............
.          +--C-+--o   .       +---o   .  .          .
.          |    | . --o----+   |  . --o---.Buffer amp.--o green
.          |    | .o   .   |   |  .o   .  ............    out
.          R    | ......  ---  |  .|....
.          |    |  1A     GND  |   |  1B
.         ---   |              |  ---
.         GND   +--------------+  GND

The first cmos switch clamps the black level to ground (0v) and the second switches the buffer amp's input to ground whenever a sync pulse comes along.

Guest_Jetfire · « **Reply #8 on:** July 01, 2005, 02:24:28 am »

Now, In the LM1881 Pin8 the +5V. Where do the +5 connect to?

3.The LM1881 pin #8, the +5v does it connect to PS2 AV input pin #10? If pin #8 does not connect to PS2 pin #10, where does it connect to?

Endymion · « **Reply #9 on:** July 01, 2005, 02:33:33 am »

Thanks for the info tim. You post here so much why don't you register? Neat circuit but my Viewsonic 22 incher takes s.o.g. so I'm good to go.

emuman, I don't have a mini-PS2 (or is that, a PS2 2?) yet but it should have the same features. I can't think of any reason that it wouldn't work the same. The boot discs that the Blaze cables come with are needed for some (most) PS2 games that can't do progressive and it provides some way to enter "codes" to enable progressive for certain games, but the company's website has not had more codes/info on this for quite some time. The games that do progressive just work, and look great, as good as a Dreamcast for that matter, but still have that s.o.g. issue that nags a lot of people. The manual says that you don't need a s.o.g. monitor to use it but a lot of people had problems so the s.o.g. must still be there. The Blaze cable actually has an LM1881 though so it can be modified.

viletim! · « **Reply #10 on:** July 01, 2005, 09:20:28 am »

Jetfire,
The LM1881 requires 5v to power it. The PS2 outputs (not input!) +5v to feed it. If you have any doubt about which pin the voltage comes from then measure it for yourself.

Endymion,
I have registered but I can never be bothered to log in (I don't allow non-session cookies on any of my computers/browsers for privacy reasons so I can't stay perminantly logged in). Just putting my name at the name at the top works for me.

Jetfire · « **Reply #11 on:** July 01, 2005, 02:37:04 pm »

HI! viletim! Thanks for answering all question.

Yod@ · « **Reply #12 on:** July 01, 2005, 04:26:02 pm »

Quote

The games that do progressive just work, and look great, as good as a Dreamcast for that matter, but still have that s.o.g. issue that nags a lot of people. The manual says that you don't need a s.o.g. monitor to use it but a lot of people had problems so the s.o.g. must still be there. The Blaze cable actually has an LM1881 though so it can be modified.

Oh, I had this problem, it's very easy to sort out.
I just opened up the unit, cut the trace leading from the green input signal to the rest of the circuitry, cut the trace going to the green output pin (VGA pin 2), and soldered a link wire between them.

One of my friends also had one which a s.o.g. problem, but another friend says he never had to modify his adapter to remove s.o.g.

Author Topic: Question about the LM1881? (Read 2658 times)

vileitm!

Guest_Jetfire

viletim!