PC engine RGB mod

[teknogrebo]

Hi,

I recently bought a white PC engine and need to do some sort of video mod on it so that I can actually play it on my PAL tv.  I've looked at both of the mod pages on the gamesx site (i.e. the old and new), and I am a bit confused about a couple of things which I was hoping you nice people here might be able to answer.  Firstly, there is mention of LM1881 circuit.  Is this circuit actually a necessity?  I can solder connections (I've done a few chip mods in my time), but I'm rubbish with circuit diagrams etc, so I'm kind of hoping that it isn't required.  Similarly, is the 100 ohm resister a 'suck it and see' type affair?

TIA for any info.

Tom

[NFG]

Most SCART TVs can use composite video as sync, so the LM1881 is not necessary regardless of the signal used for sync.

If you're referring to the 100ohm resistor on the SCART blanking line, no it's not required for many TVs (but it IS required for some).  Try it and see.  =)

[Rockard]

oooh, I am just about to modify my own small white pc-engine myself =).

I'm planning to replace the RF with a mini 9-din for RGB! Perfect for the small rf-hole (no cutting plastic or drilling necessary this way), and it will be consistent with the controller which also uses a mini-din.

I have just removed the antenna box inside the pcengine, and now the clock is four in the morning, sooo.. I'll be back! =P

/Rickard

[Guest]

Most SCART TVs can use composite video as sync, so the LM1881 is not necessary regardless of the signal used for sync.

If you're referring to the 100ohm resistor on the SCART blanking line, no it's not required for many TVs (but it IS required for some).  Try it and see.  =)

Okay.  That's good news. Thanks for the info

[viletim]

Similarly, is the 100 ohm resister a 'suck it and see' type affair?

If you leave it out it won't switch the TV into RGB mode automaticaly. On a lot of SCART TVs that's the only way to put the TV into RGB mode. It's worth the 2 cents to add the resistor, if only for the convenience of not having to play with the TV every time you turn on the PC Engine.

Most SCART TVs can use composite video as sync

Lawrence, that should be: All SCART TVs require composite video as sync. (ok, perhaps there are some exceptions, but I've never seen any)

[Guest]

Similarly, is the 100 ohm resister a 'suck it and see' type affair?

If you leave it out it won't switch the TV into RGB mode automaticaly. On a lot of SCART TVs that's the only way to put the TV into RGB mode. It's worth the 2 cents to add the resistor, if only for the convenience of not having to play with the TV every time you turn on the PC Engine.

Most SCART TVs can use composite video as sync

Lawrence, that should be: All SCART TVs require composite video as sync. (ok, perhaps there are some exceptions, but I've never seen any)

It's not the cost of the resister, it's the time taken to get it.  I don't have easy access to an electronics shop where I live, and I'm impatient to do the mod, as I haven't played on the little thing at all  I guess I'll wait though and make a trip into town to get the resister.

You've managed to confuse me more about the composite thing though, are you saying that the LM1881 mod is actually not only unneccesary, but undesirable for most scart TV's?

[viletim]

Guest,
It doesn't have to be a 100 ohm resistor anything from about 80 to 200 ohms should do the trick. Maybe you could raid the part from a broken (or even working as long as it doesn't belong to you :) electronic thing you might have lying around.

You've managed to confuse me more about the composite thing though, are you saying that the LM1881 mod is actually not only unneccesary, but undesirable for most scart TV's?

Yup, that's right. A SCART TV has an 'LM1881 equivalent' (sync stripper) circuit inside it already.

[teknogrebo]

It doesn't have to be a 100 ohm resistor anything from about 80 to 200 ohms should do the trick. Maybe you could raid the part from a broken (or even working as long as it doesn't belong to you electronic thing you might have lying around.

Thanks for the extra info.  However, I wouldn't know one resistor from another (I know they have coloured bands on - but I can't remember which one is what, I am also colourblind which doesn't help either)  As I said before, I can solder joints pretty well, but that's about it.  I'll wait a bit and go and get a resister.  That way I know what I have in my hands is the correct thing