PC Engine RGB mod for GBS8220 scaler

[mrkotfw]

I went ahead and tried the following RGB amp for each R, G, and B (not sync). I get a black picture with sync. Now, I would imagine that if sync is too weak, wouldn't I get a distorted image but with colors?



Is there a particular mod that I'm not aware of that'll work with the GBS8220 scaler? I also am using the Sync Strike.


Any help is greatly appreciated!

[mrkotfw]

Bump... there has to be someone with this set up...

[Retro Access]

Are you using a white PC Engine, pulling composite through a sync seperator or just pulling sync?

Pull sync and the sync needs a buffer, I have one that works.

Did you build the sync amp recommended on GamesX yet? Or not bothered amping sync? Try their amp first if not.

I definitely have this working though, used a video amp IC on a white PC Engine, also used it on sync as well as composite (white PC Engine composite is weak.)

Any other PC Engine other than white should work with its regular composite from the AV port run through a sync seperator. If you are using sync though it needs a buffer as none of these consoles have buffered sync.

[Fudoh]

Sorry for the thread-hijack, but let me add a question:

I have a RGB-modded interface unit which works great with the XRGB-Mini - if used with a Core Grafx or Core Grafx 2. The white Engine works fine as long as it's used with HuCard games, but it loses sync when used with (several) CD games. This ranges from dropouts in Ys 1/2 to complete loss of picture with Winds of Thunder.

Which sync amp on GamesX are you refering to ? The sync line is buffered on the transistor-based mod I have in the interface, but not boosted. I'd love to get this running while keeping the mod compatible to the Core1/2 units.

[mrkotfw]

Are you using a white PC Engine, pulling composite through a sync seperator or just pulling sync?

Pull sync and the sync needs a buffer, I have one that works.

Did you build the sync amp recommended on GamesX yet? Or not bothered amping sync? Try their amp first if not.

I definitely have this working though, used a video amp IC on a white PC Engine, also used it on sync as well as composite (white PC Engine composite is weak.)

Any other PC Engine other than white should work with its regular composite from the AV port run through a sync seperator. If you are using sync though it needs a buffer as none of these consoles have buffered sync.

Sorry for not providing that info.


I'm using a PC Engine Duo RX. I'm getting composite sync through a sync stripper. So straight from the 8-pin MINI.

[RGB32E]

I really don't get why eBay sellers such as dojindance don't replace the +5VDC pin on the DUO systems with buffered CSYNC... that's what I did with my TurboDuo! Sync stripping CVIDEO to get CSYNC seems absurd, especially when CSYNC from the Hu IC is available. It's like stopping at 75% of the mod???

[Retro Access]

Are you using a white PC Engine, pulling composite through a sync seperator or just pulling sync?

Pull sync and the sync needs a buffer, I have one that works.

Did you build the sync amp recommended on GamesX yet? Or not bothered amping sync? Try their amp first if not.

I definitely have this working though, used a video amp IC on a white PC Engine, also used it on sync as well as composite (white PC Engine composite is weak.)

Any other PC Engine other than white should work with its regular composite from the AV port run through a sync seperator. If you are using sync though it needs a buffer as none of these consoles have buffered sync.

Sorry for not providing that info.


I'm using a PC Engine Duo RX. I'm getting composite sync through a sync stripper. So straight from the 8-pin MINI.

I haven't tried the Duo yet but I kinda assumed the others would work fine because they have composite video as standard and certainly, the Core Grafx worked.

Fudoh, I haven't got a briefcase CD type unit to try this and see if I can get the same results/fix it, but I do have a Duo here, I mean did OP do the full amp ie. there's a circuit for sync too, but obviously no as he is using composite video. Now on the white PC engine composite video>sync stripper absolutely did not work, but I have not tried the gamesx mod out on the GBS8220, although I have tried a modified version on the Mini. What I was using was a THS7314 based amp with composite pulled from the usual spot on the EXT port. When that didn't work I ran composite video through another THS7314 IC and that worked perfectly on the GBS8220. As does running sync through this amp. OP, did you try using sync direct to the device or anything like that, I am just asking out of curiosity because I have not had much time to test various mods on various scalers for PCE. If it helps then pulling csync from the HuC6260 then running it through a THS7314 based amp may well work. Now I will see if there is a simpler way to do it than using an SMD IC (I had lots lying around for N64 mods), but yeah, you can cut out composite video and use sync instead.

OP has me intrigued anyway, I have a Duo being sent in the mail to me for a mod so at the very least I will have time to try to get sync working from this console on the GBS8220. Unfortunately my GBS8220 board is a bit fried to say the least and has graphical issues all over the place, hence not bothering testing out more mods on it. At the very least though I can say whether a console works or not on it, it still works for testing purposes and still keeps sync when fed the right signal.

[RGB32E]

When that didn't work I ran composite video through another THS7314 IC and that worked perfectly on the GBS8220.

Duh!!!?

[Retro Access]

I really don't get why eBay sellers such as dojindance don't replace the +5VDC pin on the DUO systems with buffered CSYNC... that's what I did with my TurboDuo! Sync stripping CVIDEO to get CSYNC seems absurd, especially when CSYNC from the Hu IC is available. It's like stopping at 75% of the mod???

Because eBay sellers like to sell with the greatest range of compatibility possible, ie. you don't want the inevitable "Your mod does not work on my SCART TV" because you cut out +5V. The huge majority of people who buy RGB mods for PCE do not have expensive scalers, they have SCART TVs because they are in Europe. They just want it working on their TV and leaving composite in gives them another option in case their TV is finicky with the signal for some reason.

[Retro Access]

When that didn't work I ran composite video through another THS7314 IC and that worked perfectly on the GBS8220.

Duh!!!?

?

If you are referring to getting composite video working as the sync signal, as I say I am leaving as many options open to people as possible so I leave it in the output socket. Actually I wire up white engines with a 9 pin Genesis 2 type socket with that exact pinout.

The video and RGB amp was in the console, the cable sold with it was a Genesis 2 type SCART with the same 75 ohm resistors, 220uf caps and beyond that it is up to the customer what scaler/TV they use. Leaving in composite as a working signal means that if they want/need to they can replace the SCART with a standard Genesis 2 one later.

[mrkotfw]

Are you using a white PC Engine, pulling composite through a sync seperator or just pulling sync?

Pull sync and the sync needs a buffer, I have one that works.

Did you build the sync amp recommended on GamesX yet? Or not bothered amping sync? Try their amp first if not.

I definitely have this working though, used a video amp IC on a white PC Engine, also used it on sync as well as composite (white PC Engine composite is weak.)

Any other PC Engine other than white should work with its regular composite from the AV port run through a sync seperator. If you are using sync though it needs a buffer as none of these consoles have buffered sync.

Sorry for not providing that info.


I'm using a PC Engine Duo RX. I'm getting composite sync through a sync stripper. So straight from the 8-pin MINI.

I haven't tried the Duo yet but I kinda assumed the others would work fine because they have composite video as standard and certainly, the Core Grafx worked.

Fudoh, I haven't got a briefcase CD type unit to try this and see if I can get the same results/fix it, but I do have a Duo here, I mean did OP do the full amp ie. there's a circuit for sync too, but obviously no as he is using composite video. Now on the white PC engine composite video>sync stripper absolutely did not work, but I have not tried the gamesx mod out on the GBS8220, although I have tried a modified version on the Mini. What I was using was a THS7314 based amp with composite pulled from the usual spot on the EXT port. When that didn't work I ran composite video through another THS7314 IC and that worked perfectly on the GBS8220. As does running sync through this amp. OP, did you try using sync direct to the device or anything like that, I am just asking out of curiosity because I have not had much time to test various mods on various scalers for PCE. If it helps then pulling csync from the HuC6260 then running it through a THS7314 based amp may well work. Now I will see if there is a simpler way to do it than using an SMD IC (I had lots lying around for N64 mods), but yeah, you can cut out composite video and use sync instead.

OP has me intrigued anyway, I have a Duo being sent in the mail to me for a mod so at the very least I will have time to try to get sync working from this console on the GBS8220. Unfortunately my GBS8220 board is a bit fried to say the least and has graphical issues all over the place, hence not bothering testing out more mods on it. At the very least though I can say whether a console works or not on it, it still works for testing purposes and still keeps sync when fed the right signal.

I was using the THS7314 originally on each color R, G, and B. That gave me the same results (sync, but a black screen). I then tried the RGB amp (the one I posted in the OP) and that gave me the same results.


I can certainly try to get sync straight from the chip, but chances are it's going to be the same thing. Either way I can try.



So you coupled two THS7314's to get sync to work? That sounds mighty scary... Maybe a feedback loop would of worked where you connect the output to another input of the same chip?



If you could test and please keep me updated, that would be great!

[Retro Access]

Are you using a white PC Engine, pulling composite through a sync seperator or just pulling sync?

Pull sync and the sync needs a buffer, I have one that works.

Did you build the sync amp recommended on GamesX yet? Or not bothered amping sync? Try their amp first if not.

I definitely have this working though, used a video amp IC on a white PC Engine, also used it on sync as well as composite (white PC Engine composite is weak.)

Any other PC Engine other than white should work with its regular composite from the AV port run through a sync seperator. If you are using sync though it needs a buffer as none of these consoles have buffered sync.

Sorry for not providing that info.


I'm using a PC Engine Duo RX. I'm getting composite sync through a sync stripper. So straight from the 8-pin MINI.[/quote]

I haven't tried the Duo yet but I kinda assumed the others would work fine because they have composite video as standard and certainly, the Core Grafx worked.

Fudoh, I haven't got a briefcase CD type unit to try this and see if I can get the same results/fix it, but I do have a Duo here, I mean did OP do the full amp ie. there's a circuit for sync too, but obviously no as he is using composite video. Now on the white PC engine composite video>sync stripper absolutely did not work, but I have not tried the gamesx mod out on the GBS8220, although I have tried a modified version on the Mini. What I was using was a THS7314 based amp with composite pulled from the usual spot on the EXT port. When that didn't work I ran composite video through another THS7314 IC and that worked perfectly on the GBS8220. As does running sync through this amp. OP, did you try using sync direct to the device or anything like that, I am just asking out of curiosity because I have not had much time to test various mods on various scalers for PCE. If it helps then pulling csync from the HuC6260 then running it through a THS7314 based amp may well work. Now I will see if there is a simpler way to do it than using an SMD IC (I had lots lying around for N64 mods), but yeah, you can cut out composite video and use sync instead.

OP has me intrigued anyway, I have a Duo being sent in the mail to me for a mod so at the very least I will have time to try to get sync working from this console on the GBS8220. Unfortunately my GBS8220 board is a bit fried to say the least and has graphical issues all over the place, hence not bothering testing out more mods on it. At the very least though I can say whether a console works or not on it, it still works for testing purposes and still keeps sync when fed the right signal.[/quote]

I was using the THS7314 originally on each color R, G, and B. That gave me the same results (sync, but a black screen). I then tried the RGB amp (the one I posted in the OP) and that gave me the same results.


I can certainly try to get sync straight from the chip, but chances are it's going to be the same thing. Either way I can try.



So you coupled two THS7314's to get sync to work? That sounds mighty scary... Maybe a feedback loop would of worked where you connect the output to another input of the same chip?



If you could test and please keep me updated, that would be great![/quote]

I just used one of those amps for the rgb, and another amp for the sync.

This was on the white PC Engine. I will try it with the Duo I have arriving in the mail, I really have very little time to experiment so I'll just put the extra circuit in the console and try that out on GBS8220. I have my own Duo here but it needs repairs and I have so, so little time to get around to stuff. Glad you can already deal with the THS7314 amp and you know how to do it.

I would love to fix all those broken quotes but my Macbook Air has a broken touchpad so I can't, short of highlighting every paragraph.

[Fudoh]

I have an external booster here with me that uses two transistors in row per color channel. Great results, so coupling two THS7314 shouldn't be a problem per se.

Sync vs. stripped composite, either from the expansion port or directly from the chip shouldn't matter in the actual results - it's all the same.

The 5V output from a white PCE can't be used to power a LM1881, at least not on the Mini - it's a mess.