Is all this really neccesary??

[GZeus]

http://baku.homeunix.net/RGB/PCE_DuoRX/PCE_DuoRX.html

There seems to be almost too much thought going into this mod.

[NFG]

That's pretty impressive, I'll have to give it a shot.

The RGB amp on my site results in some noticable vertical lines, perhaps this mod avoids such complications?

[blackevilweredragon]

Is this symbol supposed to be capacitors?  I've never seen them like that!
-|/|-
-|/|-
-|/|-

Usually I juse see these: -| |- or these (for polarized capacitors): -| (-

[viletim!]

I can't read the text and I don't have any software to read the .sch file. But from the pictures alone it seems a bit over the top. The author used video video amp ICs (which is a very good idea if you can actually buy the damn things)  so why bother with transistors and stuff on the input?

bewd,
If you're talking about pce_rgb.jpg then that's the japanese symbol for electrolytic capacitor. The EU one looks like -[] |-. I think -| (- in just a normal capacitor, no indication of polarisation, an american thing perhaps?

[blackevilweredragon]

I can't read the text and I don't have any software to read the .sch file. But from the pictures alone it seems a bit over the top. The author used video video amp ICs (which is a very good idea if you can actually buy the damn things)  so why bother with transistors and stuff on the input?

bewd,
If you're talking about pce_rgb.jpg then that's the japanese symbol for electrolytic capacitor. The EU one looks like -[] |-. I think -| (- in just a normal capacitor, no indication of polarisation, an american thing perhaps?

yea, if that's the case, it's an american thing..  cause these are symbols i follow:

-| |-  Non Polarized Capacitor
-| (-  Polarized Capacitor
-/\/\/- Resistor

[Endymion]

Jesus. I look forward to Lawrence's translation?

[baku]

I'm the author of that Website.
Excuse me. I'm poor at Engilish. Please read the page using machine translation.
http://babelfish.altavista.com/babelfish/t...FPCE_DuoRX.html

I think that all they are required.
The circuit is for outputting the signal of HuC6260 so that it may become 0.7 Vp-p in 75-ohm terminus.

NJM2267 is common video amplifier IC in Japan that it is easy to buy. It is IC which is easy to use NJM2267. However, a gain is unchangeable.

The RGB signal of HuC6260 is 4.2V to 5V, i.e., 0.8 Vp-p.
A signal is divided by resistance so that it may finally become 0.7 Vp-p. However, HuC6260 cannot drive the load.

Then, it once buffers using Emitter Follower.

[NFG]

Hi, bakuchikujuu.  

Welcome to my forum.  =)

Thanks very much for clarifying your mod.  Many of us are big PC Engine fans, and will be happy to have a better RGB amp to play with.

[GZeus]

Irashyaimase bakuchikujuu-san!
Sumimasen, kono persokon romanjishika dekinain dakara... -_-
Tonikaku, setsumeshite doumo harigatogozaimashita!

Moshi betsu no geemu no koto wo hanashitai nara, boku ni oshiete kudasai. Hiragana to SUKOSHI kanji yomeru dakara.
Manga to anime de Nihongo narata no de kanji to keigo sugoku heta...

And to anyone who can't read this, I offered to help him inform us on anything else.

[baku]

Hi, Lawrence.

It will be hard to buy NJM2267 except Japan, it could construct a circuit which was alike using IC of the similar function. But, It thinks that it is awkward hack.

A convenient IC LT6552 was found. If this is used, the circuit of this function will be able to be made more simply.

LT6552 - 3.3V Single Supply Video Difference Amplifier
http://www.linear.com/pc/productDetail.do?...009,C1044,P2359


GZeus-san, Ohenji arigatou!
GZeus-san no Nihongo ha nakanaka jouzu dato omoimasu-yo.
Keigo ha nihonjin demo kekkou muzukashii mono desu.

[viletim!]

If anyone wants to try a PCE video amp based on a real video op-amp (like the LT6552 that bakuchikujuu suuggested or the MAX4451 which is available from Futurlec) then I'd recommend a differential amp configuration. These opamps don't like their input to get any higher than Vcc-2v so you'd have to divide the input by two and double the gain to four (from the usual two). The negative input is to null the huge DC offset (4.2v!!) of the input signal.

Code Select Expand

.+5v
. |
. R
. R<---RRR-+--RRR--+
. R        |       |
. |        | |\    |
.---GND    +-|-\   |   75
.            |  >--+--RRR--o video out
.Vid --RRR-+-|+/
.in        | |/
.          R
.          R
.          R
.          |
.         ---GND  

[vkp_ashley]

I finally got around to doing bakuchikujuu's amp, and I'm happy i did. It seems to fix not only the dim picture of unamped RGB but also that vertical line problem with solid colors. Take a look at the before and after photos. The difference with and without the amp is really significant. I recommend this RGB mod to anyone who still owns a Duo.

Before [Monitor: Atari SC1224]

After [Monitor: Atari SC1224]


Before [Monitor: Sony PVM-1910]

After [Monitor: Sony PVM-1910]


Here's my setup, which is pretty much the same thing (I think) as bakuchikujuu, except I use a domestic video amp (LT1254) which is a quad amp. Other than that, all you need are (3) 2SC1815 NPN Transistors and a couple of resistors and capacitors. Good Luck:
(Note: the following information was gotten from bakuchikujuu's website http://babelfish.altavista.com/babelfish/t...FPCE_DuoRX.html I suggest you go to the site and read it. It's a whole new lesson in Engrish <-that's not a typo.


)

And I'll leave off by saying... and I quote...
"the brave figure of R-9 which starts projecting"


I hope this helps somebody...

[NFG]

The results of the new amp are quite obviously better than the old one.  Thanks for the comparison shots!  

Maybe it should be added to the wiki...  Hmmm...

[Endymion]

Incredible. Inspirational. I wish to subscribe to your newsletter, and will perform this mod at such time that comfortable and unsqueamish with adding homemade circuits. Which given my timetable should easily be sometime in the mid 25th century.

Or later this year.

Definite wiki material.

[acem77]

thanks bakuchikujuu big time for the eagle format file for the pcb board lay out.
i am going to have a few of these made i am sure the amp will work nice with the n64, and nes    my duo and super grafx will be very happy
futerlec has very good prices for pcb manufacturing
i used them for my 3do rgb pcbs

thank you!!!

[acem77]

Does any one have the full parts lists in english for this? hopefully the hard to find parts are substituted for easy to find ones? if so could it please
be posted here?
vkp_ashley if you have not already could you please check your pm.

thanks

[acem77]

i have been looking at the eagle pcb file and there seems to be some mistakes?
the trace from one side of the cap the sync signal goes nowhere?
i also see a lot paths that have no components when compared to the picture.
any one have plans to translate this from japanese.
it would be nice to have a bill of material and another drawing showing the values
of the components mounted on the board.

[Drewman21]

Acem77 if you do get a kit together please let me know.  I am looking to get my TG16 going here and would want to put in a RGB amp.  PM me if you ever get one going. Thanks man!

[viletim]

acem77,

If you're in the mood to experement then try this circuit. It's extremely crude but if bakuchikujuu's info is accurate then it may just work.

Q1 is a NPN darlington transistor, MPSA13 or similar. If you don't have one then make one from two normal NPN transistors (2n3904, BC548,etc) connected as shown.

D1 and D2  are just standard signal diodes 1n4148 or similar.

[raisinland]

I took a look for a US source for the NJM2267 chips and mouser carries the NJM2267D dip package. (43 cents each, not bad)

[NeWmAn]

If anyone wants to try a PCE video amp based on a real video op-amp (like the LT6552 that bakuchikujuu suuggested or the MAX4451 which is available from Futurlec) then I'd recommend a differential amp configuration. These opamps don't like their input to get any higher than Vcc-2v so you'd have to divide the input by two and double the gain to four (from the usual two). The negative input is to null the huge DC offset (4.2v!!) of the input signal.

Code Select Expand

.+5v
. |
. R
. R<---RRR-+--RRR--+
. R        |       |
. |        | |\    |
.---GND    +-|-\   |   75
.            |  >--+--RRR--o video out
.Vid --RRR-+-|+/
.in        | |/
.          R
.          R
.          R
.          |
.         ---GND  

Can the Vidin input of this circuit be connected directly to the PCE or does it need the pre-amp section?
Also what are the recommended values for the trimmer and the unmarked resistors?
 

[viletim]

Here's a full circuit with component values. This hasn't been tested at all but it should work in theory.

Three opamps in differential config. Non inverting gain = 3.5 (video signal), Inverting gain = 2.5 (offset subtract). Input is divided by two by R5/R6 to keep it away from the positive supply rail. A suitable opamp must be fast (-3dB point at least 30MHz) and able to run off just 5 volts. I think all the opamps mentioned in this thread so far are ok.

Edit: And I should mention, if you're two dual opamps and have one left over then, to prevent oscillation, connect a 10k resistor between the output and negative input.

[NeWmAn]

Thanks Viletim!

P.S. what program did you use to draw that schematic?  

[viletim]

what program did you use to draw that schematic?

Qt-BSch

[Segasonicfan]

There are also super super simple 3 channel video amp circuits you can probably use for this.  I used one as an RGB amp for the Laseractive.  Intersil provides a large variety of them.  

-Segasonicfan

[NeWmAn]

I've finally built Viletim's circuit and these are the results (please excuse me for the poor quality of the photos  

BEFORE - AFTER

Mesopotamia:  (look at the columns and the clouds)



Burning Fight: (Background is not so dark anymore)
Konami Logo:



Dragon Spirit: (Title screen background is a shade of gray/green instead of black)



Fantasy Zone: (Look at the color of the mountains in the background)

There are also super super simple 3 channel video amp circuits you can probably use for this.  I used one as an RGB amp for the Laseractive.  Intersil provides a large variety of them. 

-Segasonicfan

I could have used a 4 in 1 op-amp, but the most annoying part of this circuit is the resistor network <_<


Thanks again to Viletim!

[viletim]

Looks good. I'm preparing some stuff for the wiki at the moment and will add this too.

Segasonicfan,
Yeah, a fixed gain, special purpose video amp would reduce the component count but then the disign would be limited to that specific chip. Just like New Japan Radio parts (what bakuchikujuu used) are unavailable outside of japan, Intersil parts arn't available outside of the USA. That's why I think it's best to use generic parts whenever possible.

[strider77]

I really want one of these AMPs for my Turbo Duo. Would anyone be willing to construct one for me? I will gladly pay for it and the labor.

[budo-ka]

Nice work.
it would be interesting to open a pc engine cdrom adaptor to see how they manage to amplifie the RGB or video signal coming from the main IC (and its rear plug). I'm sure they just used a couple of npn transistors... without the use any other IC.

[NFG]

Why would it have any kind of RGB amp?  There's no additional video processor like the 32X, it's just a storage device.  All the graphics and video generation is still handled by the PCEngine, and none of the CD ROM systems offered RGB output. 

You will find an AV booster since the CD ROM attachments had additional AV outputs, and they mixed the audio from the system with the additional sounds generated by the CD, but the video generation was completely untouched.