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Can anyone improve the rgb output on my duo?

Started by incrediblehark, 12/30/2011, 12:00 PM

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incrediblehark

Ok, so here are pictures of the two systems. RGB Output is using the same cable, on the same display, a Sony PVM Monitor. Both were tested using PC Genjin 2.

Here is the PC Engine:

IMG

And this is the Turbo Duo:

IMG

As you can see there is hardly any difference, both systems have a great picture, but the Duo does have the more noticeable vertical lines. It probably sounds like I'm being extremely anal about this, its just that I would like to use the Duo as my everyday system but if the PC Engine has the better picture I'll just stick with that one.

thesteve

wow those are narrow lines.
my tests involved wider lines that were less distinct.
the pic looks a bit weak on the duo as well, that deserves investigation

incrediblehark

Thats what I meant when I was saying the picture was brighter on the pc engine. well the pics speak for themselves! :)

thesteve

i just did 2 RGB mods
1 my black duo
2 an IFU
screen shot
RGBModTest.webp
the amp
RGBModCircuit.gif
installed
RGBModInstalled.jpg

Bernie

Nice job Steve!  Hopefully this is what Beemer does to mine.  :)

incrediblehark

Very nice! that's a pretty small amp too. so you're not getting any of the lines like mine? for me its most noticeable on solid colored backgrounds like blue or green.

thesteve

#56
i get a small amount on black and blue, but nothing close to as bad as yours.
take a volt meter and compare the dc voltages on the inputs to the amp.
if your voltages are lower on the duo it could mean a bad input cap on the amp.

PS you have the same duo as me
if you havent had a full cap change its highly recommended and does improve performance.

HercTNT

Steve, that is outstanding picture quality on that. And i thought mine looked pretty good. I dont get any of the lines that incredibleshark has, but i do have some jailbars only when black is showing. those jailbars exist though all the time not matter what i'm doing. i think my lcd is just crap.  Will putting that 220uf cap on that you mentioned help regardless of what rgb mod you have?  I have 1 uf ceramic caps, you recommend putting them from pins 41,42, and 43 to ground?

thesteve

pins 41 and 42 are ground
so the cap from 42 to 43, and if you bridge 41 to 42 no prob
yes its an improvement to any (even composite)

HercTNT

the ceramic caps i have are not polarized so i would solder one leg on 42 and one on 43 and i would be good to go eh?  I know i'm just repeating what you just siad, but i'm being extra careful. you mention a 220uf cap on c961 as well. what exactly does that do?

thesteve

yes thats right
both caps reduce the noise on the videoprocessor

incrediblehark

Quote from: thesteve on 02/03/2012, 08:27 PMpins 41 and 42 are ground
so the cap from 42 to 43, and if you bridge 41 to 42 no prob
yes its an improvement to any (even composite)
Is that on the HuC6260?

Quote from: thesteve on 02/03/2012, 02:42 PMPS you have the same duo as me
if you havent had a full cap change its highly recommended and does improve performance.
I may have to go that route but would feel more comfortable having someone else do the cap replacement just because its a US Duo and I've had a bad luck with these systems in the past

BlueBMW

Ahh, if you haven't had caps, that may very well be your issue to begin with! :D
[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc

thesteve


HercTNT

I'm gonna give this a try as soon as i get a bit that will open my duo. I heard i could make one by melting the end of a bic pen, but i dont have one of those either :)

BlueBMW

If you're just opening it the one time, order one of those cheap china security bits (as they're good for maybe one use anyways) and get some replacement screws.  :D

Melting the end of a bic pen?  seems unlikely that it'd work.  The screws in Duos are usually tighter than darnit if they've never been out before.
[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc

HercTNT

I saw the bic pen thing on another guys site. He claims it works, i dont know, i have never done it. My duo has been modded before so the screws might not be that bad. I tried to order the security bit, waited 3 weeks and they sent me the wrong one.

ApolloBoy

The pen trick never worked for me, I'd just invest the money in a good gamebit.
IMG

HercTNT

Steve, c961 in my unit has a 10uf 50v cap in it.  I need to match the voltage do i not. My 220uf caps are only 25v.

BlueBMW

Quote from: HercTNT on 02/05/2012, 10:18 PMSteve, c961 in my unit has a 10uf 50v cap in it.  I need to match the voltage do i not. My 220uf caps are only 25v. 
Has that cap been replaced by someone?  The only 50v cap I know of in the duo is the 1uf one by the cd drive connectors...
[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc

HercTNT

yes it was recapped when i bought it. its a doujidance dou-r.

thesteve

it should be a 16V cap.
anything 16V or more is good.(6V would be fine for that cap)

HercTNT

Ok everyone, I followed steve's instructions and installed a 1uf ceramic cap on pins 42 &43 of the huc6260 chip. Then I installed a 220uf cap on c961 that sits directly below were you put the ceramic cap. After installing the two caps the improvement on the composite video is the most dramatic for me. The improvement on the rgb video is still very noticeable. Thanks to all the advice from everyone in this thread, and special thanks to steve, my output is alot better. It was really good before.  Dont ask for screens, as i have stated before my camera sucks. Lets just say that making the adjustments to your duo is worth it.

thesteve

C961 that sits directly below where you put the HU-Card

fixed it for ya

HercTNT

LOL, yea thats what i meant to say. thanks.

incrediblehark

Still have to try caps on pins 42 and 43 good to hear it worked for you!

thesteve

1 cap between 42 and 43
the shorter the wires the better

HercTNT

#77
shorter wires the better.........grrrr. Now i gotta do the ceramic cap again. I left the wires long cause i was having a hard time holding the cap.

Edit: Ok, I scared the hell outta myself when i almost pulled a trace removing the ceramic cap. I fixed it, shortened the wires on the cap to about 3/8" and resoldered. so far so good.

PunkCryborg

I can confirm that I too have jailbars with my RGB modded duo from DoujinDance on ebay. The colors and picture looks great but yeah you do notice the faint jailbars on lighter solid color screens.

incrediblehark

I still haven't tried the extra capping between 42 and 43, every time i open the system the region switch wires pull apart and it annoys me so I've been putting it off.

incrediblehark

Is the cap on pins 42/43 supposed to make my picture brighter? I have been messing around and got the picture way too bright, colors washed out, but no interference/jailbars. I tried to since recreate that or tone it down using a different cap but no luck. Looks like I may just need the full cap replacement next.

thesteve

it will make the pic slightly brighter, as it stabilizes the output stage of the chip.
odds are you bridged it to 5V as it should be slightly below 5V

incrediblehark

ok i thought i must have screwed something up when it was like that. yeah after i rechecked my soldering there wasn;t much change in picture.

HercTNT

neither cap by themselves made a huge difference for me, but both of them made a noticable difference.

Ravij

Hi everyone.

I finally got round to starting an RGB mod on my PC Engine DUO, well actually I did a 5 Pin DIN to 8 Pin DIN swap a year or 2 ago - may be more (this mod has been in the works for 10 years I'm sure  :oops:)

I made the RGB 8 Pin to Euro SCART yesterday,

And today wired the HU6260 to 3 RGB wires, and then wired the backside of the 8 Pin DIN Socket to 3 more RGB wires, the idea being the RGB amp goes in the middle of the 2 lots of wires.

Shielded cables used all the way - I only want to do this once, and do it right!

As soldering onto the HU chip took a while (i.e. bl***y difficult) - I left things at that.

Except I couldn't resist joining up the 2 internal sets of RGB wires that were meant to be the in / out from the yet to be made RGB amp (which will be NJM2267 based) :lol:

The picture was actually pretty good, not dark in any way, but I did notice jailbars on large areas of solid colour. I need to put a switch in my SCART so I can flip quickly from C-VIDEO and RGB to do a really good back to back comparison of colours, so I'll pass on that for now.

Now the NJM2267 RGB amp may well reduce the jailbar effect, but if there is anything else worth doing now, I'll give it a go. Like I said, I want to do this to the absolute best quality I can, even if the improvements are minimal.

From what I understand, its possible to stick a Capacitor across the power input of the HU chip, to smooth out its power feed?

I think this is what is being suggested here http://baku.homeunix.net/RGB/PCE_DuoRX/PCE_DuoRX.html#add-passcon - any Japanese speakers please translate!

Also - someone suggested a CAP mod in this thread too.

Could anyone (preferably someone who has actually done it) let me know what CAPs I need, and between where?

Any other worthwhile tweeks, please let me know.

thanks!

thesteve

just from the pic's in the jap thread, i can tell you this thread is the english equiv.
the pins are the same.
the shorter the leads the better. (ceramic chip across the pins of the chip is ideal)

Ravij

Quote from: thesteve on 06/08/2012, 10:06 PMjust from the pic's in the jap thread, i can tell you this thread is the english equiv.
the pins are the same.
the shorter the leads the better. (ceramic chip across the pins of the chip is ideal)
OK - so what CAP across what Pins?

thesteve

i have some 22uf size 1206 SMD ceramic caps that work great.
you could get away with about anything (preferably ceramic or tantalum)

Ravij

Quote from: thesteve on 06/09/2012, 01:25 AMi have some 22uf size 1206 SMD ceramic caps that work great.
you could get away with about anything (preferably ceramic or tantalum)
Sorry if I'm being dumb - but across what should the CAPs be placed?

This thread mentions HU6260 PINs 41 and 42 as ground, but here it says they are +5Volts:

http://gamesx.com/wiki/doku.php?id=schematics:hu6260_netlist

thesteve

now i will have to look again. (5V it is) doesnt matter with ceramics
pin43 is the one you care about.

Ravij

#90
Quote from: thesteve on 01/28/2012, 02:48 AMsolved


to solve jail-bar issue on rgb modded system replace capacitor C961 10uf with 100uf tant or 220uf aluminum.
the cap is from hu6260 pin43 to ground.
C142 on the TG16
Just swapped the C961 10uf SMD cap for a 100 uf SMD cap. Jailbars I was seeing on PC Genjin 2 in the  blue areas of the sky have gone.

Thanks Steve!

I would recommend  everyone to try this first, as it's so easy to swap.

Ravij

Another quick question - where is the best place to tap 5 volts to power my NJM based amp? I'm going to stick the amp PCB over the HU card slot, as there is plenty of space there, and no heat sources.

ApolloBoy

Quote from: Ravij on 06/10/2012, 11:38 AMAnother quick question - where is the best place to tap 5 volts to power my NJM based amp? I'm going to stick the amp PCB over the HU card slot, as there is plenty of space there, and no heat sources.
Since you'll be sticking it over the HuCard slot, pin 38 on the slot would be an ideal place to grab 5V.
IMG

incrediblehark

Ravij you were using the same test game as me :) I still need to get back in my Duo and see if I can finish cleaning up the picture, maybe tomorrow

gtsamour

#94
I've done the RGB mod on two TG-16 (US models), a Core II, a Super Grafx and last week on a PCEngine DUO. Ι used the same amp on all of them (made them myself according to the schemtics of the good amplifier https://www.pcengine-fx.com/forums/index.php?topic=9299.0) and all capacitors were replaced with fresh ones on all of them (total recap). I also own a DUO-R that was bought already modded for RGB.

The DUO has by far the worst jailbars problem of all...
I noticed that if I use the non amplified sync signal tapped from the chip instead of amplifying it too, the bars are less obvious (i'm reffering to the DUO only)... I'm using bikuriman world as a test cartridge, the bars are very obvious on the blue sky at the begining of the game.

gtsamour

#95
Quote from: thesteve on 01/28/2012, 02:48 AMsolved


to solve jail-bar issue on rgb modded system replace capacitor C961 10uf with 100uf tant or 220uf aluminum.
the cap is from hu6260 pin43 to ground.
C142 on the TG16
When you say "220uf aluminum" do you mean electrolytic 220uF capacitor?
What voltage should someone get for the 100uF tantalum capacitor?

incrediblehark

you should be able to use a 16v, but I don't think higher voltages make a difference if you can only find ones rated higher

thesteve

i used 100uf 16V tant
the circuit is about 4V

gtsamour

#98
Do the tantalum caps have polarity like the electrolytic ones? From pictures on google i see they have a stripe, probably the positive pole?

thesteve

correct the stripe is positive on tantalum.