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Nebula

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As some of you probably already know, there is a graphics problem on certain hardware in Taito's F3 system.

Let's put the situation in context:
Some of the first pcbs of the F3 system, specifically those that came out between 1992 and 1994, were designed as single-pcb and there were two different revisions of them. As @undamned called on his blog:
http://therealundamned.blogspot.com/2009/08/taito-f3-pcb-101.html
  • First revision using orange components (early games): Ring Rage, Arabian Magic, Riding Fight, Grid Seeker, (Taito Cup Finals?)
arabianmagic.jpg

  • Second revision using white components (93-94 games): Taito Cup Finals, Top Ranking Stars, Prime Time Fighter, RayForce, Super Cup Finals (also have additional rom space)
rayforce.jpg



However, before transitioning to the motherboard and cartridge model, some of the latest games were released using the first revision (orange components) of the system, reused or converted to run some of the games originally designed to run on pcbs of the second revision (white components). You could say they were factory-conversions. The games that I've been able to identify in which this was done are:
  • Gunlock
  • Super Taito Cup Finals
  • Light Bringer / Dungeon Magic

expandpcb.png

To do this, Taito used an “Expand PCB” mounted onto original revision 1 board using two connectors on each edge of the board. This was done because we suppose that the original mask-roms of the games (arabian magic, Riding Fight ...) were not extracted from the pcb for reasons of saving time or money, and instead they used the "Expand PCB" to place the roms of the new "converted" games, as they didn't fit on the original board.
In addition there are several factory-patches made on the solder-side of all of them to cover some additional addressing that the old board (orange components) did not originally cover, but that the next version of the board (white components) does:

patches.png


So far so good, but it's well known that specifically these games using "expand pcb" have a problem of "color bleeding", in which it seems that there is a blur effect that goes from left to right, (and from bottom to top in gunlock, vertical game), a problem that doesn't occur in other games like grid seeker, arabian magic ... using exactly the same base hardware (weird?!). (More info here: https://shmups.system11.org/viewtopic.php?f=6&t=50619):

5WgtZsEl.jpg


aZZcbtFl.jpg
6MAxIwMl.jpg


This made me suspect that there must be some differences between the components used in pcb of each game, apart from the "Expand PCB", and that difference must be located in the analog video output stage, since the effect is visible in every single layer of graphics in the game: both sprites, text and backgrounds.

Comparing the pcb with the Grid Seeker one, I found several amplifier transistors had been replaced by jumpers, and some resistors had been removed (or not installed at all), as well as other transistors replaced by a different model.

Super Cup Finals:
components1.png

Grid Seeker:
components2.png

Components originally installed in Grid Seeker:
  • 3 x A1015 (Toshiba transistor) placed at TR1, TR2 and TR3
  • 3 x C1815 (Toshiba transistor) placed at TR4, TR5 and TR6
  • 3 x 2K Ohm resistors placed at R32, R33 and R34
So, I didn't hesitate and looking those “correct” references on my Grid Seeker pcb, I purchased the components.
After waiting over a month (ughh) for them to arrive to my door, I finally had them available to try.
Obviously, instead of testing that in Gunlock's pcb, a Super Taito Cup Finals with “Expand PCB” was the first pcb chosen to test whether using the correct components that were originally mounted on the first F3 boards would make the annoying bleeding effect disappear...:

componentsremoved.png

New components installed:
componentsinstalled.png

Once the "original" components had been installed (like the ones we saw in the Grid Seeker), let's see if the result was successful:

g81Ygwal.jpg


YAAY!

Seeing that was successful on Super Cup Finals pcb, I decided to do it also in Gunlock pcb and results are obviously the same and lot better than the previous one:

trMT6fpl.jpg
TRaMsJPl.jpg


Sharp and colorful image as any other F3 game!


I do not know if this change of components was made for compatibility with European or USA chassis or if there was simply no stock of those components and a cheaper workaround was carried out.


If you have any of the pcbs involved, don't hesitate to fix it!



PD: I also made a YouTube video explaining this (only in Spanish, sorry :rolleyes: )

 

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Killingbeans

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Gunlock running on my Egret II with no color bleeding :D

Gunlock_Egret_ii.jpg


Not my best soldering job ever. All of the components has a pesky connection to a ground plane, so don't do this unless you have a good soldering iron and/or the skills not to fuck it up;)
 

Killingbeans

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Wadda ya mean? There's a kick harness underneath, but it's not connected to anything at the moment :)
 

Mrhide

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he's probably talking about the alignment, which should be like so:

IMG_0918s.jpg
 

djsheep

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Fantastic investigative work.
 

Killingbeans

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he's probably talking about the alignment, which should be like so:

Ahh I see. It was like that when I got the cab. I'm not complaining. I actually prefer it that way.

It also has a 7th hole that is blanked, so you can set up for both jamma, neo geo and 6-button fighters. In many ways I'm a purist, but not when it comes to control panels :whistling:

EDIT: When I do a picture search for Egret II, I get a mix of both alignments. Maybe non of them are more "official" than the other?
 
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Nebula

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Gunlock running on my Egret II with no color bleeding :D

Gunlock_Egret_ii.jpg


Not my best soldering job ever. All of the components has a pesky connection to a ground plane, so don't do this unless you have a good soldering iron and/or the skills not to fuck it up;)

Congrats! enjoy that masterpiece in its full glory
 

Mrhide

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EDIT: When I do a picture search for Egret II, I get a mix of both alignments. Maybe non of them are more "official" than the other?

You know what? I think you might be right! and looking at the manual, yours appears to be more like it than mine!

e2c.jpg
 

twistedsymphony

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the bottom row seems weird to me, button 4 should be slightly to the left of button 1, but instead it's between 1 and 2, it's like the button layout has been rotated 45 degrees counter clockwise.

Killingbeans, I'm not the most well versed in Egret II but It looks like you had a 4 button panel and someone added the bottom row, but not in the usual positions.

iSJvphKITcdarGHWfOZHO4sYYnBJQBk-bVHTlq-pjBeU_Khw3-jleYqxWaySrr3v7bhkveFi.jpg
 

Killingbeans

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Killingbeans, I'm not the most well versed in Egret II but It looks like you had a 4 button panel and someone added the bottom row, but not in the usual positions.

Possibly :)

This one from the Arcade Otaku wiki has exactly the same layout:
03_%282%29.jpg


Only difference is that I don't have the "Neo-Geo" buttons installed. Just a black plug.

BTW, sorry for hijacking the tread with all of this Egret II talk :D
 

Nebula

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Taken from the official part list of Egret 2, there are 4 types of CPOs:

  • Default one: 2L8B:

egr2_1.png


  • Optional ones, including 2L12B (and Mahjong and Spinners ones):
egr2_2.png



I have both 2L8B and 2L12B, and the one from @Killingbeans is definitely the factory 2L8B one (due to the curvature of the first row of buttons) but with the second row of buttons added later following the same curvature.

This is my 2L8B factory one:

IMG_9794.jpg
 
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Nebula

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nice work,
but the value of R32, R33, R34 is 2KΩ not 1KΩ.................
Thanks for the heads up! That was a typo. You can clearly see the resistor color bands as "red-black-red" on the new replacements.

First post edited to fix it.
 
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