Re: [ukvac] [tech] Colour Bleeding fix - How to ?
>In October 2001 there was an excellent thread about 'colour bleeding'
where >Dave Roberts gave some very in depth information on how to fix this
problem.
>
>If I remember, at the time some kind of diagram of the circuit was
requested. >Is anyone able to supply one?
Seeing as no-one has stepped forward, since this was first asked at the
weekend, it looks like no-one has tried this yet. Assuming that this is
because I was a bit vague in my description of the circuit, then here is
a bit more info. I'm not promising it's a perfect workable solution, as
I've only spent a couple of minutes on it but it should get you pretty
close to what is needed.
Firstly, get yourself a copy of the schematics for a Hantarex Polo
monitor, (they're out there on the web somewhere). Take a look at the
three RGB input sections, these are emitter follower video buffers.
All you really need to do is copy these, and throw a couple of
resistors on the outputs.
Looking at the red channel, you will need to build a duplicate citcuit
comprising of D146, C131, T103, and R136,7,8. Where R139 is connected
to the transistor you'll need to connect a few extra resistors as shown
in the ascii diagram below (please engage fixed pitch font now!)
(Transistor)
|
|
| | 100 ohms
| |
| ____
+--|____|---- To scart cable.
| 47 ohms
| |
| | 47 ohms
|
-+- gnd
There you go, one video buffer. Connect to the 12v supply on your
Supergun and add a 470uF electrolytic and a 0.1uF ceramic capacitor
across the supply rails close to the transistor, to provide some
local supply decoupling.
Repeat three times and you should be able to get a nice clear
picture on your scart monitor.
If anyone does try this, then feel free to email me direct with any
questions/problems with the circuit. Of course if it works perfectly
first time, then brag about it on the list ;-)
Dave.
DATA Imported from archives: originally posted by Dave Roberts (daverob@cwcom.net)
