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Old 14 August 2019, 16:54   #1
lost_lemming
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what's up with my 1081 monitor - not displaying all colours!

the 1081, the one with the green-screen button on the front. not to be confused with the 1084s !

I have recently bought a cable that is a 23pin to 8 pin din socket. It goes into the "TTL RGB" of the 1081 but this is all I get...



I tried with a compesit cable (RCA) and although it's very fizzy looking (as expected for comp) ALL the colours are there! (pictured below) Not sure if it's the cable, or the monitor.? any ideas? I tried with another A1200 and the same thing happens.



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Old 14 August 2019, 17:02   #2
Hewitson
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TTL RGB is a digital signal used on the C128, CGA IBM PC's, and several other machines. The Amiga outputs analog RGB, which is why you're missing colours.
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Old 14 August 2019, 18:38   #3
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The Amiga also outputs TTL RGB, but the important thing to understand here is, that most of the shades will be missing due to only two intensities per colour component being transmitted over TTL RGB.
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Old 14 August 2019, 21:04   #4
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Welcome to the wonderful world of 4-bit RGBI video: https://en.wikipedia.org/wiki/List_o...tes#4-bit_RGBI

A good question would be "Why on earth did Commodore include that utterly useless feature on the Amiga?"
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Old 14 August 2019, 23:47   #5
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ahh ok I see. that explains it thanks.

I have a 23pin for Amiga to male scart plug but sadly that whole scart thing on the back of my 1081 is dead for some reason so that's why I tried this TTL din one. I guess one day I'll have this monitor fixed properly.

The fuzzy comp out image isn't TOO bad... you can adjust the controls on the front and back to get it as good as possible but that RGB scart, I know for a fact would look way more crisp!
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Old 15 August 2019, 10:33   #6
demolition
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There might be a switch somewhere that needs to be toggled for SCART to work.
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Old 15 August 2019, 10:50   #7
lost_lemming
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Quote:
Originally Posted by demolition View Post
There might be a switch somewhere that needs to be toggled for SCART to work.
yeah tried all the buttons
All it shows is a sort of dark mustard yellow/green colour. with a faint horizontal line scrolling up the screen quickly. That was shown with 2 of my amiga's so I don't think it's them.

I know some one who can open it up and maybe fix it! I am very scared of CRT's! even when powered off.

Last edited by lost_lemming; 15 August 2019 at 11:10.
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Old 15 August 2019, 11:22   #8
Hewitson
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No need to be scared of a CRT if you've discharged it (several times) correctly. They can rebuild a charge if only discharged once. I've seen it happen!
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Old 15 August 2019, 11:47   #9
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Quote:
Originally Posted by Hewitson View Post
No need to be scared of a CRT if you've discharged it (several times) correctly. They can rebuild a charge if only discharged once. I've seen it happen!
Which is why I think it can be good for your health to be scared of CRTs. Do not open them up unless you know what you are doing.
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Old 15 August 2019, 16:29   #10
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Quote:
Originally Posted by lost_lemming View Post
yeah tried all the buttons
All it shows is a sort of dark mustard yellow/green colour. with a faint horizontal line scrolling up the screen quickly. That was shown with 2 of my amiga's so I don't think it's them.
Did you try an alternative SCART source? (DVD player etc). Some devices have problems with some Amiga SCART cables.
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Old 16 August 2019, 15:57   #11
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It's fixed! yes! CRT LIVES!

my father fixed it. now, let's try and get the technicals right...

I think it goes like this, the RGB input switch for it to turn on wasn't working because of .... there were 3 diodes for the red green and blue and the blue one had a different signal to the others. (something about ohmz resistance) cause he used the multi meter to check it.

he found the diode bit because he traced it back there from 3 or 4 transistors not switching on. It turn out it went back further to this vertical board sticking up off the main board and the fault was actually a chip (a chip which he didn't have a replacement for) So he did some work-around of a pin not being used (pin #3 I think) putting a little jumper wire over the chip, and now it works!!!

I think the faulty chip might have happened from a spike of current going into the RGB. not sure. Don't care anymore, it works now! no more fuzzy compisite image! ... well, actually it wasn't TOO fuzzy but smaller text suffered a bit. Nice and crisp now.
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Old 16 August 2019, 15:59   #12
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Quote:
Originally Posted by nogginthenog View Post
Did you try an alternative SCART source? (DVD player etc). Some devices have problems with some Amiga SCART cables.
No don't have any other scart source kicking around.
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Old 19 August 2019, 00:09   #13
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hmmm, no one cares it seems!


ANOTHER CRT MONITOR HAS JUST BEEN SAVED!
I hear all these horror stories of all CRT will eventually die out! well not if they're looked after properly! also, lots of them were made
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Old 19 August 2019, 03:34   #14
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Thumbs up

@ lost_lemming


congrats to your dad on getting your 1080 fixed! I still have 2 of them running in my mancave regularly still going strong
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Old 19 August 2019, 16:29   #15
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When you say your father fixed it by jumpering a chip on the raised daughter board, do you mean that you still use TTL RGB instead of Scart?
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Old 20 August 2019, 12:14   #16
lost_lemming
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Quote:
Originally Posted by idrougge View Post
When you say your father fixed it by jumpering a chip on the raised daughter board, do you mean that you still use TTL RGB instead of Scart?
no, The Analog RGB scart works now, that's what was fixed. The TTL still works though.
I'll ask him again the details but he said something like the chip had failed which meant the blue diode couldn't switch on, which leads to another switch to turn on another switch transistor and so forth. I don't get it myself, I thought it would just be duff solder joints coming loose on the scart socket. I probably would have tried to fix it with blue tak too haha.
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Old 20 August 2019, 17:08   #17
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I thought the daughter board was only responsible for TTL picture, hence my question.
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