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Offline tribzTopic starter

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SCART RGB Lead problem
« on: April 09, 2011, 09:31:32 AM »
Got my RGB scart lead today from Amigakit and was looking forward to some nice and clear screen Amiga goodness this morning. Unfortunately, I only get the below. It’s a bad picture I know but basically the screen is really black with lots of interference lines. Occasionally it drifts from being a terrible picture to just being a really bad picture.

I've tried the RGB and AV scart sockets on the LG telly. I'm pretty sure the monitor socket on the amiga's ok as when I bought it, it was demo'd to me connected to a multisync monitor and looked great.

Any ideas?

http://www.datacenta.it/Photo1.jpg

ETA http://www.datacenta.it/Photo2.jpg

Hooked it up to another LCD and get a washed out white picture with something just visible at the top. Think its either the cable or the connector but leaning towards the cable?
« Last Edit: April 09, 2011, 09:43:29 AM by tribz »
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #1 on: April 09, 2011, 10:31:53 AM »
Hiya Franko,

Thanks for that. I've got the hood open on each end. I dont know if this is relevant or not but I cant measure resistance on pin 8 whereas I can on pins 16 & 20.

I've been using this as a guide ...

http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_SCART/amiga_scart.html

I can measure the 75 and 330 ohms on pins 16 & 20 so that looks fine but like I say not the 1k on pin 8. I have to confess, I dont really know what that means and if thats good or bad!!

ETA the TV's are a 32" LG 32LG2100 and a 17" Vistron no name brand.
« Last Edit: April 09, 2011, 10:43:02 AM by tribz »
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #2 on: April 09, 2011, 10:44:49 AM »
How to I measure the voltage on the pins on my meter?

I'm a little wary of shorting something that damages my amiga.
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #3 on: April 09, 2011, 11:30:56 AM »
Thanks Franko,

I've removed those resisters and now get a picture like below ...

http://www.datacenta.it/Photo3.jpg

The horizontal banding isnt really there, thats the camera.

So its a better picture but still some ghosting. Also, its a 4m cable, maybe some signal degredation due to length? I'm thinking I might redo the whole cable. Maybe not today though. The sun is shining and that doesnt happen often :)
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #4 on: April 09, 2011, 02:06:11 PM »
Quote from: amigakit;630447
Modifying a perfectly good cable based on hear-say in this forum is not a wise thing to do.

Every Scart cable from us has been made to modern LCD TV standards and is fully wired.  The cable has been assembled correctly and has been Quality Tested before despatch to customer.  We test on a wide range of models and use a widely used schematic.

Forums can be a good source of information sometimes but it is better to consult with your dealer before resorting to modifying the product and jumping to conclusions that there is a fault in the product.


Hi Matthew?? I note the US numbers and if so, I didnt buy it from the US.

I dont think anyone has said as such that there is a fault in the cable.

It just doesnt work :-)

I have to take issue with it being a perfectly good cable otherwise it would work :-) I've also tried it on my 40" samsung and I couldnt get a viewable picture on that either. So thats 3 different brand LCD's. Not got a CRT to try it on but I to be honest I bought it for LCD compatibility. Like I put earlier, it might be the DB23 connector amiga side but I've seen that working fine connected to a monitor.

Anyway, I'm happy to cut the ends of and redo it. All part of the amiga fun and games.

Dont take it personally. I'm just getting the benefit of forum experience. Enyoy the sunshine and the rest of your weekend.
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #5 on: April 10, 2011, 09:36:01 AM »
Quote from: alexh;630582
You could try using the Composite video output as the sync for your RGB. See the Stedy diagram for info.


Hello Alex,

So which pin should I solder to where instead?

Thanks :)
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #6 on: April 10, 2011, 10:54:56 AM »
Quote from: alexh;630663
?? You linked to the diagram!

An RCA plug (which goes in the yellow RCA socket on the rear of the A1200) Wire it to pin 20 & pin 17 (disconnect whatever normally comes from 23-pin) as per the diagram.


Yes, but doesnt mean I understand it! :)

Just so I understand it, get a yellow RCA connector and solder it to pins 20 & 17 ... on the scart connector ?

Thanks
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #7 on: April 10, 2011, 10:56:15 AM »
Quote from: Franko;630660
Pin 20 on The SCART Connector for Composite & Pin 18 for its Earth/GND.... :)


Sorry Franko, I'm a bit confused. I know this is probably simple but which pin on the Db23 to which one on the scart?

Thanks :)
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #8 on: April 10, 2011, 11:22:15 AM »
Quote from: Franko;630675
Hi Tribz... :)

To wire up the composite video connector of the Amiga like AlexH is advising you... :)

You need to connect the central wire of the Composite Video Phono cable to PIN 20 on the SCART connector and the outer sheilding/earth wire of the composite video phono cable to PIN 17 of the SCART connector... :)

Hope that's a wee bit more simpler to understand... :)


Thanks, much appreciated haha

Ok, I've done that and now at least I get a picture on AV2 but its a composite one

http://www.datacenta.it/Photo4.jpg

On AV1/RGB, its more stable at least but its still quite out.

http://www.datacenta.it/Photo5.jpg
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #9 on: April 10, 2011, 01:27:59 PM »
Think I'm there or thereabouts now!

http://www.datacenta.it/Photo6.jpg

I started again and used this http://wiki.classicamiga.com/Amiga_RGB_to_Scart_lead

Would I be right in thinking this isnt 'fully wired'? Picture is miles better than composite with just some ghosting
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #10 on: April 10, 2011, 01:30:04 PM »
Quote from: Franko;630687


AV1 SCART sockets are usually RGB enabled and from the pic you've just posted it looks to me like it's trying to display both a Composite and RGB signal at the same time... :(
Hence the "double" image your getting... :(

That's what the voltages that get applied to pins 16 & 8 on the Scart socket are for, to tell your TV to switch to RGB display mode and not display the Composite picture. It looks like your TV is not switching to RGB mode and instead trying to display a composite and RGB picture at the same time... :(

It could be one of many different reasons for this but most likely it's the voltages going to pins 16 & 8 on the Scart connector that are incorrect and thus your TV is not switching to RGB mode... :(


Interesting, I wonder if disconnecting composite wire will remove the little remaining ghosting. I'll try it now!
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #11 on: April 10, 2011, 01:31:34 PM »
Quote from: AppleHammer;630691
Agreed - this is why I think we need to see some voltage measurements on the cable, if possible.  I think the in-line resistors are there for the purpose of presenting the correct mode-switching voltages to the LCD TV.

AH.


I think your right. I've got a meter but I dont really know how to take a reading. I've been a bit wary incase I short something.

I've got no resisters attached in the now working cable.
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #12 on: April 10, 2011, 01:32:49 PM »
Quote from: utri007;630699
Hi

One of my scart cabels doesn't work correcly with my lcd tv.

Picture is light, I mean that it is hardly visible, it is like a ghost. No dark colours it is like contrast would be 0.

What is wrong with it? Problem can't be TV, it is proven to work with amiga.


Is it like this ?

http://www.datacenta.it/Photo2.jpg
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #13 on: April 10, 2011, 02:52:45 PM »
Quote from: tribz;630709
Interesting, I wonder if disconnecting composite wire will remove the little remaining ghosting. I'll try it now!

The remaining ghosting was caused by having the L/R rca being wired at the DB23 end. Must have been some interference. I've connected them in at the SCART end and no ghosting at all now, great picture.

http://www.datacenta.it/Photo7.jpg (phone cam not doing it justice)

Thanks for all the help. This is a milestone day for my miggy. Everything done, time to play.
« Last Edit: April 10, 2011, 02:57:53 PM by tribz »
 

Offline tribzTopic starter

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Re: SCART RGB Lead problem
« Reply #14 on: April 10, 2011, 02:59:33 PM »
Quote from: utri007;630718
Exactly same

I could try to fix this myself, but I'm not experienced to soldering.

So I would appreciate if I could get good instructions what to try.


The thing I've learned this weekend is there are about a gazzilion ways to wire up a scart lead. This is the one that worked for me ...

http://wiki.classicamiga.com/Amiga_RGB_to_Scart_lead