BBC micro RGB to scart problems (help/ suggestions)

discuss both original and modern hardware for the bbc micro/electron
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rph
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BBC micro RGB to scart problems (help/ suggestions)

Post by rph » Wed Jun 05, 2019 5:17 pm

Just got a bbc micro for my 42nd birthday, I've tried rgb to scart lead with my bbc on the family tv and it works fine. I've bought a small 4:3 samsung tv to use for this but when I plug it in the screen is black and the text start up is very dark grey, can barely see it. Do you have any idea what is going on? I've checked the scart on this tv running from a DVD player and it's fine. Am I needing to get a different tv and if so any suggestions, as I don't want to be in the same boat again.
Many thanks

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1024MAK
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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by 1024MAK » Wed Jun 05, 2019 6:45 pm

Hello and welcome to our forum :D

Does the TV have any menu or remote control options/selections to manually select RGB SCART mode?

The problem is likely to be that the TV SCART input is defaulting to composite video and not automatically switching to RGB mode. There are two control inputs on the SCART connector to control if composite video is used or RGB, and to control if the SCART input is active, if the picture is 4:3 or 16:9 aspect ratio.

You may ask why it works in one TV, but not on another. This is often due to some TV designs working to the current specifications, but others being more lenient.

Which SCART lead do you have?

Mark
Last edited by 1024MAK on Wed Jun 05, 2019 6:46 pm, edited 1 time in total.

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rph » Wed Jun 05, 2019 8:58 pm

Hi thanks for that. The cable is:
https://www.ebay.co.uk/itm/250877464070?ul_noapp=true
Have chatted to the guy who sold it to me and it seems the tv I bought is the problem. There is only 1 scart socket and there are no options in the menu to change any of the settings. I'm thinking I might have to sell it on and get some other tv. Gutted as I'm dying to get coding!

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1024MAK
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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by 1024MAK » Wed Jun 05, 2019 9:00 pm

Are you any good with a soldering iron?

Mark

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rph » Wed Jun 05, 2019 10:32 pm

How come? On the TV or cable?

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by IanS » Wed Jun 05, 2019 11:58 pm

I suspect he's refering to the cable. It should be possible to feed a signal from the beeb to the tv to make it switch to RGB mode.
A lot of cables use a simple diode and capacitor in the scart connector to generate the switching signal from the sync connection, but it's not always reliable. If there is a spare wire in the cable, you can feed +5V from the beeb into the tv to switch it into RGB mode.
If you can, open the scart connector and post some close-up pictures of the inside.

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by tricky » Thu Jun 06, 2019 7:43 am

Welcome, we had an old TV where the channels before 1 were the sockets on the TV, although I guess yours has a "source" button and you have tried it. Have you googled for an engineering menu?

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rmbrowngr » Thu Jun 06, 2019 12:26 pm

Maybe if you tell us the make\model of tv we can check the manual (if available online) how to enable RGB on the Scart socket. I think on Samsung TV there is a RGB selection item on the settings menu.

It's good pointer for me to check now as I want to buy a new TV\monitor for my Acorn machines and dump my old Sony CRT portal TV (and save some space for more Acorns to grow).
Richard B
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BBC B+ 64K (128K upgraded) with Duel OS, Raspberry Pi and Gotek.

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by 1024MAK » Thu Jun 06, 2019 12:41 pm

RetroComputerShack Acorn BBC SCART lead as typically supplied:Image

RetroComputerShack Acorn BBC SCART lead with 12V battery:Image

On some TVs, they require a voltage on pin 8 of the SCART lead to tell them to switch to RGB video mode. Further, there are two voltage ranges. The first voltage range is +5V to +8V, this switches to 16:9 aspect ratio (where available). The second voltage range is +9.5V to +12V, this switches to 4:3 aspect ratio (where available).

So for test purposes, you can try connecting a 12V battery between SCART plug pin 8 (positive) and pin 14 (negative) and see if that works. If you don't have a suitable 12V battery, a fresh alkaline 9V PP3 should do.

If that works, you can also try a 6V battery. If the results are acceptable using a 6V battery, then instead of a battery, remove the test wiring. Locate the resistor that is connected to pin 16. On the side of this resistor that is connected to the wiring coming from the DIN plug, carefully connect another wire to this point. The other end then needs connecting to pin 8 on the SCART plug.

If using a 12V worked, but using a 6V battery did not work, then you will either need a suitable battery for long term use, or better still, a regulated 12V PSU. Note that it is best if the PSU is double insulated and does not have a earth pin. Alternatively, if you obtain a suitable plug to fit the BBC computer external DC power output socket, you can obtain a +12V supply from here. But with this, include a 100Ω in the positive wire (there is no need for a 0V/GND wire).

I hope this helps :D

Mark
Attachments
RetroComputerShack Acorn BBC SCART lead with 12V battery.png
RetroComputerShack Acorn BBC SCART lead with 12V battery
RetroComputerShack Acorn BBC SCART lead.png
RetroComputerShack Acorn BBC SCART lead as typically supplied

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rph

Post by rph » Thu Jun 06, 2019 1:50 pm

Thanks for this, the model is: lw15e23 samsung
Have gone through the .pdf manual and no mention. Have looked through menu again and no luck.
The rewiring looks a bit beyond me but thank you

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by topcat96 » Thu Jun 06, 2019 2:14 pm

Some televisions require you to select RGB mode as the input for the SCART, because the SCART can transmit other video formats besides RGB, including composite video, s-video and component video. So you may need to select the correct input using the remote control. This is usually labelled as "input select" on the remote control, and you need to keep pressing this button until you get a colour image.
Image

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rmbrowngr » Thu Jun 06, 2019 2:15 pm

Looked at the manual and I didn't see something for RGB selection per source. Might be worth trying some of the things suggest in this page https://www.retrogamingcables.co.uk/tro ... art-cables.
Richard B
Acorn Electrons issue 4 and 6, MRB, Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi, GoSDC MBE.
BBC B+ 64K (128K upgraded) with Duel OS, Raspberry Pi and Gotek.

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Re: rph

Post by 1024MAK » Thu Jun 06, 2019 5:01 pm

rph wrote:
Thu Jun 06, 2019 1:50 pm
Thanks for this, the model is: lw15e23 samsung
Have gone through the .pdf manual and no mention. Have looked through menu again and no luck.
The rewiring looks a bit beyond me but thank you
If soldering is not your thing, for testing, you can use leads with small croc clips at each end. Then for a permanent job, either find someone locally to help you, or ask nicely on here.

But the first step is to find out if my suspicions are correct.

Mark

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rph » Sat Jun 08, 2019 9:35 pm

Oh my. Well I drove for an hour to pick up a CRT only to find that there was no remote so there was no way to set it to scart, then I sourced a monitor off my dad, and bought a scart to hdmi upscaler, but now i've set it up I've gone through all the settings and there is no way to adjust the screen so it is central and not distorted (I can't have that!). I've been at it for hours. So feels like I'm going to have to buy a second hand tv that has hdmi or/ and scart. Then if it works set the beeb up to scart and my PI up to hdmi. Wow this has turned into quite a mission all to show my daughter how great Chuckie Egg is as a game and to get some practice in assembly language coding to help me teach a level!


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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by daveejhitchins » Sun Jun 09, 2019 8:11 am

rph wrote:
Sat Jun 08, 2019 9:35 pm
Oh my. Well I drove for an hour to pick up a CRT only to find that there was no remote so there was no way to set it to scart, then I sourced a monitor off my dad, and bought a scart to hdmi upscaler, but now i've set it up I've gone through all the settings and there is no way to adjust the screen so it is central and not distorted (I can't have that!). I've been at it for hours. So feels like I'm going to have to buy a second hand tv that has hdmi or/ and scart. Then if it works set the beeb up to scart and my PI up to hdmi. Wow this has turned into quite a mission all to show my daughter how great Chuckie Egg is as a game and to get some practice in assembly language coding to help me teach a level!
Can't you find a One-For-All remote? They cover most of the CRT TVs that were around and are usually very low prices these days.

Dave H :D

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by tricky » Sun Jun 09, 2019 8:57 am

I guess you have tried any button combinations/the manual. I have six CRTs that I take to shows and all have remotes, but also a way to change source via button combinations, usually via a menu.

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by 0xC0DE » Sun Jun 09, 2019 9:15 am

daveejhitchins wrote:
Sun Jun 09, 2019 8:11 am
rph wrote:
Sat Jun 08, 2019 9:35 pm
Oh my. Well I drove for an hour to pick up a CRT only to find that there was no remote so there was no way to set it to scart, then I sourced a monitor off my dad, and bought a scart to hdmi upscaler, but now i've set it up I've gone through all the settings and there is no way to adjust the screen so it is central and not distorted (I can't have that!). I've been at it for hours. So feels like I'm going to have to buy a second hand tv that has hdmi or/ and scart. Then if it works set the beeb up to scart and my PI up to hdmi. Wow this has turned into quite a mission all to show my daughter how great Chuckie Egg is as a game and to get some practice in assembly language coding to help me teach a level!
Can't you find a One-For-All remote? They cover most of the CRT TVs that were around and are usually very low prices these days.

Dave H :D
If you happen to have a smartphone with IR blaster (I still do) there are some great universal remote apps. I am using the irplus app with an old TV for retro gaming.
0xC0DE
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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by rph » Sun Jun 09, 2019 9:32 am

Success!
Beeb - RGB to scart, to hdmi converter, to VGA converter - old 4:3 LCD monitor. It was that easy...
Thanks for all the help guys

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Re: BBC micro RGB to scart problems (help/ suggestions)

Post by daveejhitchins » Sun Jun 09, 2019 11:50 am

rph wrote:
Sun Jun 09, 2019 9:32 am
Success!
Beeb - RGB to scart, to hdmi converter, to VGA converter - old 4:3 LCD monitor. It was that easy...
Thanks for all the help guys
=D>

Dave H :D

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