ZX Spectrum +2 Grey video artifacts

repetto74
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ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Tue May 02, 2017 7:02 pm

Hi Guys,

I just got a Spectrum 128k +2 from ebay. It came with its power supply and the scart video cable. The machine is working pretty good but when hooking it up to the TV I just get a lot of video artifacts as per this small video. What this can be?? :?: :?:

https://youtu.be/iTwKrU1oOPI

RWAP
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Re: ZX Spectrum +2 Grey video artifacts

Post by RWAP » Tue May 02, 2017 7:54 pm

It is possible that it has the wrong SCART cable. As far as I recall, the Spectrum +2 (grey) uses a different one from the Spectrum+128 and the black Spectrum+2A / +2B and +3 - see http://www.fruitcake.plus.com/Sinclair/ ... TCable.htm

repetto74
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Re: ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Tue May 02, 2017 8:05 pm

Hi Rwap,

This is the scart cable. It looks like being the original provided with the Spectrum if it was the case at the time the Spectrum +2 was sold. Note that the labeling on the different ports is in french on the Spectrum case.
Attachments
IMG_5967.JPG
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Re: ZX Spectrum +2 Grey video artifacts

Post by RWAP » Tue May 02, 2017 10:35 pm

You can't tell by looking at the outside of the SCART cable - you need to check the wiring and resistor values as per that website. Unfortunately, I don't know enough about SCART leads to help.

The Spectrum was not supplied with a SCART lead - it would have been sold with a simple TV RF lead - so someone has produced this SCART lead afterwards - it could be home made, or purchased - but who knows what wiring diagram they used to make it?

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Paul
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Re: ZX Spectrum +2 Grey video artifacts

Post by Paul » Wed May 03, 2017 4:26 am

Sorry Rich, as far as I know French Spectrum were sold with SCART lead and without modulator (because of their weird Color system).
So if it's a French spectrum without modulator then the Scart should be fine.
Does this Spectrum still have its original capacitors?
If so, don't use it and replace all electrolytic capacitors first (or have someone do this for you).
Kind regards Paul
In theory, there is no difference between theory and practice. But, in practice, there is.

repetto74
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Re: ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Wed May 03, 2017 7:45 am

Hi Paul,

No clue of what has been done in the past. I still did not get my hands on the motherboard. I will open it and have a look at the capacitors. I have noticed that patterns may change sometimes to a very grey interference. It could be a bad solder joint on the video DIN socket.

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1024MAK
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Re: ZX Spectrum +2 Grey video artifacts

Post by 1024MAK » Wed May 03, 2017 7:50 am

One thing to be aware of: When Sinclair (Amstrad) were selling the +2 grey, most TVs had manual SCART switching. Now most TVs only have automatic function switching.

The UK version of the +2 grey does not provide the correct voltage and current levels on it's RGB/video out socket for the function switching. But I don't know if the French version does output the correct voltages. Also unknown is the wiring of the SCART lead you have.

So if you could open the two connectors up and tell us what wiring (if any) connects to pin 8 and pin 16 in the SCART plug, that would be useful. And if these pins do have connections, the colour of the wires, so at the DIN plug end we can see which DIN plug pin they go to. Or take photos from various angles that are good enough that we can see...

Mark

repetto74
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Re: ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Wed May 03, 2017 10:44 am

Hi Mark

First of all thank a lot for your interest on this matter. I will do as you asked and open up the scart box and din lead to see how the wiring was done. I will report back 😊

repetto74
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Re: ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Wed May 03, 2017 5:31 pm

Ok so I have the pinout for this scart cable : :D

DIN LEAD -------------- SCART PIN

Pin 7 --> green wire --> pin 11
Pin 3 --> black wire --> pin 13
Pin 5 --> brown wire --> pin 20
Pin 2 --> grey wire --> pin 8
Pin 8 --> blu wire --> pin 7
Pin 4 --> yellow wire -->pin 16
Pin 1 --> white/purple wires --> pin 2
Pin 6 --> red wire --> pin 15

There is a purple wire bridge on the scart between pins 2 and 6 (2 is shared with the white wire). There is also a purple wire bridge between pins 18 and 13 (13 is shared with the black wire).
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repetto74
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Re: ZX Spectrum +2 Grey video artifacts

Post by repetto74 » Thu May 04, 2017 5:20 pm

Here is another video showing the nasty interferences on a white background.

https://youtu.be/r8XWVmRnM9Y

:?

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