Second Hand QL Display Issue

[PeterJ]

I'm vaguely looking at getting a QL over the next year (depending on price) so am doing some research, and this one seems to have what I think you call screen bleeding.

Is this likely to be the TV used, or anything more sinister?

Many thanks

[1024MAK]

That’s a very strange image.

If there was incorrect matching (electrical signal matching) then after a translation to a bright pixel or pixels, the horizontal line would tail off to the right for EVERY occurrence. Longer lengths of bright pixels creating a longer, brighter line to the right.

But that’s not what you see here.

If the custom chip (that produces the video in a QL, known as the ZX8301) was faulty, all the text would be unreadable. If the RAM was faulty, I doubt it would have got to the menu screen.

So i’m not sure what’s going on.

The QL can produce the following video outputs:

• UHF RF TV signal via a modulator.
• Composite video via the monitor DIN socket.
• Digital RGB via the monitor DIN socket.

With modern TVs, they expect the SCART function switching signals to be correct (unless the TV has a manual menu setting).
So a modern TV with an old SCART video cable can produce strange affects (often a black picture with strange ghostly vertical lines).

Do you know any more about the set up that was used?

Mark

[PeterJ]

Thanks for the information [mention]1024MAK[/mention],

This is the listing.

https://www.ebay.co.uk/itm/164347425443

Just looked again and some of the images look better than others.

[1024MAK]

It may be that the TV used, just does not light the intensity of the signal from the QL (the resistors used in the lead are too low a value, assuming it actually has any resistors).

One thing to note, that price is a bit steep for a basic QL even in working condition. I think I paid about £100 to £120. Of course prices may have gone up since then...

Mind, the box often adds £50...!

Mark

[1024MAK]

Yeah, just looked at completed listings on eBay and prices are definitely higher than four or five years ago...

Especially boxed and ‘working’ listings.

Mark

[PeterJ]

Thanks [mention]1024MAK[/mention].

I did have one some time back which I think I purchased for about £60, but then sold it (foolishly) when work was a little quiet.

Anyway, looking again and don't need a box, and will look at prices.

Cheers.

[bobs]

I’ll be selling mine in the near/mid future, but it’s boxed etc so perhaps not of use to you

[PeterJ]

Thanks [mention]bobs[/mention],

Let me know when you are selling it and the price.

Cheers