SCART cable for QL

[dilwyn]

I just noticed this on eBay, a company called RetroShack in Lancashire offering QL SCART cables for £9.95, free standard postage (£6.95 express) to UK, will supply overseas too.
http://www.ebay.co.uk/itm/Sinclair-QL-H ... rid=229508
While this allows you to connect a QL to a SCART TV or similar, many TVs and monitors will still lose a character or two on the edge of the screen, of course.

[robheaton]

I've used RetroShack for numerous cables over the years.
They provide top quality kit and their support is top notch too!

I have a couple of their QL Scart cables, they work well, I loose approx 3 characters in Monitor mode, but I don't think I loose any in TV mode.

[1024MAK]

I've used RetroShack for numerous cables over the years.
They provide top quality kit and their support is top notch too!

I have a couple of their QL Scart cables, they work well, I loose approx 3 characters in Monitor mode, but I don't think I loose any in TV mode.

I too have a SCART cable for my QL from retrocomputershack (along with various other SCART cables for other machines).
For those that don't know, it is the "video chip" in the QL that causes the "lost" 3 characters, as the QL sends the video information for these characters before the TV or monitor is ready to display them (in simple terms). This should only happen when the QL is in "monitor" mode. I get the same with my Sharp Aquos LCD TV. When the QL is in TV mode, it is fine

Mark

[robheaton]

Is there any way to restore the lost characters? A replacement video chip perhaps?

[Mr_Navigator]

Ok with my ever decreasing knowledge of electronics, can someone explain why this wouldn't work.

On Dilwyn's Documentation page there is a section on monitors designed specifically for the QL, the only one to have a circuit diagram is the "SINCLAIR VISION-QL MONITOR MANUAL"

Its in two halves, and two different levels of quality, tone and colour.

I've joined them together, corrected the colouring, tone and contrast as best as possible to get a reasonable full circuit diagram (enclosed is a lower resolution one, Dilwyn if you want the highest resolution image let me know but keep the two halves you currently have)

Assuming that:

• 1. The vacuum tube is a standard version vacuum tube and not some really special extra wide scan something type.
  
  2. The chip IC501 - HA11259 (I think, as I cannot read it clearly, enhanced or otherwise) can be obtained

ql-ic.png (75.78 KiB) Viewed 6546 times

Then the rest of the circuitry is made up of discrete components and could be replicated to some extent. Could not then instead of the HT circuitry be left out also the tube and the drivers for the guns, and the RGB signals that go to the tube circuitry be isolated and buffered in to the RGB of a SCART RGB.

I am assuming that somewhere in the circuitry the sync issue (3 character missing) has been taken care of.

Or am I just looking at this too simplistically?

It just seems so frustratingly feasible

I have done a search for the chip to see if a data sheet can be obtained for a better understanding, no luck so far.

So three questions for you QLer's out there (besides the first one at the beginning of this post)

• a. Does anyone have a circuit diagram of the Microvitec Cub QL RGB monitor?
  
  b. Does anyone still have a SINCLAIR VISION-QL MONITOR where they could look at the circuit and identify the actual chip number?
  
  c. Can anyone read or know the actual chip used in the SINCLAIR VISION-QL MONITOR or have the data sheet for it?

[XorA]

Is there any way to restore the lost characters? A replacement video chip perhaps?

If your one of the lucky ones a GBS8220 RGB->VGA converter can capture and convert the whole picture in monitor mode.

G

[1024MAK]

The problem is that the QL produces a non-standard video signal in monitor mode This is a timing problem. Not a processing problem. Messing with the RGB signals cannot change the timing of the information in these signals. Unless you capture and store the information (like the GBS8220 RGB->VGA converters do).

In theory, a lot of the older CRT based TVs and monitors that use discrete circuitry (not those which are made up of complex chips) could be adjusted or modified to display the full QL screen in monitor mode. This is called overscan, meaning that the guns in the CRT start producing each display line earlier than the spec says (and finish later).

Modern TVs however use complex chips (that need no adjustments, and so cannot be adjusted) that work to the correct specification.

Mark

[Mr_Navigator]

Many thanks Mark, that reply was very useful, I will now investigate the GBS8220 RGB->VGA system which on eBay is available from a variety of sources.

[Dave]

At the same time, you need to acquire a 5v DC supply capable of delivering 1A. This does not come with the board, but you will need it.

[RWAP]

There is the microvetic cub service manual - http://www.arcade-museum.com/manuals-mo ... splays.pdf - not sure if there are any differences to this one for the QL version...