Sinclair QL Composite Video Out

[RWAP]

I have received an order from Brazil for a QL - now the standard TV out is no good to them, and they can't use a SCART connector...

So the option was to perform the simple composite video mod, as used widely on the ZX Spectrum - see http://womblesretrorepairshack.blogspot ... o-mod.html

For some reason, although the picture is stable, the colour is too green now - a white screen appears slightly mint in colour...

I have changed the MC1377P display controller, but without any effect (and even redone my soldering / used a different wire in case).

The RGB picture on a QL monitor is fine - I am sure it was fine when connecting to a TV using UHF PAL before...

The QL is an issue 5 board.

Any ideas what the problem could be?

Such a shame that only mono composite video is available on the RGB socket!

[tofro]

Rich,
if composite is on the greeenish side that typically means your overall signal level of the composite signal is too low.
I would check for bad solder joints, or you could try and pick the composite signal directly from pin 9 of the MC1377.

Cheers,
tofro

[RWAP]

Rich,
if composite is on the greeenish side that typically means your overall signal level of the composite signal is too low.
I would check for bad solder joints, or you could try and pick the composite signal directly from pin 9 of the MC1377.

Cheers,
tofro

OK thanks - that is worth a try - which is pin 9 ??

[tofro]

OK thanks - that is worth a try - which is pin 9 ??

When viewed from the top, start at the notch, count counterclockwise. Datasheet is here:
http://www.datasheetcatalog.org/datashe ... 1377DW.pdf
Figure 15 is interesting: It says, Composite out should have a 75Ohms resistor in series - Which I can't find in the QL schematics.....
When checking that, you would probably want to bend pin 9 up so it's not inflicted by the rest of the QL circuitry

[flyer.gio]

Hi Rich,
you can get the PAL composite video from the pin 1 of the RGB connector and the monochrome video from the pin 3 (or maybe the opposite, I don't remember well) as you can see in the schematics diagram or as reported in the service manual.
You don't need to perform any mod.
I have an issue 5 Italian QL and I normally use the PAL (color) video signal from that connector.

Ciao, Gianni

[RWAP]

Hi Rich,
you can get the PAL composite video from the pin 1 of the RGB connector and the monochrome video from the pin 3 (or maybe the opposite, I don't remember well) as you can see in the schematics diagram or as reported in the service manual.
You don't need to perform any mod.
I have an issue 5 Italian QL and I normally use the PAL (color) video signal from that connector.

Ciao, Gianni

Ah - yes pin 1 for the PAL composite video, and pin 2 for the Ground - see
http://www.fruitcake.plus.com/Sinclair/ ... ableQL.htm

I have adapted a lead made for a mono QL monitor and it works (although still not brilliant white!)

[Marq]

The composite out seems to be just bad, even on a perfectly working QL. I got a lot better composite/s-video output using a somewhat affordable http://www.js-technology.com/store/prod ... product=17 SCART to s-video converter together with a cheap passive composite converter.

[dilwyn]

Ah - yes pin 1 for the PAL composite video, and pin 2 for the Ground - see
http://www.fruitcake.plus.com/Sinclair/ ... ableQL.htm

I have adapted a lead made for a mono QL monitor and it works (although still not brilliant white!)

That same site http://www.fruitcake.plus.com/Sinclair/ ... ulator.htm lists an interesting device, a 128k flash memory device for Spectrum which emulates a ZX microdrive cartridge.

Now that Adrian Ives is working on bringing Peter Graf's SD card interface for QL to market, assuming the prototype design is kept, it means one option is to mount it in the mdv2_ position (remove mdv2, add the SD card interface). It'll be interesting to see QL users able to plug an SD card into an original QL microdrive slot.

And as an aside, it's always been possible to use ZX Spectrum microdrives with the QL, but because you need a mdv cable long enough to twist and the microdrive faces backwards away from the user. Also, I seem to remember they wouldn't format a QL mdv cartridge reliably, but would read and write. Memories!

Dilwyn

[Jungsi]

I've tried to connect the TV with the composite signal from pin 1 and 7 for colour - the screen leaves black. When I use pin 3 and 7 for black and white I got a fine picture. Do you have an idea why I only get with black and white a picture on the screen?

[dex]

Shouldn't be 2 (GND) instead of 7 (RED)?