The Sinclair QL Forum

Peter wrote: ↑Wed Mar 01, 2023 9:20 am

Derek_Stewart wrote: ↑Wed Mar 01, 2023 9:02 am I could only find CONC 16-001820E, here is the data sheet.

Sorry, I made a typo. I used the Conec 16-001810E, now corrected in the original post.
The 16-001820E is obviously wrong width, probably not a good idea to post the datasheet here. Hope people are not confused now.

Sorry, data sheet removed

For those who like an easy to solder version, but not fitting a D-Sub hood, I designed a larger PCB, sized 50 x 30.8 mm: +5V power can be supplied by UBS-C at the side, a Q68-style 2.1mm coaxial connector at the rear (center is +) or from a modded QL.
The QL is protected by a diode from feeding back +5V into the machine, if it is not modded.
A cable clip can be provided, I had to add a little glue to fix it properly.
Please find Gerbers (for Aisler), schematics and placeplan attached. Have fun.

Side note: The holes for the module pins are nominally 0.8 mm. On my prototype PCBs, this was closely sufficient for modules with pre-soldered pins.
If other PCB manufacturers are used, especially cheaper ones with high tolerances, pins should be selected with care.

Hi all,

during the build of a second QL-VGA converter I found a strange issue. After copying the code to the virtual USB drive the board worked as expected. But after de-powering and re-powering it seems the code has been vanished or the RP2040 failed to start. In fact another forum member reported the same issue.
Quick research and I found that some RP2040 failed to start due to unstable oscillator during startup. Solution is to set
to 64

Oliver was very helpful and he modified the code withing minutes. Thanks a lot!!
At least at my side this solved the problem.

Find attached the updated code here.

This code is for the RP2040 zero as described earlier in this thread by Peter

Another PCB/Case option I whipped up that uses the full size Pico, https://github.com/djtersteegc/video_if ... doc/pcb.md

Thanks for sharing. How did you shield the precrimped cable?

Peter wrote: ↑Wed Mar 08, 2023 8:06 am Thanks for sharing. How did you shield the precrimped cable?

I didn't. They are short enough it didn't seem to matter.

Hi,

Looks very neat, I would make the case black.

I have ordered some PCBs for the RP2040-Zero, just waiting for delivery.

But I like the design of the full size RP2040 version. Maybe I will make some as well.

Hi,
I've just finished my QL pico VGA using a strip board (it didn't look so difficult) I guess I have some Sync problems. Image is not steady with some horizontal jumps and the rainy band moves from top to botom, then the "signal?" Screen apears briefly.
If I attach a tv to the composite output the image gets steadier but the moving band worsens notably.. What should I check first ? Connections seems tonbe good..
Thanks

You didn't even write which module you used.
Are you aware that different binaries are needed for the (small) RP2040-Zero and the (larger) Raspberry?
Did you keep the wires to the QL either very short or shielded?
Did you check that the QL RGB output (not composite) is working correctly, e.g. with a different converter?

Peter wrote: ↑Fri Mar 17, 2023 9:16 pm You didn't even write which module you used.

I'm sorry about that... I used the conventional raspberry Pi Pico, the larger one, and downloaded the firmware from the github page

Peter wrote: ↑Fri Mar 17, 2023 9:16 pm Are you aware that different binaries are needed for the (small) RP2040-Zero and the (larger) Raspberry?
Did you keep the wires to the QL either very short or shielded?

Wires from QL are not shieded but about 7cm long, I guess they are short enough.

Peter wrote: ↑Fri Mar 17, 2023 9:16 pm Did you check that the QL RGB output (not composite) is working correctly, e.g. with a different converter?

Yes actually I am using a NEC Multisync II monitor connected directly to the same (short) adapter from the QL's DIN to a db9 Cable.. and image is just great.

I guess you are suggesting me to look for interferences, maybe the QL itself be the source ? I'll try to shield the short wire and the adapter itself somehow and check again.
I am a bit concerned about the fact that having the co posite connected at the same time changes it behavior.. composite image is not very good I think some capacitors may need some care on the machine..
Thanks for your help and forgive my clumsiness in previous post.