QL-VGA v2

[Popopo]

Nice thank you, could you address me to this place where you have them? to check the price out.

https://www.sellmyretro.com/offer/details/60557

Ou! thank you, I was looking for it and didn't find it.

[mk79]

I asked it because I have some projects and usually it takes me a lot of time to solder SMD components and ICs, I tried to use the assambly service of JLCB but... I couldn't get it due to BOOM components and then some issues with the positions of the components or references from the Gerbers. Now I can get an idea to try it again.

Yes, I started to even let them solder low-component count boards in some cases because soldering has lost its appeal after doing it so much for QL-SD and stuff... also, debugging any wrong solder joint is no fun either. For the upcoming QL-SD batch one board was especially stubborn and took me an hour to get it working. Which is the main problem with JLCPCB, they just don't have a large enough selection of (available) chips.

I use KiCad and the JLCKicadTools script to create the assembly files. It's on GitHub somewhere. You still have to check all parts are rotated correctly and have the right size. The engineer from the company I used for QL-VGA production noticed one wrong sized capacitor for example, so the additional money does help I noticed it was missing on the JLCPCB boards, I just didn't make the connection that it fell off the board during soldering as it was too small for the pads!

Cheers, Marcel

[mk79]

Nice thank you, could you address me to this place where you have them? to check the price out.

https://www.sellmyretro.com/offer/details/60557

Ou! thank you, I was looking for it and didn't find it.

The search doesn't show any results that are currently not available, which is a problem I think. I have to use google to search for it on SellMyRetro.

[afx]

For the upcoming QL-SD batch one board was ...

That's good news!!

Can you give us more details about that new batch? Is it the QL-SD external rom port version?

[varmfskii]

Yeah, I guess the QL-VGA "screen-saver" is displayed well when the QL is switched off, this is not a monitor issue.

Amazingly little details are known about how exactly NTSC QLs really work, and I don't have one either, so QL-VGA probably cannot handle them as-is. But when you switch to a "normal" ROM, be it MG, JS or Minerva (my suggestion), it should revert to the standard 50Hz behaviour and QL-VGA should work fine with it. This has other advantages, too, because frankly no QL program cares about 60 Hz, they all assume 50 Hz as 60 Hz is just too uncommon.

If you want to try something first, issue "POKE 98403,0" in Basic and check if the picture improves. Hope you get your QL to work again first, of course. By the way, NEVER hot-plug any display to the QL, not QL-VGA and not any RGB monitor. Chances of frying the ZX8301 are high.

It was connected, working with its issues. I went off for several hours. When I came back, no pictures at all. Shut down everything, connected to QL to SCART cable and SCART to HDMI powered back up and no response from the hardware.

I presume it was the weather (the only other is the QL-VGA frying something while just connected, which I don't believe is what happened).

[mk79]

Can you give us more details about that new batch? Is it the QL-SD external rom port version?

I opened a new thread with some details.

[varmfskii]

Well, good news and bad news on my QL-VGA (v2) issues. I got a new ZX8301 and a ROM switcher. So, my QL works again. Yay!! Unfortunaely Using either Minerva or the JS (instead of the JSU) ROM. I have the same timing issue corrupting the display. Obviously there is something odd about the timing on my QL that interferes with the operation of the QL-VGA. Any other Ideas are welcome.

[mk79]

Well, good news and bad news on my QL-VGA (v2) issues. I got a new ZX8301 and a ROM switcher. So, my QL works again. Yay!! Unfortunaely Using either Minerva or the JS (instead of the JSU) ROM. I have the same timing issue corrupting the display. Obviously there is something odd about the timing on my QL that interferes with the operation of the QL-VGA. Any other Ideas are welcome.

Is the picture static or does it change over time?

[varmfskii]

The distorted sections of the screen (at least at their edges) shimmer between adjacent pixel values. It is very much like the pixels go in and out of sync a few times for every scan line.

[mk79]

I'm still not sure what to make of it. QL-VGA v2 can handle pixel clocks from 9.976 to 10.024 MHz, so even if the crystal is way off it should cope. But then in your example picture we see that the lines are complete, which I think means that the correct clock is detected. It looks more like a frequency jitter within the line that I've never seen before this way. Does your QL also have the 74HC daughter board modification as seen in the picture here?


All the best, Marcel