The strange case of the Commodore 64 colour bands.

[stephen_usher]

The S-Video cable arrived today and... Neither my display nor any of the converters I have support S-Video. There's enough of the chroma feeding back into the luma (as on the PAL modulator they share one transistor output, a cost cutting design) for the TV and my cheap SCRAT-> HDMI convertor to pick up the colour information.

Oh well. I'll have to wait until the capacitors arrive before I can get any further. As they're unlikely to arrive before the end of the working week I won't actually have them until after my Easter break.

[stephen_usher]

I managed to find my composite/s-video USB capture device in the loft and connected it up.

The interesting thing is it would only (just about) sync if I used PAL_60. My C64 is most definitely not a 60Hz machine. Even then it was jittery, with the screen display having jitter interleaved lines and wobbling a bit. (Not quite the same as @rubber_jonnie's Atari XL.) This wobbling phased in and out... Like a timing problem from the crystal/capacitor with overtones.

Here's a still capture from Sarah-Jane Avery's "Briley Witch Chronicals" showing the banding and a little bit of the jitter on the left:

Screenshot_2022-04-05_19-15-43.png (557.96 KiB) Viewed 1708 times

And here's the desktop.

Screenshot_2022-04-05_19-16-14.png (336.58 KiB) Viewed 1708 times

Unfortunately I can't separate the luma and chroma.

[rubber_jonnie]

That banding is really very noticeable, hope you get the caps soon so you can see if it makes a difference.

Don't you just hate weird video problems!!

[mrbombermillzy]

I don't have any answers for you @stephen_usher but (IIRC) the C128 suffered from the colour bars problem.

Never noticed anything this bad on the ones I owned, but it was (still is?) a thing for many people apparently.

I trust you will get to the bottom of it in the end

[stephen_usher]

That banding is really very noticeable, hope you get the caps soon so you can see if it makes a difference.

Don't you just hate weird video problems!!

Yeah.

Well, it the replacement cap for the clock circuit doesn't work I can try a LumaFix64 as a last resort.

[stephen_usher]

I don't have any answers for you @stephen_usher but (IIRC) the C128 suffered from the colour bars problem.

Never noticed anything this bad on the ones I owned, but it was (still is?) a thing for many people apparently.

I trust you will get to the bottom of it in the end

Yeah. From what I've read and seen on videos the early C64s weren't supposed to have as bad jail bars as the later C64C.

Having said that, the clock circuit capacitor is REALLY out of spec at 17pF. 10pF +-5% would be in the range of 9.5pF-10.5pF. We'll just have to see if replacing it makes any difference.

[rubber_jonnie]

I don't have any answers for you @stephen_usher but (IIRC) the C128 suffered from the colour bars problem.

Never noticed anything this bad on the ones I owned, but it was (still is?) a thing for many people apparently.

I trust you will get to the bottom of it in the end

Yeah. From what I've read and seen on videos the early C64s weren't supposed to have as bad jail bars as the later C64C.

Having said that, the clock circuit capacitor is REALLY out of spec at 17pF. 10pF +-5% would be in the range of 9.5pF-10.5pF. We'll just have to see if replacing it makes any difference.

Will keep my fingers crossed!!

[rubber_jonnie]

I dont have any answers for you @stephen_usher but (IIRC) the C128 suffered from the colour bars problem.

Never noticed anything this bad on the ones I owned, but it was (still is?) a thing for many people apparently.

I trust you will get to the bottom of it in the end

Yeah. From what I've read and seen on videos the early C64s weren't supposed to have as bad jail bars as the later C64C.

Having said that, the clock circuit capacitor is REALLY out of spec at 17pF. 10pF +-5% would be in the range of 9.5pF-10.5pF. We'll just have to see if replacing it makes any difference.

I'll try and check my C64C, see if it has bad jailbars, though I haven't noticed anything thus far.

[stephen_usher]

Well the "Plan B" items have arrived, the heat sinks and LumaFix64.

I'd still prefer to replace the capacitor first, but they're still stuck in courier hell. RS Component's "next day delivery" for these items involved a 3 day wait before dispatch and then it's got to get through British customs etc.

[rubber_jonnie]

Well the "Plan B" items have arrived, the heat sinks and LumaFix64.

I'd still prefer to replace the capacitor first, but they're still stuck in courier hell. RS Component's "next day delivery" for these items involved a 3 day wait before dispatch and then it's got to get through British customs etc.

When do you think you'll get a chance to fit the LumaFix? Be good to see you get this one resolved.