Will changing VC1 fix my colour problem?

[necronom]

I've added a link to S39 so I can get colour composite for recording video while using RGB for the main display. I did a quick test yesterday with a paperclip and I was getting a flickering colour/black and white image (bad connection I thought), but now I've connected it properly I'm not getting colour. I did briefly get a flickery image, but it's back to black and white again.

I've done some research, and it sounds like twiddling VC1 may help. I don't want to mess up my RGB, though I think that may be a totally isolated signal and not affected by VC1, though I would like to check first.

Is it safe for me to twiddle the pot while switched on without any worries about making things worse?

[arg]

Yes, VC1 only affects the composite output, has no effect at all on RGB.

It's quite likely to be the cause of intermittent colour/monochrome.

[necronom]

Thanks.
It didn't work. I got an occasional flicker, but nothing useful.
Unless there's a faulty chip or something, I may have to do the RF Composite mod if that's got a chance of being any better.

[necronom]

I think I'll just forget about that idea and get a Scart splitter. It's £50, but will split the RGB for me. That should work well.

[maniacminer]

I think I'll just forget about that idea and get a Scart splitter. It's £50, but will split the RGB for me. That should work well.

I assume you mean £5? Do you have a device for recording that takes an RGB signal directly? To get colour, you will need to add some extra capacitance in location C51 like 10pF or more if there is a capacitor already fitted at this location.

[necronom]

No, £50 (including postage).

All the others are male in to 2 x female out. I have one of those.

I got a gender changer, but that doesn't swap the in/out pins. The only way into it was to destroy the case so I didn't bother. I tried swapping the pins on one of the the Scart cables but ended up getting the BBC B going to the tv, then BBC 1 going to my capture card!

I ordered a proper active buffer professional one to stop me having problems and give a good picture. I can also use it with my other computers, as they mostly have Scart outputs.

I thought about changing the capacitor, but with the amount of problems I'm having with it at the moment I just want a quick and easy fix that I know will work.

[1024MAK]

Ideally for a SCART splitter, you want an active device that electronically amplifies/buffers the signals so that the signal amplitude is not effected.

That means that it has to have a power source.

VC1 only affects the colour component of the compositive video output and the TV/RF/UHF output. Even when VC1 is not adjusted correctly, you should still get a monochrome video a signal.

Mark

[necronom]

Yes it's a proper active one with power.

I do get a monochrome signal. I didn't know how much to turn it. It seems to keep going, but I didn't know if it actually unscrews, or if there is only 360 degrees of positions.

Hopefully the splitter will arrive today and I can try that.

I got an Oscilloscope yesterday, so I might be able to work out what's wrong if I needed to, though I'm a total beginner with it.

[1024MAK]

VC1 is a capacitor trimmer, there are no end stops but rotating it further than one turn (360 degrees) just gets you back to where you were.

Most have a metal vane that are half of a circle and it's the position of this that is moved as you rotate the adjustment screw.

Mark