Display (on LCD TV) problems

[oxmikeinmi]

Hi - I'm new here - I've just got a CPC 464 (no monitor) to add to my 8-bit collection. A £7 bargain off ebay in absolute A1 condition, complete w/ box, manual and game tapes!


I'm located in the US (originally from UK) - my collection includes a ZX Spectrum (rubber key), Spectrum +, Acorn Electron, Oric Atmos (my first computer bought back in '84), Commodore 64 and now a CPC464.


My set-up consists of two TV's. The first is a multi-region (PAL/NTSC) CRT Sony Trinitron w/o SCART. This is connected to the Spectrum (RF), Spectrum + (composite) and Commodore 64 (composite).


The second TV is a non-brand (NTSC) LCD. I connect the Oric and the Electron to this via SCART (from retrocomputershack) using this device which converts PAL to NTSC and SCART to HDMI. Both these machines have rock solid crystal clear displays (w/o any modifications).


Now to my problem ... I bought a new SCART lead (from retrocomputershack) and connected the CPC to the LCD via the same device and after initially getting a blank screen w/ OSD flashing every few seconds I now get the output shown below:






To get this I modified the SCART connector by adding a 100uF capacitor between pins 16 & 18 per the instructions on this site.


Is there a fix to solve this shadowing/ghosting of an otherwise perfect display or is this simply a consequence of having an incompatible TV?


The CPC works perfectly well with the CRT TV using a RGB to composite converter.


Any suggestions or advice to rectify this issue would be most appreciated.


For what it's worth I also get the same output from the CPC on a Sony Bravia LCD tv.


Thanks in advance


(sorry if this is a repetitive question - I did look through the forum before posting but only found one reference to this problem w/o any solution).


Mike

[MacDeath]

Nice dual field here... cool demo effect I guess... oh wait...


I guess someone like Bryce may have a real answer.


Have you tried on different monitors ?
Is this a 16/10 ratio monitor ? tried to modify the settings on the "TV" ?


Like turn the picture ratio into 4/3... check the refresh or whatever .


Anyway, it is always better to use a real CRT monitor because those machines were especially designed for those.
But yeah, it is far from practical these days.

[Sykobee (Briggsy)]

Looks like a 2 scanline + 4 character echo (around 135ns) on the green signal.


If you do INK 0,0 does the shadow text go green?

[TotO]

So cool ! 

[MacDeath]

Looks like a 2 scanline + 4 character echo (around 135ns) on the green signal.

I guess you also miss one pixel...

The Blue seems ok, but it looks like the yellow is the pastel one, and the "second display) seems pastel cyan or some sort of pastelgreen/ocean green...


Perhaps one of you cable/solder may "leak" ?


Otherwise it seem the yellow characters are masked...really looks like a proper dual playfield in 1bpp + 1bpp (2 inks + 1 ink masked).


Is this even possible to dual playfield iin Mode1 ?

[ralferoo]

using this device which converts PAL to NTSC and SCART to HDMI

That device must be buggy. There's no way the Amstrad can be causing that delay itself, it has to be the device.

It's quite possible it's because the Amstrad outputs colour during the front porch section of the video which isn't quite to video spec as it's supposed to be black during the front porch. You can try doing "border 0" to see if the problem goes away. Even if it does, though, there's no real solution to it other than by using something like Bryce's s-video converter.

[oxmikeinmi]

Thanks for the replies.

I re-soldered the SCART lead tonight but with no luck - I still get the same issue.

The text on the screen is actually bright yellow - the photo I posted doesn't show this very well as it was taken with my phone camera - and the shadow/ghost text is a light blue/grey colour.

Changing the colour of the background or text has no real effect - although some colours reduce the intensity of the shadow/ghost text slightly.

Yes, I did try this on a few different LCD tv's but all produced the same output. The only TV that works is an old CRT (Sony Trinitron) which I am able to connect to with a RGB to composite converter (This tv does not have any SCART inputs).

I guess for now I will live with the CRT and just enjoy my new computer.

Thanks again!

[TheCorfiot]

 This is a scart issue I have come accros before and affects lcd tv's more than crt..

Basically, you need to connect the sync (not mono output, that's what the ghosting is) to pin 20 of the scart
And apply a separate +3v fast blank switching voltage to pin 16...you can use a dc jack inline system as your oric cable has as that also does not have a +5v output on its rgb socket...
If you do break into the +5v supply to send the voltage to the scart ensure you fit a series 270 ohm resistor to drop it to 3v.

I can promise you that will solve your problem...

[TFM]

I'm located in the US (originally from UK)

Hi, can't help you with the monitor - sorry. But if you ever stop by at New Orleans, let me know ,-)

[ukmarkh]

If it helps... maybe we should start listing the LCD's that do work?


My 15" Goodmans LCD LD1501 works great on the stock CPC and the PLUS range, with the scart lead I purchased off ebay 

[redbox]

If it helps... maybe we should start listing the LCD's that do work?

My Technika LCD19-220 works well with a classic CPC.

Now and then I get a very slight shift of the picture (about 1 screen char) to the left and back though.  Any ideas why?

[Devilmarkus]

Now and then I get a very slight shift of the picture (about 1 screen char) to the left and back though.  Any ideas why?

Is it, when you connect a CPC Plus?



Edit: To oxmikeinmi:
Did you accidentially connect the luminance signal, too, somewhere? (e.g. to FBAS?) If so, disconnect it...

You only need R,G,B, Sync and Ground.

[redbox]

Is it, when you connect a CPC Plus?

Nope, normal CPC 6128.

[ralferoo]

Did you accidentially connect the luminance signal, too, somewhere? (e.g. to FBAS?) If so, disconnect it...

As he's from the US, he'd know FBAS better as CVBS (i.e. the yellow plug RCA)....

[TFM]

As he's from the US, he'd know FBAS better as CVBS (i.e. the yellow plug RCA)....

Naah. He is originally from a civilized country.

[MacDeath]

Guys, would be great to actually put all those datas on "working configs" at some page like "LCD screens and CRT emulation" at CPCwiki...

[oxmikeinmi]

Ok we have a winner!

This is a scart issue I have come accros before and affects lcd tv's more than crt..

Basically, you need to connect the sync (not mono output, that's what the ghosting is) to pin 20 of the scart
And apply a separate +3v fast blank switching voltage to pin 16...you can use a dc jack inline system as your oric cable has as that also does not have a +5v output on its rgb socket...
If you do break into the +5v supply to send the voltage to the scart ensure you fit a series 270 ohm resistor to drop it to 3v.

I can promise you that will solve your problem...

I didn't follow this solution exactly but it did lean me towards modifying the SCART connection - basically the lead I bought was wired per the "alternative RGB wiring" found on this site. I added the capacitor between pins 16 & 18 to stop the OSD keep flashing up on the screen.

After reading the suggestion above I moved the SYNC from pin 16 to pin 20  (removing the LUM in the process - so effectively doing as Devilmarkus advised too) and added a 9V battery to connect between pin 8 and pin 18 per this solution leaving the capacitor between pins 16 & 18 - it's not very pretty but it resolved the issue.



The screen now appears like this ....



The text is nice and clear and bright yellow (again not really showing in the poor quality photo) with no shadowing/ghosting to be seen anywhere!

My next move will be to remove the 9V battery and tap in to the 5V power supply per the suggestion above - I intend to follow this example which from my first read follows the same solution.

Thanks guys for the excellent feedback.

[TheCorfiot]

Told ya...

Well done buddy..

[Gryzor]

Oh, nice work mate! But please do switch it to a 4:3 ratio


...and welcome!

[oxmikeinmi]

Thanks

The CPC now sits proudly in what my kids call "Dad's retro battle station".

[Bryce]

Very nice collection.

Bryce.

[Sykobee (Briggsy)]

I've always liked the look of the red and black keys on the Oric Atmos.


Nice setup indeed.

[Gryzor]

I'd say the Oric and the CPC totally own the room!


Lovely space, btw

[The Last Bandit]

Oh, nice work mate! But please do switch it to a 4:3 ratio


...and welcome!

Apply 12V to SCART pin 8 will select AV channel with 4:3 aspect ratio. A few scanlines wouldn't go amiss either