Author Topic: Is there differences between CPC and CPC+ video output???  (Read 2768 times)

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Offline SyX

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Hi guys! :)

I have attached my CPCs to the only TV in the house (Samsung 4900), using this Scart2HDMI converter.

The cable that i am using with the 6128+ is the one of Retro Computer Shack and for the 6128, i am using the old one that i made a few years ago for my CRT TV. Both cables are RGB and use the same schematic and the only difference that i can see is the cpc+ one have a resistor in each RGB pin.

Well, now the funny thing, the 6128 looks AMAZING, FULL HD 50Hz, vibrant colours and although i have not tested a game using scroll, the scroll fxs in the Batman demo are supersmooth (i was really surprised by this).

* fotocpc.jpg
(41.26 kB, 624x369 - viewed 195 times)

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And now the X Files moment, the CPC+ only shows video for like half second and then goes black, i can hear the music coming from the TV, but no picture at all

I don't know what i could do for fixing this. Somebody has got an idea why is this happening? And how could i fix this?

It's a shame that one of the few CPC+ in Brazil is not ready for public display, because i would love to bring it with me to the faculty for one of the videogames conferences that i am giving.

Offline CraigsBar

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Re: Is there differences between CPC and CPC+ video output???
« Reply #1 on: 20:54, 04 December 15 »
In my experience the plus machines are far more fussy with their scart output than either the cpc's or the gx4000. I guess this is also shown here.
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Offline ||C|-|E||

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Re: Is there differences between CPC and CPC+ video output???
« Reply #2 on: 20:54, 04 December 15 »
Oh! sorry, I misunderstood...  :picard:

Offline SyX

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Re: Is there differences between CPC and CPC+ video output???
« Reply #3 on: 20:48, 07 December 15 »
anybody?

Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #4 on: 20:53, 07 December 15 »
The Plus does't seem to kick out the right voltage for the RGB select pin to work. So cut the RGB select wire inside the SCART and place a 1.5v AA battery in line (preferably with a switch) and it will work like a charm. Battery negative, to the ground pin in the start, positive to the RGB select pin.
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Offline arnoldemu

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Offline SyX

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Re: Is there differences between CPC and CPC+ video output???
« Reply #6 on: 01:02, 08 December 15 »
Thank you very much, @chinnyhill10 and @arnoldemu (i am going to need a few days to read all the post from the last year and a half), i will try tomorrow and i hope to have good news too.

Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #7 on: 01:37, 08 December 15 »
Thank you very much, @chinnyhill10 and @arnoldemu (i am going to need a few days to read all the post from the last year and a half), i will try tomorrow and i hope to have good news too.


You don't need to read all the posts from the past year and a half. Your first stop is to try the battery solution as its quick and easy.
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Offline dragon

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Re: Is there differences between CPC and CPC+ video output???
« Reply #8 on: 14:44, 08 December 15 »
Really searching today a tv  with cpc in mind(and general tv) is a pain in the ass.

Samsung have removed the scart in smartv series, sony well.. they suffer from "poltergeist mode"  the control remote  of the bravia works with all bravias,  i return my new bravia to the shop because it changue my 2 Bravias at the same time lol.

Lg appear haver very bad contrast and very high input lag....

Now i  read this and the converter scart hdmi maybe not work with the plus  :-\ Lol.




Offline Bryce

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Re: Is there differences between CPC and CPC+ video output???
« Reply #9 on: 15:07, 08 December 15 »
My recommendation is to try and find a TV with an S-Video input. These tend to give good, reproducable results and converting the CPCs RGB to S-Video requires just a simple (and tiny) device. The S-Video cabling and connector are also smaller and more reliable than SCART.

Bryce. 

Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #10 on: 16:53, 08 December 15 »
My recommendation is to try and find a TV with an S-Video input. These tend to give good, reproducable results and converting the CPCs RGB to S-Video requires just a simple (and tiny) device. The S-Video cabling and connector are also smaller and more reliable than SCART.

Bryce.


Disagree. S-Video is now even more obsolete than SCART in Europe and requires further signal processing step that degrades the signal. Many TV's now lack any S-Video support but RGB support is still fairly widespread (although sadly some manufacturers have dropped SCART and have put the RGB on propitiatory connectors). The CPC is native RGB and it makes far more sense to keep the signal native than to convert.


The 1.5v battery hack is so easy even I managed to achieve it. The only gotcha is that if you plan to leave the SCART plugged in for any length of time you must install a switch or the battery will go flat.


The battery hack is easy to test and can be made up in 15 minutes. If it works you can then do the job properly. You might even try to source the voltage from the CPC or its PSU (although I preferred battery as the lower voltage still worked and it seems safer).
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Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #11 on: 16:56, 08 December 15 »
Really searching today a tv  with cpc in mind(and general tv) is a pain in the ass.

Samsung have removed the scart in smartv series,


Really? The ones last Summer still had full SCART but I had heard some models still had SCART but only via a special adaptor Samsung sell.. Eg this - Samsung UE40C7000 LED TV Scart Socket Adapter Cable: Amazon.co.uk: Electronics


So Samsung save 50 pence during manufacture and then gouge users for far more after purchase.
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Offline Bryce

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Re: Is there differences between CPC and CPC+ video output???
« Reply #12 on: 17:05, 08 December 15 »
Actually the battery hack isn't really needed, a capacitor with the correct wiring will work 99% of the time and you don't need to remember to turn it off.

I agree that RGB will give a slightly better picture, but the problem is that most TVs now use a processor to sample the RGB sync signal at the exact frequency and any variance from this means that the picture flickers or in some case doesn't display any sensible picture at all. S-Video doesn't suffer from these problems. Unfortunately, many retro computers varied from that frequency by quite a bit, or produce a sync signal of the wrong level, which also causes problems. Yes, the S-Video picture is slightly less sharp than straight RGB, but the chances of it working on multiple TVs / Computers is much higher.

As far as TVs with S-Video inputs is concerned, it seems to be a manufacturer preference. Some manufacturers include it on all TVs whereas some have removed it completely. You just need to know which manufacturer to go for. Unfortunately this won't go on for ever, so we should really be looking at cheap reliable Y,Cb,Cr/Y,Pb,Pr or HDMI solutions.

Bryce.

Edit: I doubt Samsung removed SCART to save 50 cents, more likely that it allowed them to make the TV a few millimetres thinner.
 
« Last Edit: 17:07, 08 December 15 by Bryce »

Offline dragon

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Re: Is there differences between CPC and CPC+ video output???
« Reply #13 on: 17:24, 08 December 15 »

Really? The ones last Summer still had full SCART but I had heard some models still had SCART but only via a special adaptor Samsung sell.. Eg this - Samsung UE40C7000 LED TV Scart Socket Adapter Cable: Amazon.co.uk: Electronics


So Samsung save 50 pence during manufacture and then gouge users for far more after purchase.

Oh nope, the actual samsug smartv line(2015 series j). Only have scart in the low models(no smartv). They only hace rca and Y,Cb,Cr/Y,Pb,Pr(shared connectors). In the low line if you have scart, you lost 1 hdmi(3 witouth scart, 2 with scart) and Y,Cb,Cr/Y,Pb,Pr. and maybe not full hd.

In the smartv models they add a crapy cable that converts  scart to rca(red,white yellow). So you not have rgb and youn can't connect the cpc. (except the gx4000 of course)

This change entry this year, the line of 2014(h series) have scart +smart, but you not have dvbt-2 for example. The samsung scart adaptador is no in the new line . I think is related to the annulation in frace of the law of the scart, samsung the first drop it.

SAMSUNG 32J5500 REVIEW, PRET (43J5500 / 48J5500 / 50J5500) : Samsung

Is a chaos the line the 2015(in the connectors) wtf!.

I know because mi old tv is broke and i searching a new one, nobody have s-video more except loeve tv(a very expensive manufacturer from germany). Vga pc is lost except en very very low models, and the tvs now not have pc audio in (except lg(shared with rca) an philips) inclusive if they have dvi case of samsung that say you search an external speakers....

So i interested if syx can made work all cpcs with these adapter

Samsung line not make sense. When i buy a better tv i wait found the same  connectors of the cheap line and add more extra features not lost  connectors!.
« Last Edit: 17:48, 08 December 15 by dragon »

Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #14 on: 18:34, 08 December 15 »
we should really be looking at cheap reliable Y,Cb,Cr/Y,Pb,Pr or HDMI solutions.



We should. Sadly so far all of the SCART to HDMI converters I have tried are absolute rubbish. Laggy with over sharperned pictures. I keep meaning to make a video about them to stop people raving about them when they blatantly have major picture quality and delay issues.


Best quality I've seen is using a Pioneer DVD recorder as an in-line converter taking the RGB and deinterlacing and converting it to HDMI or Component. But the delay is still an issue. Easy to tell as if you turn the CPC's speaker up and press delete on the start screen, the speaker will play fractionally before the TV does. With a Spectrum with all its clicks and fart noises its even more obvious.


I have a GBS board sitting on my desk that I bought for the PPC (doesn't work due to sync issues) which might convert CPC RGB to VGA. Haven't tried it though.



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Offline dragon

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Re: Is there differences between CPC and CPC+ video output???
« Reply #15 on: 19:58, 08 December 15 »
Googling  i found this project:

https://www.google.es/url?sa=t&source=web&rct=j&url=https://github.com/MusicMiK/RGB-YPbPr&ved=0ahUKEwjHoYKD6czJAhXIVj4KHRqFB6Q4FBAWCDIwBw&usg=AFQjCNHETkfLRyEPdVtXb-UG66Td9SSTLg&sig2=eRUuSJwg_uRRHQO0AhlsXA
https://www.google.es/url?sa=t&source=web&rct=j&url=https://github.com/MusicMiK/RGB-YPbPr&ved=0ahUKEwjHoYKD6czJAhXIVj4KHRqFB6Q4FBAWCDIwBw&usg=AFQjCNHETkfLRyEPdVtXb-UG66Td9SSTLg&sig2=eRUuSJwg_uRRHQO0AhlsXA

If all are bad conveters maybe is not best build one made to the cpc?

Offline andycadley

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Re: Is there differences between CPC and CPC+ video output???
« Reply #16 on: 20:11, 08 December 15 »
* andycadley clings tightly to my CM14....

Offline chinnyhill10

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Re: Is there differences between CPC and CPC+ video output???
« Reply #17 on: 20:31, 08 December 15 »
Googling  i found this project:

https://www.google.es/url?sa=t&source=web&rct=j&url=https://github.com/MusicMiK/RGB-YPbPr&ved=0ahUKEwjHoYKD6czJAhXIVj4KHRqFB6Q4FBAWCDIwBw&usg=AFQjCNHETkfLRyEPdVtXb-UG66Td9SSTLg&sig2=eRUuSJwg_uRRHQO0AhlsXA
https://www.google.es/url?sa=t&source=web&rct=j&url=https://github.com/MusicMiK/RGB-YPbPr&ved=0ahUKEwjHoYKD6czJAhXIVj4KHRqFB6Q4FBAWCDIwBw&usg=AFQjCNHETkfLRyEPdVtXb-UG66Td9SSTLg&sig2=eRUuSJwg_uRRHQO0AhlsXA

If all are bad conveters maybe is not best build one made to the cpc?


To be honest the best option is probably just to bite the bullet and buy a Framemeister. But they aren't cheap.About £200. But they will be what we all end up with eventually as they seem to cope with anything and everything thrown at them with no lag or distortion. But expensive.
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Offline Bryce

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Re: Is there differences between CPC and CPC+ video output???
« Reply #18 on: 22:29, 08 December 15 »
Converting RGB to YPbPr isn't actually all that difficult as it needs no frame sampling/storing and can all be done in realtime (ie: no lag) with a few transistors or opamps. It has minor advantages over SCART, but again, that will depend on how the TV is decoding the signal and could potentially have the same sync issues as SCART on some TVs.
I'm not sure if I have a TV with a YPbPr port, but if I do, I might make up a small circuit and check it out.
HDMI is considerably more complicated and expensive to do.

Bryce.

Offline OCT

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Re: differences between CPC and CPC+ video output
« Reply #19 on: 07:14, 03 January 16 »
Converting RGB to YPbPr isn't actually all that difficult as it needs no frame sampling/storing and can all be done in realtime (ie: no lag) with a few transistors or opamps. It has minor advantages over SCART, but again, that will depend on how the TV is decoding the signal and could potentially have the same sync issues as SCART on some TVs.
I recall when debugging an early AD724 modulator, you also pointed out how 220pf capacitors on the color lines (like the Classic CPCs used to have) might improve the Plus signal from the Limited batch of new S-Video Adapters.
Amstrad Action in 6/1989 approx. recommended resistors in line (100 ohms or so if memory serves) for SCART from some CPCs to certain TVs.
« Last Edit: 07:15, 03 January 16 by OCT »