Newbie question: Sync problems when connecting to TV/Monitor

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Eratosthenes
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Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 21:46

Hi there,

to me the ZX-UNO is a great piece of hardware as it allows me to use any ZX Spectrum I can imagine as if it's real.

As an absolute newbie though (got my ZX-UNO today :D ) I've got issues connecting the device to my TV or monitors.

I think this issue has been discussed here several times but as I can't speak spanish I'm not able to use the search function... :(

1.: using RGB I've got massive synchronisation problems
2.: using VGA the TV says "incompatible mode" and "can't be displayed"

The more black is shown the bigger problems I have. If for example BORDER 0 is used the display is completely unsynced.

Added to this post some screenshots showing the problem.
uno_rgb01.jpg
B/W picture, nearly OK. The picture is moved slightly to the left, having a black stripe on the right. Just minor sync errors at the very top right of the screen.
uno_rgb02.jpg
Using black background makes creates sync errors.
uno_rgb03.jpg
ZX-UNO BIOS V0.63 is used...

Are there any hints how I can use my ZX-UNO?

Thanks for the info.
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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antoniovillena
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por antoniovillena » 14 Sep 2017, 21:53

1. About RGB problem use CSYNC.TAP
2. About VGA problem. Press ScrollLock 1 or 2 times. If you can see video is because your monitor accepts 60Hz. Go to the BIOS and put VGA output and 60Hz. And low the frequency until you have sync problems again. The frequency is proportional to the speed, so at 55Hz you will have a zx spectrum accelerated at 110%

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Eratosthenes
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 21:56

Hi,

this was a very(!) quick response... :D

(Not sure if CSYNC.TAP already is on my memory card. - If not, where can I get it?)

THNX a lot...
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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Eratosthenes
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 22:00

P.S.: Finally I saw that you added a link... ;->

P^2.S.: Now, after using CSYNC, I've got a headache as the screen has flickered a lot when changing the 3rd setting.
The rest (48k, 128k) hasn't had any effects except of two lines crossing the screen.

Maybe it's an issue of my TV set... :(
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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Eratosthenes
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 22:36

One more question: As the picture of the ZX-UNO is much brighter as any other device I've connected to the TV:
Could it be that the signal level of the ZX-UNO is somehow off the scale (==to high)?

I think this could be a reason why the TV isn't able to sync especially when the contrast is to high...
Última edición por Eratosthenes el 14 Sep 2017, 22:47, editado 1 vez en total.
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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antoniovillena
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por antoniovillena » 14 Sep 2017, 22:44

Eratosthenes escribió:One more question: As the picture of the ZX-UNO is much brighter as any other device I've connected to the TV:
Could it be that the signal level of the ZX-UNO is somehow of the scale (==to high)?

I think this could be a reason why the TV isn't able to sync especially when the contrast is to high...
The signal is 100% bright for Scart cable and 72% for VGA pasive cable. The VGA active one is also 100%. The active cables just adapt the impedances, there is no amplification (gain is 1).

Note: 100% bright means 0.7Vpp

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Eratosthenes
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 22:50

Yes but what is interesting though: If I'm using blue on any other background as black, everything is OK.

Anytime I'm using black the signal is desynced. I've got an oscilloscope somewhere in my cellar. Maybe tomorrow I will measure a bit. :D

(Or I simply will add some resistors to the RGB cable. As far as I remember the sync signals are added to the green signal, aren't they? So if the signal is 100% maybe the sync signal is cut because it will be cut off by the TV. As far as I remember black is the highest voltage level...)
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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antoniovillena
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por antoniovillena » 14 Sep 2017, 22:57

Eratosthenes escribió:Yes but what is interesting though: If I'm using blue on any other background as black, everything is OK.

Anytime I'm using black the signal is desynced a bit. I've got an oscilloscope somewhere in my cellar. Maybe tomorrow I will measure a bit. :D

(Or I simply will add some resistors to the RGB cable. As far as I remember the sync signals are added to the green signal, aren't they?)
Maybe there is a type of incompatibility between the Scart cable and your TV (assuming CSYNC.TAP doesn't solve the problem). I've similar problem with another zxuno user and finally I fixed it thanks to the suggestion of McLeod (the designer of the RGB circuit). If you'll try with resistors, try also with capacitors (about 1uF will suffice). Of course if we can not find a solution I'll refund the Scart cable.

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Eratosthenes
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por Eratosthenes » 14 Sep 2017, 23:02

I definitely don't need any refunds. - But thanks for this... :D

I'm nearly sure that a resistor will do the job. Using capacitive impedance will "kill" the signal. I will let you know...

P.S.: Maybe a signal level of 80% - 90% would be a better idea cause of compatibility reasons. (Or does the next ZX-UNO support 40-bit HDR?! :D )
Nine out of ten voices in my head say: "You're not mad!" - The tenth humming the melody of Pong <click> ...

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antoniovillena
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Re: Newbie question: Sync problems when connecting to TV/Monitor

Mensaje por antoniovillena » 14 Sep 2017, 23:15

Eratosthenes escribió:I definitely don't need any refunds. - But thanks for this... :D

I'm nearly sure that a resistor will do the job. Using capacitive impedance will "kill" the signal. I will let you know...

P.S.: Maybe a signal level of 80% - 90% would be a better idea cause of compatibility reasons. (Or does the next ZX-UNO support 40-bit HDR?! :D )
Ok. If no refund at least I promise to find a solution for this TV. In the worst scenario I can convert into a passive one (you'll see the image a little darker).

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