Bouncing screen on STF with RGB Scart

Troubles with your machine? Just want to speak about the latest improvements? This is the place!

Moderators: Mug UK, Zorro 2, Greenious, spiny, Moderator Team

walterg74
Atari nerd
Atari nerd
Posts: 47
Joined: Sun Jul 17, 2016 8:57 pm

Re: Bouncing screen on STF with RGB Scart

Postby walterg74 » Tue Nov 08, 2016 6:42 pm

stedy wrote:
rj1 wrote:I had similar issue on a Mega 1 as OP, where the display would jump diagonally by about 1-2cm every few seconds on one TV (Philips LCD) but would be fine on another TV (Sharp LCD).
I added a 1N4148 diode and a 10uF capacitor for the BLANKING SCART pin 16 as on your schematic and it solved the issue.


:D it appears to work.

walterg74 wrote:
Hi Ian, should this one work on an STf ? I could not get it to work with any of my cables, on a 1084S-D2 monitor (not with scart + scart/db-9 adapter, not with direct philips type cable), not with a PVM using scart cable.
Today I luckily acquired an SM124 and image came up fine, so Atari should be working correctly (side note, the othe monitors and cables work fine with my other Ataris).

Give it a try, the switch + 2 resistors on the CSYNC signal should cater for all eventualities.
A Sony PVM should work fine with Hsync/Vsync, they do tolerate a reasonable amount of variation on TTL Csync too.


thanks for the reply. I have 3 Sony PVMs (they just have the one external sync thouh, not separate h + v).

When using those switching sync on and off I did see the screen appear briefly, so something is getting there but not quite right, so maybe they don't tolerate that much?

I was thinking I can also try addind the resistor inside the scart casing of the cable I already have as a test.

If that doesn't work (or even if it does) I will go ahead and buld my cable from scratch following the model.

walterg74
Atari nerd
Atari nerd
Posts: 47
Joined: Sun Jul 17, 2016 8:57 pm

Re: Bouncing screen on STF with RGB Scart

Postby walterg74 » Fri Jan 20, 2017 11:04 pm

stedy wrote:
rj1 wrote:
walterg74 wrote:
Hi Ian, should this one work on an STf ? I could not get it to work with any of my cables, on a 1084S-D2 monitor (not with scart + scart/db-9 adapter, not with direct philips type cable), not with a PVM using scart cable.
Today I luckily acquired an SM124 and image came up fine, so Atari should be working correctly (side note, the othe monitors and cables work fine with my other Ataris).

Give it a try, the switch + 2 resistors on the CSYNC signal should cater for all eventualities.
A Sony PVM should work fine with Hsync/Vsync, they do tolerate a reasonable amount of variation on TTL Csync too.



Oops.. never got the alert you had replied :(

What do you mean about the pvm and hsync/vsync? The pvms I have only have a single bnc input for sync. Or did you mean to tie them together in some way?

Maeke
Captain Atari
Captain Atari
Posts: 305
Joined: Sun Mar 13, 2016 1:54 pm

Re: Bouncing screen on STF with RGB Scart

Postby Maeke » Thu Jan 26, 2017 9:17 am

EstTeeEfEm wrote:I know the composite signal is present because my STFM works without a problem, but this STF shows no picture that way. The guy I got it from sounds like he's had a lot of experience building these different types of cables so I couldnt presume he'd forgotten anything or added anything extra.
I'd assume he used the extra resistors too from what I can gather. He does produce separate scart cables for STFM's and STE's knowing that they have an RF present.

If your TV has such a switch, then switching it from the state it is in now to the opposite state may clear up your problem.


It has no such switch and is a SHARP if that makes any difference?


Well not all ste have a RF, my french ste doesn't have one, as it was not compatible with french standard (secam).
You do not have the required permissions to view the files attached to this post.

ScooberDiver
Atarian
Atarian
Posts: 5
Joined: Thu Oct 19, 2017 3:56 am

Re: Bouncing screen on STF with RGB Scart

Postby ScooberDiver » Wed Nov 22, 2017 8:36 pm

I figured out my STf does not have CSync on the monitor connector so it needed an addition to the fine circuit shown earlier. I combined HSync with VSync using the circuit I'm attaching to this message as a picture. I had a 2N4124 transistor laying around but any NPN transistor should work.
Sync combiner is from:
http://www.nexusuk.org/projects/vga2scart/circuit

I didn't need 12v as my scaler doesn't care about aspect ratio selection. It does need the 1-3v for RGB selection and Steddy's diode+capacitor does the trick even with VSync driving two circuits.
I managed to squeeze it all into the SCART connector. Attached is a photo before connecting wires. That must be the world's smallest electrolytic capacitor!

Component Type
R1 3.3K Ohm
R2 1.2K Ohm
R3 820 Ohm
R4 68 Ohm
Q1 BC548B

schem.png
You do not have the required permissions to view the files attached to this post.
Last edited by ScooberDiver on Thu Nov 23, 2017 4:00 am, edited 1 time in total.

ScooberDiver
Atarian
Atarian
Posts: 5
Joined: Thu Oct 19, 2017 3:56 am

Re: Bouncing screen on STF with RGB Scart

Postby ScooberDiver » Wed Nov 22, 2017 8:44 pm

And if anyone is wondering, that's a 22uF / 16v capacitor.
Diode is 1N4148.
100 ohm resistors are in series with red green blue.


Social Media

     

Return to “Hardware”

Who is online

Users browsing this forum: No registered users and 8 guests