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ballzdeepx
11-22-2014, 07:33 PM
Hey all,
So I'm trying to get my consoles working via rgb/scart but have hit a wall.

I have a PVM 2950 which from everything I've read required a LM1881 stripper/cleaner on it to display.

All of my console scart cables look to use pin 20 for video

I'm using a scart switch

For my display cable I have a scart to BNC (R/G/B/Sync) and I'm wiring the stripper in the hood of it.

I've built the circuit as shown here
http://www.mmmonkey.co.uk/composite-sync-stripper-lm1881/



On the display cable: (goes from switch output to TV)
Im going pin 20 from scart hood>Input of amp>Output of amp>black wire of BNC/Sync line
I have +5v tapped from pin 8 (which also is bridged to pin 16)
I'm using Pin 18 for ground (which is also bridged to pin 4) this cable was already using this pin for ground and to the hood shield

All I can get is a rolling screen, If I'm using my mega everdrive for example, the startup screen is rolling, i get some sold colors on screen as it boots, then the rom list is scrolling. This also happens on my DuoR for example.

Any advice is appreciated,
Thanks!

ballzdeepx
11-22-2014, 08:56 PM
Well hours wasted but finally traced it down to being an issue with the input on the scart switch.
I never thought to try a different input on it to see if that would matter.

:keke:

There goes 5 hours of time I'll never get back.

Atro
11-22-2014, 09:50 PM
As for the scart switch, have you checked it too?

Cold solder joint? broken trace? fried diode?
It's weird, those things don't break that easily.

ballzdeepx
11-22-2014, 09:59 PM
I haven't checked into that yet Atro but probably will at some point.

I should also mention I changed the display cable to use pin 19 instead of 20, and also unbridged 16 and 8, and am now just using pin 8 for the 5v needed for the circuit. This might not have done much, it may have, but just putting it here for future reference.

Xian Xi
11-23-2014, 03:30 AM
It's not going to auto sync. You might still need to tune the sync on the PVM itself.

theMot
11-23-2014, 05:02 AM
It's not going to auto sync. You might still need to tune the sync on the PVM itself.

Pvm 2950 doesn't have adjustments for sync. If you use lm1881 it will work though.

Jassin000
11-23-2014, 05:13 AM
Not all consoles will require sync stripping... SNES, PS1, Saturn for example all output a perfectly working sync directly on my 14L5. I would only place LM1881's into the cables of the consoles that require them before the switch... Neo-Geo, Genesis for example and not the main video out to PVM cable.

theMot
11-23-2014, 06:11 AM
Not all consoles will require sync stripping... SNES, PS1, Saturn for example all output a perfectly working sync directly on my 14L5. I would only place LM1881's into the cables of the consoles that require them before the switch... Neo-Geo, Genesis for example and not the main video out to PVM cable.

They all need it on the 2950. No lm1881, no work.

BladeDancer314
11-23-2014, 09:01 AM
Not all consoles will require sync stripping... SNES, PS1, Saturn for example all output a perfectly working sync directly on my 14L5. I would only place LM1881's into the cables of the consoles that require them before the switch... Neo-Geo, Genesis for example and not the main video out to PVM cable.

My 14L5 and 20L5 needed sync stripping on almost every console, I think the dreamcast was the only one that worked fine.

Skips
11-23-2014, 10:36 AM
Not all consoles will require sync stripping... SNES, PS1, Saturn for example all output a perfectly working sync directly on my 14L5. I would only place LM1881's into the cables of the consoles that require them before the switch... Neo-Geo, Genesis for example and not the main video out to PVM cable.

It really just depends on the monitor. Most PVM models will work just fine if you feed them composite sync from the console instead of composite video however there are some monitors that require a sync stripper regardless. That little PVM-1271Q I have for instance requires some sort of sync stripper or it wont work at all, even when using composite sync. The 14L5 and 20L5 are not really picky. My 20L5 I used to have would take pretty much any sync signal I gave it, whether it be composite sync or composite video.

Jassin000
11-23-2014, 01:59 PM
Huh thats interesting... I've only worked with the 14L5 but when it came to sync I just figured they were all more or less the same.

I would love to get my hands on a 20L5, they seem pretty rare tho.

Atro
11-23-2014, 06:19 PM
I had sync issues on my new Thomson CRT with my AES.

Didn't required to add a sync cleaner tho.
I just desoldered the Composite from the DIN8 pin3 and attached it to pin7.

All sync issues were gone just like that :)
Composite is gone now, but who cares? As Broken says "RGB for the People!"

BladeDancer314
11-24-2014, 01:43 PM
This is the issue I had, every conosole was doing it.


https://www.youtube.com/watch?v=eMzy9mZNUuw&list=UU3D9drrRfAxZxR5--sb4MXw

chrisdc123
12-01-2014, 06:51 PM
They all need it on the 2950. No lm1881, no work.

Actually, I've used SNES with the console's own composite-sync directly wired to the 2950, without a sync cleaner, and had no problem.

ballzdeepx
12-01-2014, 07:17 PM
I had sync issues on my new Thomson CRT with my AES.

Didn't required to add a sync cleaner tho.
I just desoldered the Composite from the DIN8 pin3 and attached it to pin7.

All sync issues were gone just like that :)
Composite is gone now, but who cares? As Broken says "RGB for the People!"

Interesting,
My MVS 2 slot sometimes has intermittent sync issues still, It would blink every 2 seconds but I got around it by using a 100 ohm resistor on pin 3 as my reasoning was because the colors are so bright, the sync must also be coming in super high as well. I actually had to tap off the JROK Cvid output that was in this unit to begin with (just tapping sync from the mvs board didnt work, nor did adding the resistor in line from that tap either). I never tried not using C vid as a sync at all, maybe that will fix it for good as it still happens on some games when the screens change.