RGB Monitor Sync/Image issue, JVC DT-V2000SU

[SnakeGrunger]

Hi everyone,

I've been struggling for a while with a RGB monitor and I'm starting to run out of ideas.

Here's what's happening : I have a JVC DT-V2000SU 20 inch RGB monitor with R/G/B/Cs inputs at the back.
I have a stock Phat NTSC SNES with an Scart (Csync) cable purchased from retrogamingcables.

Power on the monitor, power on the console, sync kicks in: stunning, stable image.

But herein lies the problem : I unplug everything and try the same but with my Genesis Model 2 and Scart cable purchased from the same site, and no image.

I have a PVM-2030 as well, and my same Genesis and cable kick in wonderfully.

So I checked the official JVC service manual and stumbled across this information on page 22:

-EXT SYNC (HD/Cs, VD) input
1 line, BNC connector x 4 (bridge connection possible, auto termination)
Horizontal/composite synchronization signal
HD : 1 — 4 Vp-p, 75
Cs : 1 — 4 Vp-p, 75

So I checked the scart plugs and here is what I found:
SNES NTSC : Straight-through sync line
GEN2 NTSC : 470Ω and 220μF (6.3v) in series

I took the oscilloscope and took these measurements with the cable plugged into the monitor on the GEN2 sync line (before and after the resistor), SNES and FamicomAV modded with eTim's board.

I replaced the 470Ω resistor with a 75Ω one and I got a garbled SEGA logo when booting a game, and after a few seconds sync kicked in!... BUT that was 2 weeks ago. I tried again today and no sync whatsoever with the GEN2.

I also replaced the 220μF capacitor with a brand new 25V one from digikey, still no sync, or sync "OUT OF RANGE".

Any thoughts guys ? Is there something defective inside the monitor ? Or am I not setting the right voltage for the sync line going in ?

[Xer Xian]

Nice monitor you've got there! It's basically the father of mine (JVC DT-V1710), and I didn't even know it existed before reading here

Sorry I can't be of much help. On retroRGB you can find the components required to get 75 ohm sync from the Genesis - it seems to me that you can keep the resistor as is and change the capacitor with the other one you've got. That said, these monitors should be able to accept TTL sync without problems.

[SnakeGrunger]

Nice monitor you've got there! It's basically the father of mine (JVC DT-V1710), and I didn't even know it existed before reading here

Sorry I can't be of much help. On retroRGB you can find the components required to get 75 ohm sync from the Genesis - it seems to me that you can keep the resistor as is and change the capacitor with the other one you've got. That said, these monitors should be able to accept TTL sync without problems.

Thanks man, I already tried with 75 in series (and 62, and 100, and 330ohms, same thing) and with a brand new 220uF capacitor. I'll try a 330uF one and see!

[xAzurexEonx]

The Sega Genesis cable was properly wired for CSync.

How are you connecting these? The 2030 uses a 25 pin type and JVC is bnc inputs. So somewhere you have adapter to one or the other,this could be the failure point.

[SnakeGrunger]

The Sega Genesis cable was properly wired for CSync.

How are you connecting these? The 2030 uses a 25 pin type and JVC is bnc inputs. So somewhere you have adapter to one or the other,this could be the failure point.

I have a Scart female -> BNC as well as Scart female -> 25 pin for both monitors, both by Retrogamingcables once more.
I tried with 2 other Scart female -> BNC splitters from two other monitors I have, as well as with another Gen2 console and Gen2 scart cable wired for CSync from RGC, and still no sync.

[xAzurexEonx]

Okay so it sounds like this monitor behaves the same way as the 20F1U where it had issues with Sega and Neo Geo stuff. Believe you can try and find info if you search for the Sony forum about it, I do believe it is a mod to the Gen board.

[SnakeGrunger]

Okay so it sounds like this monitor behaves the same way as the 20F1U where it had issues with Sega and Neo Geo stuff. Believe you can try and find info if you search for the Sony forum about it, I do believe it is a mod to the Gen board.

What sucks is that after changing the resistor on the sync line in the scart plug to 75 ohm, I got sync then my friend who owns the monitor came by and I showed it to him and it still worked, but when I powered it on again two days ago it didn't sync at all.

I will try 75ohm termination plugs on the BNC pass-through holes, and I will also try my NeoGeo as well later tonight!

[SnakeGrunger]

I found this post by vileTim which seems to suggest the best solution : Get a SyncStrike from ArcadeForge

viewtopic.php?p=1219648#p1219648

[xAzurexEonx]

I found this post by vileTim which seems to suggest the best solution : Get a SyncStrike from ArcadeForge

viewtopic.php?p=1219648#p1219648

yes this is one of the posts I recall seeing an issue close to what you are dealing with.

Keep us posted.

[lewolfeur]

Yes was released two year before DT-V1900/1700 and its also a shadow mask tube and not compatible with pal/secam standard (so was never released in europe).

Was thinking to buy a oscilloscope for test the sync for my 1990r, the ds1054z is a good one ?

[xAzurexEonx]

Yes was released two year before 1900/1700.

Was thinking to buy a oscilloscope for test the sync for my 1990r, the ds1054z is a good ?

Thanks for the info. Was wondering if this model was newer or older than the 1700/1900 series. Shame this looks like this is the only model with an actual 20" screen.

[SnakeGrunger]

Just to confirm : I purchased a SyncStrike from ArcageForge, and now every single RGB connection I plug in there displays perfectly on the monitor. It is absolutely gorgeous <3