Voultar's PCE RGB output issues through SCART switch only

[fernan1234]

Edit: I've ruled out the SCART cable as the source of the problem. It looks like something about Voultar's board may be incompatible with my SCART switch. Would still like to know why.

I just got a Super CDROM2 unit that has been modded with Voultar's latest RGB board. It goes PCE/SCDROM2 -> Retro-Access EURO SCART cable -> multi-standard SCART switchbox (see below) -> switch's JP-21 output to JP-21 SCART to BNC breakout cable -> BVM
I've also tried switch's Euro output -> Euro SCART to D-Sub cable -> Extron 203 Rxi -> BVM

When I connect the PCE with the same cable directly to my OSSC I get a picture without problems, but in the setup above I get this:



The SCART switch is a passive mechanical switch, one of these sold on Taobao: https://item.taobao.com/item.htm?spm=a3 ... aobao_shop

It has been a great switch, with 10 inputs each switchable between JP-21 and EURO input, and with both JP-21 and EURO outputs. Everything I've hooked up to it, including PCEs with older RGB amps, with different sync types and region standards has worked without problems, except for this Voultar board modded console. The JP-21 BNC breakout cable is a leftover from when I had an all JP-21 setup, and sadly I don't have a EURO one to try to connect the PCE to the BVM bypassing the switchbox, but before this I've mixed and matched stuff and it always performs as it should. But with this Voultar board/cable, when I go through the switch, I get the following problems:
-Inaccurate colors as seen in picture above (when going from the switch's EURO output to the OSSC, it looks the same, but when going directly to the OSSC the colors are fine, so it's not a pinout problem).
-Rolling picture/no sync when using one of the two sync options this switch has (I think it can switch between csync and sync on composite, not sure though, but again this is never an issue with my other 8 consoles).
-Activity LED does not turn on on SCART switch when the console is connected and powered on, though it does pass the picture with wrong colors. Strangely, when the SCART cable is half inserted into the switch socket the JPN LED turns on, rather than the EURO LED, but only if no cable is connected to the output sockets. Maybe this means something is off spec with the voltage/signal that the Voultar board and/or cable is sending to the switch?



Does anyone have experience with Voultar's board, and know if it's picky about SCART switches? Thanks again for any ideas!

[Frank_fjs]

At a glance, it looks like a very similar result as to when a Jap21 scart cable is connected to a Euro scart standard device.

[fernan1234]

Thanks for the reply. I thought so at first too, but later I confirmed that the cable is indeed wired for EURO. I remembered that I have an IFU-30 with the same connector, and the cable works fine as a EURO cable with it, so I have ruled out the cable as the source of the issue. There is simply something about Voultar's board that the SCART switch doesn't like.

Does anyone familiar with Voultar's board have any idea of what it is about it that would cause this problem?

[fernan1234]

I also tested connecting both the old RGB amp modded IFU-30 and this new unit with Voultar's mod to my OSSC, and the signal for each is different, respectively: 15.73kHz 60.05Hz and 15.72kHz 60.24Hz.

Does that provide any clues? Which of those is the expected value for PCE RGB output?

[Kez]

Looks to me like you're just missing green, the different frequencies would be more of a sync issue so I doubt it's related.

That being the case, I can't imagine that anything specifically about the mod would cause the problem.. as the three colour channels should be the same.

Perhaps the switch requires voltage on one of the SCART switching pins in order to detect EuroSCART properly, and your mod/cable combination is not activating it.

[fernan1234]

Perhaps the switch requires voltage on one of the SCART switching pins in order to detect EuroSCART properly, and your mod/cable combination is not activating it.

This would make sense. The cable is correctly identified as EuroSCART when connected to my IFU-30 with an old THS7314 amp, so it has to be either the Voultar board+cable combo, or the board alone.

Is this something that could be corrected with a modification to the cable, or is it intrinsic to the way the board works?

[Kez]

Well if this is the issue, it's more with the installation than the mod board itself. It would simply be a case of tapping 5V from somewhere and wiring it to the corresponding pin on the DIN out. Like in the below:

[fernan1234]

Someone did this mod for me, and according to him the DIN connector gets ground and 5V from the board, so that shouldn't be the problem. He doesn't know what it is about it that doesn't seem to work with my SCART switch.

Maybe the only hope is for Voultar himself to see this thread and he may have a clue as to what's going on.

[maxtherabbit]

Someone did this mod for me, and according to him the DIN connector gets ground and 5V from the board, so that shouldn't be the problem. He doesn't know what it is about it that doesn't seem to work with my SCART switch.

Maybe the only hope is for Voultar himself to see this thread and he may have a clue as to what's going on.

did you tone out the cable to verify that the +5VDC is making it all the way to the correct pin on the SCART head?

[fernan1234]

did you tone out the cable to verify that the +5VDC is making it all the way to the correct pin on the SCART head?

I haven't opened up the cable and probably won't since I may end up returning it if this mod doesn't work for me, but I did test the cable outputting from another PCE with an old 7314 amp and the cable is detected perfectly by my switch in that case, and passes the image as expected, so I think this really narrows it down to the board or the board install.

[dseleski]

Someone did this mod for me, and according to him the DIN connector gets ground and 5V from the board, so that shouldn't be the problem. He doesn't know what it is about it that doesn't seem to work with my SCART switch.

Maybe the only hope is for Voultar himself to see this thread and he may have a clue as to what's going on.

did you tone out the cable to verify that the +5VDC is making it all the way to the correct pin on the SCART head?

I’m going to guess that it does: it successfully switches the mode over to SCART when used with another mod.

Could be something super weird with maybe a slightly lower voltage from that particular console vs IFU-30, though there’s such a range of voltages that can exist on pin 8/16 to trigger a potential mode switch that the manufacturers would be daft to not consider the full potential range.

Scratch that I doubt it triggers on pin 16 (blanking pin is identical in Scart/JP-21) it’ll be pin 8 or maybe detecting sync present or not on pin 9...

(pin 9 would make the most sense really - gives you compatibility with the rare case scenario of non RGB SCART, but still would not remotely explain why this console+mod+cable combo does not switch over to SCART).

I don’t know how these SCART/JP21 switchboxes work in other words, I’m guessing. I don’t know how they detect the pinout. Pure speculation therefore on my part. Personally, given the vast differences in pinout between Scart and JP-21 and potential failure of detection/failure of this hardware causing a short, i’m a bit iffy about this switchbox.

So you can return the cable for more thorough ruling out of a potential cable issue but it’s a real head scratcher all round, given at this point (the second console working) I doubt it’s the cable.

I also doubt it’s anyone’s fault really, nobody in this mix owns all the other pieces of hardware and until one of us does: can’t really diagnose it.

Edit: said pin 11, meant pin 9.

[fernan1234]

Yeah this is really puzzling. I'm ready to also rule out something particular about the switchbox itself because the guy who did the install says he actually just found he has the same problem when hooking up another console with the same board install to his Hydra switch. I guess he had only tested with the OSSC.

[dseleski]

A potential fix for Hydra Switch (and another guess but: a more educated one based on reports in my email.)

If the mod uses csync, increase the csync voltage enough to still be in safe range under 1vpp but a tad higher than it is already: ergo, the 75 ohm sync output resistor: swap it out for a *bit* lower value. don’t ask me what, but it’s worth testing what this trigger range is if you can scope it and have a Hydra Switch. (I don’t.)

Hydra has thrown up issues with lower ranges of csync voltage on other stuff. It triggers on the sync voltage. Case in point: Snes csync w/470 ohm resistor: didn’t apparently work. With 330: worked.

[dseleski]

If the hydra has this issue (which is almost certainly sync voltage just based off of numerous conversations I’ve had with buyers) then I wonder if the other switchbox also has the same problem, albeit if so it doesn’t make a lick of sense tbh.

Most sensible (IMO) way to detect SCART or JP-21 would be to go from pin 9 which in SCART cables is either a ground pin or not connected, in JP-21 is always sync, either csync, composite video, or luma.

Clearly the box is not doing that. Otherwise it would auto detect this this cable - with ground on pin 9 is definitely SCART.

If it’s going from looking for sync on pin 20, there’s a problem with that. Pin 20 is blue on JP-21, should be 0.7vpp. It’s sync on Scart, could be anything from 0.2vpp-1vpp. Trying to find a sync pulse on that pin to detect SCART would make more sense than going off simply looking for a signal full stop, and quite why it wouldn’t trigger if it’s under a certain level just throws up complications, albeit the standard for SCART is to have composite video on that pin so you might surmise, maybe it needs the signal to be over 0.7vpp - however there’s no way some of our csync scarts run as high as that.

I’m surmising this *might* be the problem though. It’s looking for sync on the pin and the signal needs to be over a certain level to trigger.

There might be similar components in it to do the detection as there is in the hydra. If the hydra is fabricated in China... honestly I wouldn’t be surprised if they pulled ideas off some of the guts of it to make this switchbox.

This is pure speculation mind but if your modder understands this stuff, try increasing the sync voltage by a - I’m guessing very small amount. That’s what seems to fix the problem for the hydra.

(imo it’s still a fairly ridiculous way to detect the pinout - pin 9 would be my obvious choice.)

And it’s not Voultar’s fault btw, it’s not the fault of anyone whose mods don’t trigger hydra/this switch.

The switch manufacturers should do their due diligence - csync is massively popular in the hobby and it’s in fact normal and correct for it to go as low as 0.2vpp. I try to shoot for higher levels of sync because we know there’s issues like this out there. But... this is because people use weird stuff and I donlt like having to buy up every available piece of tech - it gets expensive and not cost effective (sadly it’s usually easier to just ask people to return the cable, but it does feel like a cop out.)

As far as I know gscart has none of these problems.

A sync stripper adaptor *may* solve your problem with the idea it’d be used just to boost the sync voltage - but only if I am right. If we use one with a resistor to get csync around the level that we know works (tell me what other csync cables you have that work). I’m actually really curious about this now, so can I send you one to test?

[fernan1234]

Thanks dseleski that's really good info. I ended up sending back the modded unit so the modder will be doing more testing on it, and I'll pass this along. It does sound like an issue of inadequate sync voltage for switches like these two, rather than a region standard detection issue, since it happened with both types of cables tested on my switch, and with his Euro SCART Hydra switch.

Neither of us have a gscartsw to test on it, but I bet it's more likely to work on it. I'll ask him if he has a sync stripper to test, or if he'd like you to send it to him to try out.