Question regarding sync signals from nesrgb

[HermanMunster]

Hi, I am new to this forum. I have asked this same question in two other forums but have not got a single reply yet. The shmups forum seems to have more hardware-related topics, so this might be the best place to ask for help. Here is the issue I'm having:

A few months ago I did the nesrgb mod on my PAL nes console. Back then the console was working perfectly fine with no issues whatsoever. It has been probably about 2 months since the las time I used it. Yesterday I played Probotector through my ossc for about 1 hour without any problems, but after an hour or so, I suddenly lost video and audio signals while the ossc displayed "no sync". I tried turning the console off and back on, but still nothing happened. I used 3 different scart cables but still couldn't get my ossc to recognize the signal coming out of my NES. (I am using high quality male to male scart cables since my consoles all have female scart plugs built in)

To make sure that the ossc was working properly, I tested it with my PAL snes console and everything worked fine.

I then tested the voltages on different pins of the scart cable coming out of the nesgrb console to make sure that an actual signal was coming out of the console. The red, green and blue lines were all in the 0,6 volts range. Pins 8 and 16 (rgb switching) were in the 5v-6v range. The csync pin 20 had a 0,6 voltage as well.

I also opened up the console, inspected the board checked all the connections with a multimeter, and everything looked fine.

It looks like the ossc doesn't recognize the csync signal coming out of the console? Is there anything that I could do to fix this? I had soldered jumper j8 on the nesrgb board when I did the mod. I dont know if this has anything to do with the problem.

Could opening jumper j8 and adding instead a 470ohm resistor in series to the csync line fix the problem? Maybe too much of the csync signal is escaping to ground through the 75ohm resistor habilitated by shorting J8?

[unmaker]

Having "no sync" displayed on the OSSC does not necessarily mean your issue is sync related. You'll get that message if your console is powered off for example. To rule out other potential problems, are you able to output in composite and/or s-video?

Also what sorts of scart cables are you using? If you've bridged J8 then you'll want to use a pass-through cable with no resistor on the csync line. If your cable has a series resistor on the csync line then you'll want to open J8.

[HermanMunster]

Hi, thanks for your answer! Now it is working intermittently; sometimes it recognizes te signal, sometimes it does nothing. My cable is an individually shielded male to male Philips scart cable with no resistors in any of the lines. Max resistance is 0,2 ohm as measured with my multimeter. Yesterday I spent about half an hour playing probotector without an issue, and all of the sudden I lost video and audio again and got the "no sync" message. I wonder if there is something wrong with the nesrgb board? I checked continuity on everything and it all looked good.

[Kez]

Are you using an official PSU? Also did you fit the voltage regulator board that comes with the kit?

[HermanMunster]

I forgot to mention that I have installed the blinking light win cartridge connector on this console as well. I do not know if it is compatible with the nesrgb board, but as far as I know there shouldn't be a problem right?

[HermanMunster]

Are you using an official PSU? Also did you fit the voltage regulator board that comes with the kit?

Yes, I am using the voltage regulator that came with the board, and I also replaced the voltage regulator on the console with a brand new one. The psu that I am using is a high quality 9v dc 1,4 amps class VI unit that I bought on digikey. I have used the same psu with my other consoles and havent had am issue. I do have the original psu, but dont want to use it because last time I checked it outputted 14,89 volts, wich is way out of spec.

[unmaker]

There is no compatibility issue between the BLW and NESRGB.

How are you connecting a male to male scart cable to your NES? I think you may simply be having a poor connection.

[HermanMunster]

There is no compatibility issue between the BLW and NESRGB.

How are you connecting a male to male scart cable to your NES? I think you may simply be having a poor connection.

Like this:

[HermanMunster]

I don't think there could be a connection issue; I tested continuity on everything! And as I said in the previous post, I also tested all rgbs signals coming out of the scart cable and all voltages were between acceptable ranges. I also thought that maybe there could be an issue with the scart plug on the ossc, but it does work with other consoles, so this shouldn't be the problem.

[HermanMunster]

Ok, I did sone more tensting. At first, I was connecting the console through the ossc directly. In this case, it worked intermittently. Then, I connected the console through my Philips automatic scart switcher which does not have a light indicating which scart input is active, with the same intermittent results. I lastly connected it through my bandridge automatic scart switcher which does have a light that indicates which scart input is active. In this case, when I turned on the console, the light on the scart switcher goes on, whereas the ossc still displays the 'no sync' message.

This leads me to believe that there is something about the signal coming out of the nesrgb that the ossc does not like and thus doesn't recognize it. Does anybody here have a similar setup? (Nesrgb + ossc). And if so, have you ever had any similar problems? I have the kaiko edition of the ossc which I bought in 2018.

[HermanMunster]

I did some additional testing on the csync line coming out of the console. I measured steady dc voltage again at 0,5 volts. However, when measuring frequency on the csync, it was all over the place and I could not get a stable reading. Shouldn't frequency be 50hz for pal consoles? I think this could be the problem. Any ideas as to why I couldn't get a stable frequency reading? Any help would be much appreciated!!!