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Dloop

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So I got my CPS2 and Darksoft Multikit up and running, and it's awesome for the most parts, so to the issue at hand.

If I run sound through the river service jamma harness in my NNC I get sound as usual and everything is fine.

When I want to have stereo sound however, and connect RCA cables to CPS2 RCA contacts and to the amplifier in the NNC, I hardly get any sound.

If I am very quiet, I can hear a very faint sound from the game.

So to the steps that I've already tried:

  • Turning volume knob on cab does nothing
  • Increasing / decreasing sound on CPS2 does nothing
  • Ensuring CPS2 is set to stereo doesn't help
  • Holding volume down for 20 sec on boot, and then turn volume up, does not help
Not sure what more I can do.

I don't see any switch on the amplifier or cab for any setting that might help.

Is the RCA contacts on my A board broken?
 
Hold down volume UP (not down) on boot.
 
Hold down volume UP (not down) on boot.
Thanks will try that instead tomorrow.

Can you please write what this does? The down button I read was to reset the audio settings for the CPS2.
 
So holding volume up at start did not help, and holding it in 5 sec while running did not help as well.

Again jamma sound works fine regardless if it states stereo or mono in config, but the RCA stereo out does not work for me.

Just the faintest sound that I cannot increase in any way.
 
Interesting.

Is the amplifier in your cab definitely working, regarding its RCA inputs? Can you narrow this down by connecting the CPS2 RCA outs to a different external amplifier, like an old hifi system etc?

I'm sure you're aware but the RCA output is line level and thus needs to be amplified, it's too weak a signal to connect directly to speakers.

If that's not the issue perhaps there's a fault with your A board.
 
Interesting.

Is the amplifier in your cab definitely working, regarding its RCA inputs? Can you narrow this down by connecting the CPS2 RCA outs to a different external amplifier, like an old hifi system etc?

I'm sure you're aware but the RCA output is line level and thus needs to be amplified, it's too weak a signal to connect directly to speakers.

If that's not the issue perhaps there's a fault with your A board.
The amplifier works as the jamma signal goes to the same RCA inputs on the amplifier (due to how the river service jamma harness is built).

Unless the jamma signal does not need to be amplified and the amplifier is just passing it through?

I don't really have an old hifi system anymore, or anything similar.

I'm also guessing something is wrong with the A board, but why would I then hear a slight sound still?

Edit: Will see if I can find other RCA cables to try with as well, just in case.
 
Jamma audio is amplified (speaker level), which explains why that works.

The RCA output is line level, not amplified, thus it would barely be audible if connected to speakers directly sans amplification.

I'm not sure how your cab works but it's not the norm for jamma audio to run through an amplifier. It's not necessary as mentioned before jamma audio is amplified from the game PCB.

Best way to narrow down the issue is to connect the CPS2 RCA outputs to an external amplified source, even a TV would work.
 
So I've uploaded images of how it is connected, so the amplifier can be seen. The gray RCA cables that can be seen is from the jamma harness. When I play jamma they go into the RCA inputs that the CPS2 stereo cables are going to in the pictures.
 

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I'm leaning towards an issue with your cab / amp / wiring than the CPS2 board.

It would help if you could connect the CPS2 RCA outputs to an external source such as a stereo system etc.

Otherwise, to go in the other direction, do you have a Naomi or other arcade hardware with line level RCA output that works fine in your cab when connected the same way?
 
Do you have any other PCB with RCA to test with?
Or perhaps a laptop or MP3 player with 3.5mm jack to RCA?

Also rule out the cable, the original RCA lead is just junk and I had mine going quiet on 1 channel as well and replaced the cable itself.
 
Thank you everyone with the responses and help.

I have two cabs, so today I got off my butt and tried the second cab and lo and behold the stereo sound for CPS2 through RCA works.

So it's cab 1, either the cables (which I don't think since I hear the sound very low, should be no sound at all then) or the soundcard/amp which is more likely :(
 
Replace the cables to be sure, like I said the original is junk and very thin.
If corrosion got in the cable it could result in a high resistance and therefore muted audio.
It is just a straight RCA cable, nothing fancy, sure you have anything lying around ;)

if it is the amp, those are easy and cheap to buy
 
So I went and bought more expensive RCA cables to rule out the cables, but the issue persists.

So guess it's not the cables at least.

Question is what it is then?

The soundcard/amplifier still passes through sound, so it shouldn't be completely broken right?
 
Ebay has lots but also I’m sure members here have spare amps as the NNC is a very common cab.

you could also try to recap your existing one.
Had a similar issue with the amp in my Cyberlead cab, muffled R channel, recappen it and fine again.

might even have a spare NNC amp but would have to check my parts stash :)
 
also to rule out the cables or speakers. You can swap around the L and R channels directly at the amp.

think if I recall correct one of the speakers was blown on my NNC as well when I first got it
 
Thank you for your feedback.

I was able to get a hold of a spare amp, and switching the amp out the stereo RCA sound works as expected.

Not sure what could be the issue, would assume it should work vs not work at all. Not just pass through and not do anything with the signal.

Now the new problem comes in instead :( Every time I start the cab, the really loud POP comes from the speakers.

I do not have this issue with the other cab with a working amp, and did not have it on this cab before either :((((
 
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