Naomi Universal Cab - Audio, IO + NetDimm Issues - Help!

[daveheats]

Hi all. So I'm having a bit of a nightmare with this Naomi cab I got last week. Long story short, I bought a Naomi 2 & NetDimm set up months ago in preparation, and turns out the Naomi 2 was kaput. I've now got a Naomi 1 in there which is working, but I'm experiencing quite a few issues so far with the cab itself:

1 - Audio Buzz - Ground Loop?
So there is really bad buzz through the speakers when the RCA cables are plugged into the motherboard. When unplugged, there is none. I've found one ground cable that wasn't connected to the chassis at the back of the base, cleaned up the ground thread area, reconnected it and still no joy. Also just had a new set of high quality RCA cables arrive but no change. Amp is securely bolted down to the chassis.

I've seen mention of there potentially being dry solder joints / bad caps on the amp board, but is there anything else I can first?

2 - Player 1 - Constant down input
Trying to play Virtua Tennis, it's immediately apparent that Player 1 is stuck with a constant down input, so it's pretty unplayable. Player 2 seems fine. Even when the P1 Stick is wiring is disconnected it still just constantly moves downwards.

Is this potentially a faulty IO board?

3 - NetDimm NetPi - Wont load games
So the NetDimm boots OK onto the cab, where it says searching for network etc. On my phone I can then tap on any game, it goes through the loading process on my phone, gets to 100% and then just goes back to the game list, with absolutely nothing changing on the monitor.

Any pointers on how to get this working?

Thanks so much for any help on the above queries. This is my first cab, so apologies if there is some newbie errors in the above wall of text.
All the best,
Dave

 

[big10p]

2 definitely sounds like an IO board fault. Had this happen a few times in the short period I owned a Naomi. Seems like a common issue, from what I've heard.

 

[jerryspaghetti]

2. Would be faulty io as mentioned

3. You need to make sure the network settings match which they probably do if it’s loading. Next you need the jumpers in net dimm to be set correctly. And you need the zero pic chip in the net dimm.

 

[daveheats]

Thanks for the help so far 👍 Good news is i got the NetDimm working today. Just needed to update the IP address on the Naomi settings.

Still no luck with the audio buzz yet, and will investigate the IO issue this weekend too.

Just chuffed one issue is sorted tbh!

 

[grobda]

I've got a naomi i/o with a stuck output on player 2. I believe its one of the filter chips that sit between the i/o chip and the connector. As its a spare i've never got round to fixing it.

You can test the audio with a different line level audio source or amplifier - the mobo will plug into a hifi or any speaker with an aux unit. Similarly you can feed the amp a line level source, at least then you'll know whether its the mobo or amp. As you've already had suggested id be checking for dry joints on the audio amp rca's and the connections to its transformer.

If it turns out to be the amp I do have two spares but they're untested. I'd test them but i don't have the audio transformer. ( i dont have room for a naomi cab so mines hooked up to a vga monitor, pc speakers and a couple of joysticks.)

good luck!