What's wrong with my Naomi 2?

PCB problems and fixes
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dj_johnnyg
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What's wrong with my Naomi 2?

Post by dj_johnnyg » September 22nd, 2019, 6:23 am

After some help with a weird issue on my Naomi 2.

Current setup is N2, netbooting with a multi-BIOS, in a mushiking cab with Sanwa 15k monitor.

Everything has been working fine for a good 12 months or so, but not been used over the winter.
Turned the unit on today, as part of the never ending arcade project, and noticed something odd with the picture.

The image is displaying fine, but the screen is almost pulsating, almost like the refresh rate is not correct. Fired up Gigawing 2 and noticed that during the demo/attract mode the issue stops when it transitions to a new part (so basically static images look fine, but as soon as there's motion, the "flashing" starts again.

Any ideas?

Tried my Naomi 1, which isn't showing the issue (but is giving me an Error 34 Gateway issue :-x ), and also tried **** about with the monitor adjustments, but no joy.

It's not the 15/31k dip, as when in 31k mode I get 2 squashed images (and still the same flashing) - could it be the multi-BIOS? I'll have to work out where I decided to put my N2 BIOS for safe-keeping :awe: in order to be sure.

I'm not 100% bothered if the N2 is **** (as long as I can get the N1 netbooting), since I'm only missing out on VS3, VF4 and beachspikers, but like to have a spare system, and I can't source Naomi stuff here easily (or more importantly cheaply)

Thanks

John
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nem
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Re: What's wrong with my Naomi 2?

Post by nem » September 22nd, 2019, 12:28 pm

Sounds to me like a monitor issue more than a game board one.

Do you notice the pulsing also in the boot-up screen when the Naomi logo comes up?

Gateway error points to incorrect settings in the network configurations. Copy those from the Naomi 2 to your Naomi 1.

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dj_johnnyg
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Re: What's wrong with my Naomi 2?

Post by dj_johnnyg » September 23rd, 2019, 5:17 am

Naomi 1 is fixed - I forgot you have to power-off for the network settings to actually work, the reboot doesn't seem to work for me :awe:

Anyway, I think the N2 is toast.

I've found the original Export BIOS, and swapped it out, but still the same issues. I've tried in the other cab, and again the same. Changed the filter-board, and run with no cart/DIMM since the issue manifests on bootup anyway.
Naomi 1 and JAMMA boards (via riverservice adapter) playing nicely too.

It seems to be worse today. When doing the Naomi bootup, the screen looks to be split into 6 columns, with the 1st, 3rd and 5th rendering fine, but the 2nd, 4th and 6th basically being screwed.
I could be talking **** here, but do the 2 PowerVR chips render sections of the screen each? I decased the motherboard, and when pushing on the fan over the PowerVR nearest the filterboard the ****-rendered bars got worse.

Any ideas, other than e-waste recycling? Can I use a hot-gun over the suspect chip, or is it likely to need a costly reballing? If it's duff, anything worth salvaging off the board?

Anyone in the UK or NZ got a cheap Naomi mobo for sale? :awe:
Snakes: They're like bits of rope, only angrier.

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dj_johnnyg
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Re: What's wrong with my Naomi 2?

Post by dj_johnnyg » September 23rd, 2019, 5:40 am

Just done a RAM test, and it looks like IC22 & 23 are bad.

Anyone know a good source & part number for the RAM?

Cheers
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nem
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Re: What's wrong with my Naomi 2?

Post by nem » September 23rd, 2019, 10:15 am

The part number for the RAM is on top of the chip. I looked into it sometime back and I couldn't find them anywhere else except Alibaba.

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Re: What's wrong with my Naomi 2?

Post by whitecomet » September 24th, 2019, 11:56 am

It seems to be worse today. When doing the Naomi bootup, the screen looks to be split into 6 columns, with the 1st, 3rd and 5th rendering fine, but the 2nd, 4th and 6th basically being screwed.
Sounds like the GPU error I had...

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Re: What's wrong with my Naomi 2?

Post by Awbacon » September 27th, 2019, 3:53 pm

Its always weird when chips eat their own lunch when just sitting around doing nothing. Like how does an IC go bad doing nothing? Drives me nuts lol

Glad you diagnosed the problem!

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Re: What's wrong with my Naomi 2?

Post by dj_johnnyg » September 29th, 2019, 12:29 am

Sadly it is terminal.
Fired it up again to check no other RAM was fried, and totally dead. So into the spares bin it goes incase the N1 goes titsup.
Snakes: They're like bits of rope, only angrier.

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