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Naomi 2 netboot issue, failure at first reset

My gut says recap the PSU. Your crashes are similar to when I foolishly tried to power a netdimm from a capcom IO. The voltage measurement looks Ok but the system crashed under load.

Obviously you can't power a netdimm with a capcom IO, but the point is if you're short on amps, whether it be due to spec or age, a volt reading can still look fine.
 
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Guessing this is a lot? Just took it from the 3.3v without any load to isolate just the psu. Maybe re-capping time!
 
Scale on that is in the bottom corner 200mv. I ran it on other psu seems around 100mv on the 5v rail so maybe recap!
 
ekorz said:
Scale on that is in the bottom corner 200mv. I ran it on other psu seems around 100mv on the 5v rail so maybe recap!
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200mv is supposed to be the maximum allowable output voltage ripple peek to peek, so if that's actually 200mv wide, that's really bad. Time for a recap indeed.
 
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For science (and Ikaruga) I put the Naomi2 on my tate blast, whose psu I have recapped. Ripple image above looks much better, same settings, and the Naomi behaves at normal voltage.

Looks like I’ll be rebuilding this Lindbergh psu! I’ll save and publish a cap list. Thanks @mathieulh!

edit: maybe I spoke too soon hm. Will recap anyway but I’m getting intermittent results with my blast psu now at 3.3 on the connector :P
 
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Recapped it. Not much difference visually in the scope or functionally with the naomi2 so either a) something else is wrong, b) my method of measuring is suspect, or c) both and/or other!

I do get the same behavior on my one recapped blast psu. Might try the other one. I’m still interested in measuring the voltage drop as that still seems like a viable reason, and generally open to suggestions. At least bumping 3.3 to 3.4 on the connector seems to make it more reliable.
 
one thing I noticed that was weird this last weekend, was if I have the jamma harness and jvs power outside of the cab while testing i had power issues, but as soon as I put everything back inside the cab the intermittent power issues dissappear. almost as if the cables being extended outside caused a problem but being retracted inside eliminated the problem. Makes no sense as they length of the cable doesn't change, but it is a weird issue I noticed. I'm power a netdimm naomi through a blast psu.
 
Anselmo said:
Makes no sense as they length of the cable doesn't change, but it is a weird issue I noticed.
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it could be a bad wire that is internally broken so it's position changes how good the connection is. I run into this problem on 3d printers every so often where there's lots of repetitive movement it cold-works the wires (like bending a paperclip too many times back and forth)

alternatively this could be a dirty or loose connector that is getting more or less pressure depending on position. pretty common on edge connectors and poorly design connectors like molex, but not super common on positive-lock/double wipe stuff like a lot of the TE connectors you find in arcade machines.
 
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