[Repair Log] Sega Naomi

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    • bought another set of naomi2.

      by changing the components I now have to confirm the the mainboard is dead.

      filter board an net dim work with my new set.

      too bad.

      Thank you guys for all your help.

      And one more question about the voltage... it is now set up that the 5v line gives 5.0 without connection to the naomi2 and 4,85 when It is connected.i took the values at the jamma pins above the power connection at the filter board.

      is this ok? or too low?
    • hey guys,

      i measured the psu in the naomi cab iwill get to use my naomi 2 inside.

      the values were way to high.

      5,2 v
      3,60 v
      and 13,6 v

      all measured without load

      original sun psu.

      the 5 Volt line i was able to turn down a but Inder 5 v.

      the 3,3 line i was able to turn to 3,45

      but the 12v line i was not able to reduce the values.

      i am afraid that my new naomi will also be damaged again.

      any ideas what i can do?

      recap the psu?

      thanks
    • Those sun power supplies are a bit like pc atx supplies and need a minimum load.
      If you are scared to fry your naomi, you can connect something like a 12V halogene spot to keep it happy.

      A beefy resistor can work as well. Load the 5V and 3V3 with at least 300mA

      So that's 5V / 0.5 = 10 ohms minimum 3W resistor (5 or 10 W recommended as it will become hot)
      And 3V3 / 0.5 = 6.8 ohms minimum 2W resistor.

      The 12V usually doesn't has to be very accurate. It's often only used for fan's and audio amplifiers. (No need to load it either)

      Normally with such loads, you should be able to adjust 5V and 3V3 properly.

      This doesn't mean that recapping is a bad idea.
    • obcd wrote:

      Those sun power supplies are a bit like pc atx supplies and need a minimum load.
      If you are scared to fry your naomi, you can connect something like a 12V halogene spot to keep it happy.

      A beefy resistor can work as well. Load the 5V and 3V3 with at least 300mA

      So that's 5V / 0.5 = 10 ohms minimum 3W resistor (5 or 10 W recommended as it will become hot)
      And 3V3 / 0.5 = 6.8 ohms minimum 2W resistor.

      The 12V usually doesn't has to be very accurate. It's often only used for fan's and audio amplifiers. (No need to load it either)

      Normally with such loads, you should be able to adjust 5V and 3V3 properly.

      This doesn't mean that recapping is a bad idea.
      i think the 3,3 and 5 v are ok like this.

      if you say that the 12v line will not damage anything then it is ok. i was afraid of this one
    • Dumb question but what is the best way to test this under load? Just put the DMM leads on the ends of the connectors with the game powered up? (Prob sounds bad but I doubt it would cause any issues). I checked my voltages after my recap I did on the SUN PSU in my IDAS3 Single Cab and I think the 3.3 was more like 3.5 at no load and the 5v was like 5.15 (No load). Is that too high? It's been running stable for quite a while so I figure it is fine I just figured it would be worth checking :)
    • If the game is connected, wouldn't that mean the supply is having some load?
      5.1V - 5.15V should be fine, but 3.5 is a bit high.
      Try to lower it to 3.35. Measure it on the connector that's plugged in the naomi.
      Measuring it there means you already compensate the cable losses in the wires going from the supply to the naomi.
    • obcd wrote:

      If the game is connected, wouldn't that mean the supply is having some load?
      5.1V - 5.15V should be fine, but 3.5 is a bit high.
      Try to lower it to 3.35. Measure it on the connector that's plugged in the naomi.
      Measuring it there means you already compensate the cable losses in the wires going from the supply to the naomi.
      This is good advice. Yeah I should have been clearer, the testing I did was when i put the psu back into the game and reconnected it to power then before plugging it into the Naomi I checked voltage at the connectors. I'll measure the psu underload at the connectors on the Naomi. This is a good idea.