1 - Supercaps and NETDIMMs

Author: sgeorge, Posted on: 9 January 2017 14:43

So, apparently the supercap on the NAOMI motherboard can start leaking and corrode the traces, so its good to replace it or just remove it entirely. A lot of people seem to replace like with like, except these caps have been discontinued by Panasonic a long time ago, so they replace an leaky old cap with an old cap... The logic there to me is very broken.

Now this is a basic 0.1F, 5.5v supercap. You can get lots of these, but the problem lies in the change in the lead spacing.

The original cap is a Panasonic EECS0HD104H with 10mm lead spacing. Most of similar sized supercaps today have a 5mm lead spacing.

(The supercap is the small 1cm wide cap between the CR2032 battery and the 6 pin eeprom).

There does seem to be an agreement that it works perfectly fine without the supercap, so I think I'm going to remove mine from the board without replacing it.

Here is a quick way to test the CR2032 battery on your NAOMI. I'm using the via on the ground plane next to the '-' on the battery, and the top of the battery ('+'), this is showing us 3v so were still good.

I am surprised the battery is connected to the ground plane, but it is.

While we have everything out, might be good to take a look at the NET DIMM board, check its memory and configuration.

You can see we only have 1 stick of ram (Its 168 pin PC133 CL3 SDRAM, 3.3v). We are going to replace this with 2 x 256mb PC133 CL3 sticks of ram,

aaaand look, those jumpers near the SCSI connector need to be changed.

(Mmmm Spreadsheets, so good for rudimentary drawings!) image

Right now you can see the board setup for GDROM boot on the SCSI connector;

But we've changed it to boot over the network!

tags: NAOMI, NetDIMM, SEGA, SuperCap


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