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128MB SDRAM v3.0 unstable

Posted: Thu Oct 24, 2024 8:14 am
by Robertkopp

Hello I got a prebuilt qmtech kit without the integrated SDRAM.

It becomes somewhat unstable on lower frequencies (GBA and PSX do not work at all), but for example I can play the Cave and Raizing Arcade shmups from start to finish.

I pulled the RAM to investigate. GBA works without, so the de10 should be ok.
The RAM was missing the l1117f voltage regulator, so I got one and put it onto the board. No apperent changes yet.

I would try changing the capacitors next, but I only got the 1uf and the .1uf. 10uf was sold out everywhere I looked.
I only have some out of a Chinese capacitor sample book, but those are only rated for 10v.

A 10v rating should be just enough right?


Re: 128MB SDRAM v3.0 unstable

Posted: Thu Oct 24, 2024 2:41 pm
by Xbytez

Capacitors will not make a huge difference if your having hard crashes in cores, run the memtest core on each individual chip on the SDRAM board, my guess is one will be faulty.

10V rated capacitors will be fine.


Re: 128MB SDRAM v3.0 unstable

Posted: Fri Oct 25, 2024 1:02 am
by Robertkopp

Thx and yes you where correct. One chip is toast. Cheers mate.